Category Archives: Quantum Physics

By Emily Dieckman, College of Engineering

Thursday

Zheshen Zhang, a University of Arizona assistant professor ofmaterials science and engineering, is leading a $5 million quantum technology project to advance navigation for autonomous vehicles and spacecraft, as well as measurement of otherworldly materials such as dark matter and gravitational waves.

The National Science Foundation'sConvergence Accelerator Program, which fast-tracks multidisciplinary efforts to solve real-world problems, is funding the Quantum Sensors project.

In September 2020, 29 U.S. teams received phase I funding to develop solutions in either quantum technology or artificial intelligence-driven data sharing and modeling. Ten prototypes have advanced to phase II, each receiving $5 million, including two projects led by UArizona researchers Zhang's project and another by hydrology and atmospheric sciences assistant professor Laura Condon.

"Quantum technology and AI innovation are a priority for the National Science Foundation," said Douglas Maughan, head of the NSF Convergence Accelerator program. "Today's scientific priorities and national-scale societal challenges cannot be solved by a single discipline. Instead, the merging of new ideas, techniques and approaches, plus the Convergence Accelerator's innovation curriculum, enables teams to speed their research into application. We are excited to welcome Quantum Sensors into phase II and to assist them in applying our program fundamentals to ensure their solution provides a positive impact on society at large."

Upgrading Gyroscopes and Accelerometers

The objects we interact with in our daily lives adhere to classic laws of physics, like gravity and thermodynamics. Quantum physics, however, has different rules, and objects in quantum states can exhibit strange but useful properties. For example, when two particles are linked by quantum entanglement, anything that happens to one particle affects the other, no matter how far apart they are. This means probes in two locations can share information, allowing for more precise measurements. Or, while "classical" light emits photons at random intervals, scientists can induce a quantum state called "squeezed" light to make photon emission more regular and reduce uncertainty or "noise" in measurements.

The Quantum Sensors project will take advantage of quantum states to create ultrasensitive gyroscopes, accelerometers and other sensors. Gyroscopes are used in navigation of aircraft and other vehicles to maintain balance as orientation shifts. In tandem, accelerometers measure vibration or acceleration of motion. These navigation-grade gyroscopes and accelerometers are light-based and can be extremely precise, but they are bulky and expensive.

Many electronics, including cellphones, are equipped with tiny gyroscopes and accelerometers that enable features like automatic screen rotation and directional pointers for GPS apps. At this scale, gyroscopes are made up of micromechanical parts, rather than lasers or other light sources, rendering them far less precise. Zhang and his team aim to develop chip-scale light-based gyroscopes and accelerometers to outperform current mechanical methods. However, the detection of light at this scale is limited by the laws of quantum physics, presenting a fundamental performance limit for such optical gyroscopes and accelerometers.

Rather than combat these quantum limitations with classical resources, Zhang and his team are fighting fire with fire, so to speak, by using quantum resources. For example, the stability of squeezed light can counterbalance the uncertainty of quantum fluctuations, which are temporary changes in variables such as position and momentum.

"The fundamental quantum limit is induced by quantum fluctuations, but this limit can be broken using a quantum state of light, like entangled photons or squeezed light, for the laser itself," said Zhang, director of the university's Quantum Information and Materials Group. "With this method, we can arrive at much better measurements."

Gaining an Edge on Earth and Beyond

The benefits of extremely precise measurements are numerous. If a self-driving car could determine its exact location and speed using only a compact, quantum-enhanced, onboard gyroscope and accelerometer, it wouldn't need to rely on GPS to navigate. A self-contained navigation system would protect the car from hackers and provide more stability. The same goes for navigation of spacecraft and terrestrial vehicles sent to other planets.

"In both space-based and terrestrial technologies, there are a lot of fluctuations. In an urban environment, you might lose GPS signal driving through a tunnel," Zhang said. "This method could capture information not provided by a GPS. GPS tells you where you are, but it doesnt tell you your altitude, the direction your vehicle is driving or the angle of the road. With all of this information, the safety of the passengers would be ensured."

Zhang is collaborating with partners at General Dynamics Mission Systems, Honeywell, the NASA Jet Propulsion Laboratory, the National institute of Standards and Technology, Purdue University, Texas A&M University, UCLA and Morgan State University.

"We are excited to work with the University of Arizona on this NSF Convergence Accelerator project," said Jianfeng Wu, Honeywell representative and project co-principal investigator. "The integrated entangled light sources can reduce the noise floor and enable the navigation-grade performance from chip-scale gyroscopes. The success of this program will significantly disrupt the current gyroscope landscape from many perspectives."

Because precise navigation would directly affect 700 million people worldwide, researchers estimate that quantum sensors could create a $2.5 billion market by 2035. They also expect that the precision and stability offered by the technology will give researchers a way to measure previously unmeasurable forces, such as gravitational waves and dark matter.

"As a leading international research university bringing the Fourth Industrial Revolution to life, we are deeply committed to advance amazing new information technologies like quantum networking to benefit humankind, said University of Arizona PresidentRobert C. Robbins. "The University of Arizona is an internationally recognized leader in this area, and I look forward to seeing how Dr. Zhang's Quantum Sensors project moves us forward in addressing real-world challenges with quantum technology."

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UArizona Engineer Awarded $5M to Build Quantum-Powered Navigation Tools - The University of Arizona Research

Vedika Khemani, assistant professor of physics at Stanford University, has been awarded a New Horizons in Physics Prize from the Breakthrough Prize Foundation. Khemani was recognized for pioneering theoretical work formulating novel phases ofnon-equilibrium quantum matter, including time crystals.

Vedika Khemani (Image credit: Rod Searcey)

Time crystals got their name for the fact that, like crystals, they are structurally arranged in a repeating pattern. But, while standard crystals like diamonds or salt have an arrangement that repeats in space, time crystals repeat across time forever. Importantly, they do so without any input of energy, like a clock that runs forever without batteries. Khemanis work offered a theoretical formulation for the first time crystals, as well as a blueprint for their experimental creation. But she emphasizes that time crystals are only one of the exciting potential outcomes of out-of-equilibrium quantum physics, which is still a nascent field.

None of the world is in equilibrium; just look out your window, right? Were starting to see into these vastly larger spaces of how quantum systems evolve through experiments, said Khemani, who is faculty in the School of Humanities and Sciencesand a member of Q-Farm, Stanfords broad interdisciplinary initiative in quantum science and engineering. Im very excited to see what kinds of new physics these new regimes will bring. Time crystals are one example of something new we could get, but I think its just the beginning.

The $100,000 New Horizons Prize in Physics is given each year to up to three promising junior researchers who have already produced important work, according to the prize website. New Horizons prizes are one of three groups of Breakthrough Prizes in physics the others are the $3 million Special Breakthrough Prize and the $3 million Breakthrough Prize. The Breakthrough Prizes also recognize researchers in mathematics and life sciences. Called the Oscars of Science, the prizes are celebrated at a gala award ceremony presented by superstars of movies, music, sports and tech entrepreneurship. Since the prizes began in 2012, 10 Stanford faculty and researchers have won Breakthrough Prizes.

The concept of time crystals was first proposed in 2012 by physicist and Nobel laureate Frank Wilczek, but the idea was met with significant skepticism and comparisons to the impossible perpetual motion machine. In 2014, shortly after Wilczeks proposal, it was shown by Masaki Oshikawa and Haruki Watanabe that fundamental laws of thermodynamics provably forbid the existence of time crystals. (Watanabe is a co-recipient of the New Horizons Prize.)

Thus, Khemani wasnt thinking of time crystals at all as she went about her graduate work at Princeton University on non-equilibrium quantum physics. But in 2016, a reviewer for a preprint paper co-authored by Khemani pointed out that she and her colleagues had, without intending to, outlined a working model for time crystals.

I think if we had set out to find the time crystal we would have run into the same kinds of objections as Wilczek, said Khemani. Instead, we were thinking about: How do we generalize the ideas of quantum phases of matter to systems that are out of equilibrium?

Khemani and her doctoral advisor, Shivaji Sondhi, a professor of physics at Princeton University, were working on the problem of many-body localization. In a many-body localized system, particles get stuck in the state in which they started and can never relax to an equilibrium state. As such, these systems lie strictly outside the framework of equilibrium thermodynamics, which underpins our conventional understanding of all phases of matter.

Sondhi and Khemani worked with Achilleas Lazarides and Roderich Moessner at the Max Planck Institute to figure out how to think about phases of matter in many-body localized systems that are periodically driven in time, for instance by a laser. They found that, while equilibrium thermodynamics goes out the window, the possibility of formulating phases of matter need not. In addition to abstract theoretical formulations, they studied a concrete model: a periodically driven system of Ising spins. (The Ising model is often described as the fruit fly of statistical physics and has been extensively studied in equilibrium to understand fundamental phenomena, such as magnetism.)

These researchers found a number of phases in the out-of-equilibrium Ising model, including a novel one in which the system displays a stable, repetitive flip between patterns that repeat in time forever, at a period twice that of the driving period of the laser. (As required by the definition of time crystals, the laser does not impart energy into the system.) The phase Khemani and co-workers had found was, in fact, a time crystal the out-of-equilibrium setting in which they were working allowed them to evade the constraints imposed by the laws of thermodynamics.

In the months that followed the preprint, important properties about the new phase were worked out by Khemani and her collaborators, notably Curt von Keyserlingk at the University of Birmingham, as well as a by Dominic Else, Bela Bauer and Chetan Nayak at Microsoft Station Q. (Else and collaborators also independently identified Khemanis model as a time crystal, and Else is a co-recipient of the New Horizons Prize.) It was found that the phase displays a remarkable amount of robustness and stability. Then, various early experiments in 2017 showed promising precursors of the phase although they were ultimately found to not realize a stable many-body time crystal.

Khemani describes work in the years that followed as creating a checklist of what actually makes a time crystal a time crystal, and the measurements needed to experimentally establish its existence, both under ideal and realistic conditions.

In 2020, Matteo Ippoliti, a postdoctoral scholar at Stanford working with Khemani, and others published a proposal for experimentally realizing a time crystal using the unique capabilities of Googles Sycamore quantum computer. Following this proposal, this summer, Ippoliti and Khemani, collaborating with the large Google Quantum AI team, published a preprint paper detailing the experimental creation of the first-ever time crystal on Googles device. That paper is now undergoing peer review.

Khemani sees great promise in these types of quantum experiments for many-body physics.

While many of these efforts are broadly motivated by the quest to build quantum computers which may only be achievable in the distant future, if at all these devices are also, and immediately, useful when viewed as experimental platforms for probing new nonequilibrium regimes in many-body physics, said Khemani.

As for the award recognizing all of this work, Khemani described how it reflects the bigger picture. This is called the New Horizons prize and I do think we are looking at new horizons in physics, she said. There are people at Stanford who think about black holes and big astronomical questions talking to people who are trying to build quantum computers, talking to many-body theorists, talking to quantum information scientists. Its really exciting when you start getting so many different perspectives and so many different new ways of looking at problems.

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Vedika Khemani wins Breakthrough New Horizons Prize | Stanford News - Stanford University News

After leaving the European Organization for Nuclear Research (CERN) physics laboratory years ago, I crossed the Swiss-German border by high-speed train. Looking out the window of the carriage, I was enthralled by the scenes flashing by: a young couple embracing on an otherwise deserted platform, an old man standing by a rusty wagon with a missing wheel, two girls wading into a reedy pond. Each was just a few flickering frames, gone in the blink of an eye, but enough for my imagination to fill in a story.

I had just finished writing up some theoretical work on muon particlesheavier cousins to electronsand it was out for the scrutiny of my particle physics colleagues during peer review. There was a symmetry between my thoughts as I looked out the train window that day and the research I had been working on. I had been analyzing the flickering effects of unseen virtual particles on muons, aiming to use the clues from these interactions to piece together a fuller picture of our quantum universe. As a young theorist just launching my career, I had heard about proposed experiments to measure the tiny wobbles of muons to gather such clues. I had just spent my last few months at CERN working on an idea that could relate these wobbling muons to the identity of the missing dark matter that dominates our universe and other mysteries. My mind fast-forwarding, I thought, Greatnow I just have to wait for the experiments to sort things out. Little did I suspect that I would end up waiting for a quarter of a century.

Finally, this past April, I tuned in to a Webcast from my home institution, Fermi National Accelerator Laboratory (Fermilab) near Chicago, where scientists were reporting findings from the Muon g-2 (g minus two) experiment. Thousands of people around the world watched to see if the laws of physics would soon need to be rewritten. The Fermilab project was following up on a 2001 experiment that found tantalizing hints of the muon wobble effect I had been hoping for. That trial didnt produce enough data to be definitive. But now Muon g-2 co-spokesperson Chris Polly was unveiling the long-awaited results from the experiments first run. I watched with excitement as he showed a collection of new evidence that agreed with the earlier trial, both suggesting that muons are not acting as current theory prescribes. With the evidence from these two experiments, we are now very near the rigorous statistical threshold physicists require to claim a discovery.

What is this wobble effect that has me and other scientists so intrigued? It has to do with the way a muon spins when it travels through a magnetic field. This variation in spin direction can be affected by virtual particles that appear and disappear in empty space according to the weird rules of quantum mechanics. If there are additional particles in the universe beyond the ones we know about, they, too, will show up as virtual particles and exert an influence on a muons spin in our experiments. And this seems to be what we are seeing. The Fermilab experiment and its precursor measured a stronger wobble in muons spins than what we expect based on just the known particles. If the current discrepancy holds up, this will be the biggest breakthrough in particle physics since the discovery of the Higgs bosonthe most recent novel particle discovered. We might be observing the effects of particles that could help unveil the identity of dark matter or even reveal a new force of nature.

My romance with physics began when I was a child, gazing in amazement at the Via Lactea (the Milky Way) in the deep dark sky of Argentinas Pampas where I grew up. The same wonder fills me now. It is my job as a particle physicist to investigate what the universe is made of, how it works and how it began.

Scientists believe there is a simple yet elegant mathematical structure, based on symmetries of nature, that describes the way microscopic elementary particles interact with one another through the electromagnetic, weak and strong forces; this is the miracle of particle physics that scientists prosaically call the Standard Model. The distant stars are made of the same three elementary matter particles as our bodies: the electron and the up and down quarks, the two latter of which form protons and neutrons. Starlight is the result of the electromagnetic force acting between the charged protons and electrons, liberating light energy at the hot surface of the star. The heat source of these stars, including our sun, is the strong force, which acts on the protons and neutrons to produce nuclear fusion. And the weak force, which operates on both the quarks and the electrons, turns protons into neutrons and positively charged electrons and controls the rate of the first step in the fusion process. (The fourth force of nature, gravity, is not part of the Standard Model, although integrating it with the other forces is a major goal.)

Physicists assembled the Standard Model piece by piece over the course of decades. At particle accelerators around the world, we have been able to create and observe all of the particles that the mathematical structure requires. The last to be found, the Higgs boson, was discovered almost a decade ago at CERNs Large Hadron Collider (LHC). Yet we know the Standard Model is not complete. It does not explain, for example, the 85 percent of the matter in the universedark matterthat holds the cosmos together, making galaxies such as our Milky Way possible. The Standard Model falls short of answering why, at some early time in our universes history, matter prevailed over antimatter, enabling our existence. And the Muon g-2 experiment at Fermilab may now be showing that the Standard Model, as splendid as it is, describes just a part of a richer subatomic world.

The subject of the experimentmuonsare produced in abundance by cosmic rays in Earths atmosphere; more than 10,000 of them pass through our bodies every minute. These particles have the same physical properties as the familiar electron, but they are 200 times heavier. The extra mass makes them better probes for new phenomena in high-precision laboratories because any deviations from their expected behavior will be more noticeable. At Fermilab, a 50-foot-diameter ring of powerful magnets stores muons created under controlled conditions by smashing a beam of protons from a particle accelerator into a target of mostly nickel. This process produces pions, unstable composite particles that then decay into neutrinos and muons through weak force effects. At this point, the muons enter a ring filled with the vacuum of empty space.

Like electrons, muons have electric charge and a property we call spin, which makes them behave as little magnets. Because of the way they were created, when negatively charged muons enter the ring their spins point in the same direction as their motion, whereas for positively charged muons (used in the Fermilab experiment) the spins point in the opposite direction of their motion. An external magnetic field makes the electrically charged muons orbit around the ring at almost the speed of light. At the same time, this magnetic field causes the spin of the muons to precess smoothly like a gyroscope, as the particles travel around the ring, but with a small wobble.

The rate of precession depends on the strength of the muons internal magnet and is proportional to a factor that we call g. The way the equations of the Standard Model are written, if the muon didnt wobble at all, the value of g would be 2. If that were the case, the muons direction of motion and direction of spin would always be the same with respect to each other, and g-2 would be zero. In that case, scientists would measure no wobble of the muon. This situation is exactly what we would expect without considering the properties of the vacuum.

But quantum physics tells us that the nothingness of empty space is the most mysterious substance in the universe. This is because empty space contains virtual particlesshort-lived objects whose physical effects are very real. All the Standard Model particles we know of can behave as virtual particles as a result of the uncertainty principle, an element of quantum theory that limits the precision with which we can perform measurements. As a result, it is possible that for a very short time the uncertainty in the energy of a particle can be so large that a particle can spring into existence from empty space. This mind-blowing feature of the quantum world plays a crucial role in particle physics experiments; indeed, the discovery of the Higgs boson was enabled by virtual particle effects at the LHC.

Virtual particles also interact with the muons in the Fermilab ring and change the value of g. You can imagine the virtual particles as ephemeral companions that a muon emits and immediately reabsorbsthey follow it around like a little cloud, changing its magnetic properties and thus its spin precession. Therefore, scientists always knew that g would not be exactly 2 and that there would be some wobble as muons spin around the ring. But if the Standard Model is not the whole story, then other particles that we have not yet discovered may also be found in that cloud, changing the value of g in ways that the Standard Model cannot predict.

Muons themselves are unstable particles, but they live long enough inside the Muon g-2 experiment for physicists to measure their spin direction. Physicists do this by monitoring one of the decay particles they create: electrons, from decays of negatively charged muons, or positronsthe antiparticle version of electronsfrom decays of positively charged muons. By determining the energy and arrival time of the electrons or positrons, scientists can deduce the spin direction of the parent muon. A team of about 200 physicists from 35 universities and labs in seven countries developed techniques for measuring the muon g-2 property with unprecedented accuracy.

The first experiments to measure the muon g-2 took place at CERN, and by the late 1970s they had produced results that, within their impressive but limited precision, agreed with standard theory. In the late 1990s the E821 Muon g-2 experiment at Brookhaven National Laboratory started taking data, with a similar setup to that at CERN. It ran until 2001 and got impressive results showing an intriguing discrepancy from the Standard Model calculations. It collected only enough data to establish a three-sigma deviation from the Standard Modelwell short of the five-sigma statistical significance physicists require for a discovery.

A decade later Fermilab acquired the original Brookhaven muon ring, shipped the 50-ton apparatus from Long Island to Chicago via highways, rivers and an ocean, and started the next generation of the Muon g-2 experiment. Nearly a decade after that, Fermilab announced a measurement of muon wobble with an uncertainty of less than half a part in a million. This impressive accuracy, achieved with just the first 6 percent of the expected data from the experiment, is comparable to the result from the full run of the Brookhaven trial. Most important, the new Fermilab results are in striking agreement with the E821 values, confirming that the Brookhaven findings were not a fluke.

To confirm this years results, we need not just more experimental data but also a better understanding of what exactly our theories predict. Over the past two decades we have been refining the Standard Model predictions. Most recently, more than 100 physicists working on the Muon g-2 Theory Initiative, started by Aida El-Khadra of the University of Illinois, have strived to improve the accuracy of the Standard Models value for the muon g-2 factor. Advances in mathematical methods and com putational power have enabled the most accurate theoretical calculation of g yet, taking into account the effects from all virtual Standard Model particles that interact with muons through the electromagnetic, weak and strong forces. Just months before Fermilab revealed its latest experimental measurements, the theory initiative unveiled their new calculation. The number disagrees with the experimental result by 4.2 sigma, which means that the chances that the discrepancy is purely a statistical fluctuation are about one in 40,000.

Still, the latest theoretical calculation is not iron-clad. The contributions to the g-2 factor governed by effects from the strong force are extremely difficult to compute. The Muon g-2 Theory Initiative used input from two decades of judiciously measured data in related experiments with electrons to evaluate these effects. Another technique, though, is to try to calculate the size of the effects directly from theoretical principles. This calculation is way too complex to solve exactly, but physicists can make approximations using a mathematical trick that discretizes our world into a gridlike lattice of space and time. These techniques have yielded highly accurate results for other computations where strong forces play a dominant role.

Teams around the world are tackling the lattice calculations for the muon g-2 factor. So far only one team has claimed to have a result of comparable accuracy to those based on experimental data from electron collisions. This result happens to dilute the discrepancy between the experimental and Standard Model expectationsif it is correct, there may not be evidence of additional particles tugging on the muon after all. Yet this lattice result, if confirmed by other groups, would itself conflict with experimental electron datathe puzzle then would be our understanding of electron collisions. And it would be hard to find theoretical effects that would explain such a result because electron collisions have been so thoroughly studied.

If the mismatch between Fermilabs measurements and theory persists, we may be glimpsing an uncharted world of unfamiliar forces, novel symmetries of nature and new particles. In the research I published 25 years ago searching for clues about the muons wobble, my collaborators and I considered a proposed property of nature called supersymmetry. This idea bridges two categories of particlesbosons, which can be packed together in large numbers, and fermions, which are antisocial and will share space only with particles of opposite spin. Supersymmetry postulates that each fermion matter particle of the Standard Model has a yet to be discovered boson particle superpartner, and each Standard Model boson particle also has an undiscovered fermion superpartner. Supersymmetry promises to unify the three Standard Model forces and offers natural explanations for dark matter and the victory of matter over antimatter. It may also explain the striking Muon g-2 results.

Just after the Fermilab collaboration announced its measurement, my colleagues Sebastian Baum, Nausheen Shah, Carlos Wagner and I posted a paper to a preprint server investigating this intriguing notion. Our calculations showed that virtual superparticles in the vacuum could make the muons wobble faster than the Standard Model predicts, just as the experiment saw. Even more exhilarating, one of those new particlescalled a neutralinois a candidate for dark matter. Supersymmetry can take numerous forms, many of them already ruled out by data from the LHC and other experimentsbut plenty of versions are still viable theories of nature.

The paper my team submitted was just one of more than 100 that have appeared proposing possible explanations for the Muon g-2 result since it was announced. Most of these papers suggest new particles that fall into one of two camps: either light and feeble or heavy and strong. The first category includes new particles that have masses comparable to or smaller than the muon and that interact with muons with a strength millions of times weaker than the electromagnetic force. The simplest theoretical models of this type involve new, lighter cousins of the Higgs boson or particles related to new forces of nature that act on muons. These new light particles and feeble forces could be hard to detect in terrestrial experiments other than Muon g-2, but they may have left clues in the cosmos. These light particles would have been produced in huge numbers after the big bang and might have had a measurable effect on cosmic expansion. The same ideathat light particles and feeble forces wrote a chapter missing from our current history of the universehas also been proposed to explain discrepancies in observations of the expansion rate of space, the so-called Hubble constant crisis.

The second category of explanations for the muon resultsheavy and stronginvolves particles with masses about as heavy as the Higgs boson (roughly 125 times the mass of a proton) to up to 100 times heavier. These particles could interact with muons with a strength comparable to the electromagnetic and weak interactions. Such heavy particles might be cousins of the Higgs boson, or exotic matter particles, or they might be carriers of a new force of nature that works over a short range. Supersymmetry offers some models of this type, so my youthful speculations at CERN are still in the running. Another possibility is a new type of particle called a leptoquarka strange kind of boson that shares properties with quarks as well as leptons such as the muon. Depending on how heavy the new particles are and the strength of their interactions with Standard Model particles, they might be detectable in upcoming runs of the LHC.

Some recent LHC data already point toward unusual behavior involving muons. Recently, for instance, LHCb (one of the experiments at the LHC) measured the decays of certain unstable composite particles similar to pions that produce either muons or electrons. If muons are just heavier cousins of the electron, as the Standard Model claims, then we can precisely predict what fraction of these decays should produce muons versus electrons. But LHCb data show a persistent three-sigma discrepancy from this prediction, perhaps indicating that muons are more different from electrons than the Standard Model allows. It is reasonable to wonder whether the results from LHCb and Muon g-2 are different, flickering frames of the same story.

The Muon g-2 experiment may be telling us something new, with implications far beyond the muons themselves. Theorists can engineer scenarios where new particles and forces explain both the muons funny wobbling and solve other outstanding mysteries, such as the nature of dark matter or, even more daring, why matter dominates over antimatter. The Fermilab experiment has given us a first glimpse of what is going on, but I expect it will take many more experiments, both ongoing and yet to be conceived, before we can confidently finish the story. If supersymmetry is part of the answer, we have a fair chance of observing some of the superparticles at the LHC. We hope to see evidence of dark matter particles there or in deep underground labs seeking them. We can also look at the behavior of muons in different kinds of experiments, such as LHCb.

All of these experiments will keep running. Muon g-2 should eventually produce results with nearly 20 times more data. I suspect, however, that the final measured value of the g-2 factor will not significantly change. There is still a shadow of doubt on the theory side that will be clarified in the next few years, as lattice computations using the worlds most powerful supercomputers achieve higher precision and as independent teams converge on a final verdict for the Standard Model prediction of the g-2 factor. If a big mismatch between the prediction and the measurement persists, it will shake the foundations of physics.

Muons have always been full of surprises. Their very existence prompted physicist I. I. Rabi to complain, Who ordered that? when they were first discovered in 1936. Nearly a century later they are still amazing us. Now it seems muons may be the messengers of a new order in the cosmos and, for me personally, a dream come true.

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Weird Muons May Point to New Particles and Forces of Nature - Scientific American

Physicists have created the first-ever atomic vortex beam a swirling tornado ofatomsand molecules with mysterious properties that have yet to be understood.

By sending a straight beam of helium atoms through a grating with teeny slits, scientists were able to use the weird rules of quantum mechanics to transform the beam into a whirling vortex.

The extra gusto provided by the beam's rotation, called orbital angular momentum, gives it a new direction to move in, enabling it to act in ways that researchers have yet to predict.

For instance, they believe the atoms' rotation could add extra dimensions ofmagnetismto the beam, alongside other unpredictable effects, due to the electrons and the nuclei inside the spiraling vortex atoms spinning at different speeds.

Related:The 18 biggest unsolved mysteries in physics

"One possibility is that this could also change the magnetic moment of the atom," or the intrinsic magnetism of a particle that makes it act like a tiny bar magnet, study co-author Yair Segev, a physicist at the University of California, Berkeley, told Live Science.

In the simplified, classical picture of the atom, negatively-charged electrons orbit a positively-charged atomic nucleus. In this view, Segev said that as the atoms spin as a whole, the electrons inside the vortex would rotate at a faster speed than the nuclei, "creating different opposing [electrical] currents" as they twist.

This could, according to the famouslaw of magnetic inductionoutlined by Michael Faraday, produce all kinds of new magnetic effects, such as magnetic moments that point through the center of the beam and out of the atoms themselves, alongside more effects that they cannot predict.

The researchers created the beam by sendingheliumatoms through a grid of tiny slits each just 600 nanometers across.

In the realm ofquantum mechanics the set of rules which govern the world of the very small atoms can behave both like particles and tiny waves; as such, the beam of wave-like helium atoms diffracted through the grid, bending so much that they emerged as a vortex that corkscrewed its way through space.

The whirling atoms then arrived at a detector, which showed multiple beams diffracted to differing extents to have varying angular momentums as tiny little doughnut-like rings imprinted across it.

The scientists also spotted even smaller, brighter doughnut rings wedged inside the central three swirls. These are the telltale signs of helium excimers a molecule formed when one energetically excited helium atom sticks to another helium atom. (Normally, helium is a noble gas and doesn't bind with anything.)

The orbital angular momentum given to atoms inside the spiraling beam also changes the quantum mechanical "selection rules" that determine how the swirling atoms will interact with other particles, Segev said. Next, the researchers will smash their helium beams into photons, electrons, and atoms of elements besides helium to see how they might behave.

If their rotating beam does indeed act differently, it could become an ideal candidate for a new type of microscope that can peer into undiscovered details on the subatomic level. The beam could, according to Segev, give us more information on some surfaces by changing the image that is imprinted upon the beam atoms bounced off it.

"I think that as is often the case in science, it's not a leap of capability that leads to something new, but rather a change in perspective," Segev said.

The researchers published their findings September 3 in the journalScience.

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The 11 biggest unanswered questions about dark matter

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18 times quantum particles blew our minds

This article was originally published by Live Science. Read the original article here.

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Physicists Create Swirling Tornado of Helium With First-Ever Atomic Vortex Beam - ScienceAlert

Thanu Padmanabhan had acquired outstanding mathematical abilities quite early in his life, thanks to the guidance of his father who was an extremely gifted mathematician but was forced to take up a job with the Forest Department in Kerala.

An academic career in pure mathematics was what Padmanabhan had decided to pursue. But that was before he had picked up Richard Feynmans classic Lectures in Physics, the book that has lured countless youngsters like him from several generations to physics. In a profile included in the book Gravity and the Quantum, a collection of Padmanabhans articles released on the occasion of his 60th birthday, his PhD students Jasjit Bagla and Sunu Engineer wrote that Feynmans book had a big influence on him even though he was not a big fan of the celebrated scientist as a person. It appeared to me that theoretical physics beautifully combines the best of objective science and the elegance of pure mathematics, Padmanabhan, who died in Pune on Friday, aged 64, is quoted in that profile as saying.

Padmanabhan, or Paddy as he was known to his colleagues and students, went on to achieve great heights in theoretical physics, making important contributions to the fields of gravity and quantum theory, structure and formation of universe.

His early work was done at Mumbais Tata Institute of Fundamental Research, where he did his PhD under Jayant Narlikar,starting an association that lasted a lifetime. Padmanabhan shifted to the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in Pune in 1992 and remained there till his death, researching, teaching, and popularising science.

As a teacher, he could explain any topic or subject to a student with great ease. He taught me that discipline and hard work, when coupled, would ensure that one keeps growing, said Dr Tirthankar Roy Choudhury, Padmanabhans PhD student between 1999 and 2003 at IUCAA.

His demise came as a shock to the scientific community, especially those at IUCAA. A lot of them turned up to pay their lastrespects on Friday afternoon. He was later cremated at Aundh.

Padmanabhan could teach any course in Physics and Astronomy with equal ease, said Dr Yogesh Wadedekar, senior scientist at National Centre for Radio Astrophysics (NCRA),Pune.

Padmanabhan loved solving puzzles, playing chess and watching movies across genres.

There was a phase when he used to watch a lot of movies on TV. Some of us students used to pull his leg about his liking for the actress Tabu. He used to throw a party for us whenever he won an award or a recognition which were numerous.

Whenever we used to go out for dinners, he would order tiramisu for dessert and we used to again make fun of this habit, shared A N Ramaprakash, scientist and colleague at IUCAA.

He would often play games of chess on the computer. He was a sharp thinker and would be the problem spotter, recalled Sanjit Mitra, another colleague at IUCAA.

Many never get a chance to meet their idols in life but Tirthankar Roy Choudhury got to not only work closely but remain associated with his idol for nearly 20 years. When I was chosen under his guide-ship for PhD, it was like a dream cometrue. He would never stop or be tired and would often take up new and the most difficult problems, recalled Choudhury.

Padmanabhan was an outstanding scientist who could catch a scientific argument quickly while at the same time admit if he did not possess knowledge about the topic, said Prof Yashwant Gupta, centre director, NCRA.

Through his work over the past decade or so, Padmanabhan had discovered a deep connection between the underlying quantum nature of the structure of space-time and what we perceive as the macro properties of gravity, Ramaprakash stated. This is seminal and path-breaking. He was just warming up to understanding the consequences of this discovery, but had to go, he said.

Mitra particularly remnisences the extended conversations he had with Padmanabhan, when the two would cross paths during their respective evening walks.

We would get talking on any topic and would often end up having interesting discussions lasting even upto 45 minutes during the evening walks, he said.

While pursuing science was a daily affair, Padmanabhan also took to writing books both on advanced and popular science in the early 1990s, and soon realised the need of a personal computer at his home.

Roy Choudhury remembers Padmanabhans witty nature and said that some people would fail to understand the light humour. When assigned teaching responsibility many years ago, Padmanabhan guided Roy Choudhury from time-to-time.

Padmanabhans comic strip called The Story of Physics was both popular and loved by students, shared Dr Raka Dabhade, head, Department of Physics, Fergusson College. His humble nature always attracted students to interact with him. In spite of his busy schedule, he would find time to clear doubts of the students via emails, said Dabhade.

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The professor who loved puzzles, and had his own comic strip on physics - The Indian Express

There are some inventions that do not have a major impact on our daily lives until much later. Like the invention that you could use to store information on a disc with pits and bumps and read it with a laser. Thats when the CD was born. Last month, Austrian scientists managed to make quantum matter (read the IO article here) that can be both a liquid and a solid. The practical application is still some time away. But it could have a major impact on the development of new materials.

The Innsbruck research team managed to form a crystal and a superfluid at the same time. Superfluids are liquids that flow without any resistance. The experiment was based on magnetic atoms and an ultracold quantum gas, called the Bose Einstein condensate. This is what is created when a gas is cooled to just above absolute zero (minus 273 degrees Celsius).

Also interesting: Relationship discovered between quantum physics and spacetime

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In everyday life, we can only observe three states of aggregation: gaseous, liquid and solid. Substances change their state of aggregation, for example, by changing temperature. Usually substances are solid at low temperatures and gaseous at high temperatures. But if you take a highly diluted gas and cool it down in an extreme way, it becomes neither liquid nor solid, but remains gaseous.

Despite this, the particles do lose more and more energy. Below a certain critical temperature, the quantum properties of these particles become so dominant that what is known as a Bose-Einstein condensate is formed. In this condensate, the individual atoms are completely delocalized. This means that the same atom is present at any point in the condensate at any given time. Consequently, Bose-Einstein condensates are also superfluids.

Francesca Ferlainos team used the Bose-Einstein condensate two years ago to create one-dimensional supersolids. The researchers got magnetic atoms to organize themselves into droplets in the ultracold quantum gas and rearrange themselves as crystals. However, all particles still delocalized across all of the droplets, so the gas remained superfluid. The combination of the crystal structure with simultaneous superfluidity is called suprasolid or supersolid. Now scientists have succeeded in extending this phenomenon to two dimensions. They have managed to create systems with two or more rows of droplets.

This breakthrough significantly broadens the perspectives for research. In a two-dimensional suprasolid system, for example, it is possible to study how vortices form in the gap between several adjacent droplets. These vortices have been defined in theory but had not yet been demonstrated in practice. Yet they are an important consequence of superfluidity.

So far, vortices have only been observed in uniform superfluids and in quantized forms. A quantized vortex is basically a hole in the system, and then the superfluid circulates around this hole with a certain amount of rotation, explains Matthew Norcia of the research team. But in supersolids, the vortices should not be quantified in this way. And they should be found in low-density regions. Thats between droplets, not within a droplet where the atomic density is high.

A quantized vortex is basically a hole in the system, and then the superfluid circulates around this hole with a certain amount of rotation, Matthew Norcia

When researchers talk about quantized vortices in superfluid systems, they are talking specifically about the momentum impulse per particle. This is a unique property of the superfluid that stems from a quantum mechanical treatment of the system. Norcia: We assume that these quantum conditions are relaxed in supersolids. And in such a way that the momentum impulse per particle associated with a vortex can vary, depending on how the density of the state is modulated. So, if we look at the momentum impulse of these quantized vortices, we may have a measure of just how superfluid different supersolids are.

However, observing the phenomena of supersolids in quantum gas promises even more insights for research. This is because some important properties of supersolids can only be studied in two dimensions. For example, the rotational properties of a suprafluid can differ drastically from those of a normal fluid or a different system. Similarly, quantities such as viscosity, for which superfluids are unique, only make sense in systems with more than one dimension.

Nevertheless, these findings also help researchers explore the effects of symmetries. Norcia: When crystalline structures and superfluidity occur simultaneously in supersolids, it relates to the combination of translational and phase symmetries that are each broken in a supersolid. A comprehensive understanding of symmetries is critical to physics in general and to materials systems in particular. In this sense, studying the effects of these symmetries can help us better understand other physics systems. Both in the laboratory and in terms of practical applications.

Back in 2017, several research groups undertook similar experiments with lasers and quantum gases made up of sodium or rubidium atoms. The atoms were coupled to periodic structures excited by laser light. That is, the crystalline structure of the atom state was determined by the laser light. The result was that the supersolid that was produced was extremely rigid. This is because laser light does not support the oscillations of the crystalline structure of solids. By contrast, in the case of the magnetic atoms that the Austrian scientists used, it is the direct magnetic interaction between the atoms that causes the density to modulate. This allows the supersolid to be compress and vibrate. It is also this interaction, in combination with the drop potential, that determines the crystalline fraction.

Also interesting: Physicists develop an interface for quantum computers

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Matter that is both solid and liquid helps classical physics advance - Innovation Origins

A multidisciplinary, multi-institutional program led by The Ohio State University is taking the next step in its aim to develop a diverse, effective and contemporary quantum-ready workforce by revolutionizing and creating more equitable pathways to quantum science education.

QuSTEAM: Convergence Undergraduate Education in Quantum Science, Technology, Engineering, Arts and Mathematics, was awarded a $5 million cooperative agreement over a two-year period from the National Science Foundations (NSF) Convergence Accelerator. Following QuSTEAMs initial assessment period, Phase I, the award will fund Phase IIs objective to build transformative, modular quantum science degree and certification programs.

I know from personal experience that collaboration is the key to scientific success. Working across disciplines especially when it comes to the highly complex and multidisciplinary world of quantum science research will help us more quickly harness the enormous power of this emerging field and deliver real-world results more quickly and efficiently, said Ohio State President Kristina M. Johnson. As an added bonus, this project enables Ohio State to further part of its core mission, which is to educate the next generation of researchers through educational opportunities that advance diversity and workforce development.

The rapidly evolving field of quantum information science will enable technological breakthroughs and have far-reaching economic and societal impacts what researchers at the National Institute of Standards and Technology refer to as the second quantum revolution. Ohio State is emerging as a key leader in pushing the field forward, recently joining the Chicago Quantum Exchange, a growing intellectual hub for the research and development of quantum technology, as its first regional partner.

NSFs Convergence Accelerator is focused on accelerating solutions toward societal impact. Within three years, funded teams are to deliver high-impact results, which is fast for product development, said Douglas Maughan, head of the NSF Convergence Accelerator program. During Phase II, QuSTEAM and nine other 2020 cohort teams will participate in an Idea-to-Market curriculum to assist them in developing their solution further and to create a sustainability plan to ensure the effort provides a positive impact beyond NSF funding.

QuSTEAM is a great example of how universities and industry can work together to build the foundation for a strong, diverse workforce, said David Awschalom, the director of the Chicago Quantum Exchange andLiew Family Professor in Molecular Engineering and Physics at the University of Chicago. Innovations in this field require us to provide broadly accessible quantum education, and QuSTEAM represents an ambitious approach to training in quantum engineering.

Unlocking that potential, however, also requires a foundational shift in teaching and growing a quantum-literate workforce. QuSTEAM brings together scientists and educators from over 20 universities, national laboratories, community colleges, and historically Black colleges and universities (HBCUs) to develop a research-based quantum education curriculum and prepare the next generation of quantum information scientists and engineers. The initiative also has over 14 industrial partners, including GE Research, Honda and JPMorgan Chase, and collaborates with leading national research centers to help provide a holistic portrait of future workforce needs.

We have leaders in quantum information and STEM education, and both of these groups independently do good work building undergraduate curriculum, but they actually work together surprisingly rarely, said QuSTEAM lead investigator Ezekiel Johnston-Halperin, professor in the Department of Physics at Ohio State. We are talking to people in industry and academia about what aspects of quantum information are most critical, what skills are needed, what workforce training looks like today and what they expect it to look like a couple years from now.

We feel strongly about the need for redesigning quantum science education, which is the objective of QuSTEAM, said Marco Pistoia, head of the Future Lab for Applied Research and Engineering (FLARE) at JPMorgan Chase. The complexity of the quantum computing stack is enabling the creation of many new job opportunities. It is crucial for quantum curricula nationwide to collectively support this multiplicity of needs, but for this to happen, quantum scientists and engineers must have the proper training. We are very excited to see the impact of QuSTEAMs work in the near and long term, considering finance is predicted to be the first industry sector to start realizing significant value from quantum computing.

QuSTEAM is headed by five Midwestern universities: lead institution Ohio State, the University of Chicago, the University of Michigan, Michigan State University and the University of Illinois at Urbana-Champaign, all of which have partnered with local community colleges and regional partners with established transfer pipelines to engage underrepresented student populations.

The group is also collaborating with the IBM-HBCU Quantum Center to recruit faculty from its network of over 20 partner colleges and universities, as well as Argonne National Laboratory. In all, the QuSTEAM team comprises 66 faculty who share expertise in quantum information science and engineering, creative arts and social sciences, and education research.

To best develop a quantum-ready workforce, QuSTEAM identified the establishment of a common template for an undergraduate minor and associate certificate programs as the near-term priority. The team will build curricula consisting of in-person, online and hybrid courses for these degree and certification programs including initial offerings of the critical classes and modules at the respective universities while continuing to assess evolving workforce needs.

QuSTEAM plans to begin offering classes in spring 2022, with a full slate of core classes for a minor during the 2022-2023 academic year. The modular QuSTEAM curriculum will provide educational opportunities for two- and four-year institutions, minority-serving institutions and industry, while confronting and dismantling longstanding biases in STEM education.

If we want to increase diversity in quantum science, we need to really engage meaningfully with community colleges, minority-serving institutions and other small colleges and universities, Johnston-Halperin said. The traditional STEM model builds a program at an elite, R1 university and then allows the content to diffuse out from there. But historically this means designing it for a specific subset of students, and everything else is going to be a retrofit. Thats just never as effective.

QuSTEAM leverages integrated university support from faculty and staff from the Drake Institute for Teaching and Learning, the Institute for Materials Research, the Department of Physics and the Ohio State Office of Research.

Johnston-Halperin is joined at Ohio State by QuSTEAM co-PI Andrew Heckler, professor of physics and physics education research specialist. Other Ohio State faculty included on QuSTEAM are Daniel Gauthier, professor in the Department of Physics; Christopher Porter, postdoctoral researcher in the Department of Physics; David Penneys, associate professor in the Department of Mathematics; Zahra Atiq, assistant professor of practice of computer science and engineering in the College of Engineering; David Delaine and Emily Dringenberg, assistant professors of engineering education in the College of Engineering; and Edward Fletcher, associate professor of educational studies in the College of Education and Human Ecology.

QuSTEAM is one of 10 teams selected for two-year, $5 million Phase II funding as part the NSF Convergence Accelerator 2020 Cohort, which supports efforts to fast-track transitions from basic research and discovery into practice, and seeks to address national-scale societal challenges. With this funding, QuSTEAM will address the challenge of developing a strong national quantum workforce by instituting high-quality, engaging courses and educational tracks that allow for students of all backgrounds and interests to choose multiple paths of scholarship.

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Ohio State-led QuSTEAM initiative awarded $5 million from NSF - The Ohio State University News

Published by Google Researchers A study On the ArXiv server, they deny physics using the companys Sycamore quantum computer, claiming that they created time crystals or time crystals, but it is not clear how important this is. Discovery.

A crystal constant of time is also in constant flow, with fixed conditions repeated at predictable intervals without loss of energy. In other words, these crystals omit one of the most important laws of physics, the second law of thermodynamics, which states that the disturbance or entropy of an isolated system must always increase. Despite the constant flux state, they remain stable by resisting any irregular dissolution.

Well, these crystals do not have to be new, they were included in the 2012 Nobel Prize in Physics winner Frank Wilzek.

It was a big surprise, said Kurt von Keiserling, a physicist at the University of Birmingham in the UK who did not participate in the study. If you asked someone 30, 20 or 10 years ago, they wouldnt expect it.

Basically, a crystal of time is like a pendulum that never stops swinging.

Even if you completely separate a pendulum from the universe, if there is no friction and no air resistance, it will eventually stop, because it is the second law of thermodynamics, said Achilles Lazarides, a physicist at the University of Loughborough in the UK, who was one of the first scientists to discover the theoretical possibility of a new phase in 2015.

The theoretical novelty of crystals is, in some respects, a double-edged sword, as physicists are currently struggling to find ways to use them, although von Keiserling suggested that they could be used as high-precision sensors. Other proposals include the use of crystals for better memory storage or for the development of quantum computers with even faster processing power.

But the greatest use for time crystals may already be here. These will allow scientists to explore the limits of quantum mechanics.

It not only allows you to learn what is happening in nature, but also to design and look at what is actually happening Quantum Mechanics It allows you to do what you do not do, Lazarides said.

If you can not find something in nature, it does not mean it does not exist, because we created one of these, he added.

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Google's latest discovery changes the laws of physics - SwordsToday.ie

Whenever we examine the universe in a scientific manner, there are a few assumptions that we take for granted as we go about our investigations. We assume that the measurements that register on our devices correspond to physical properties of the system that we are observing. We assume that the fundamental properties, laws, and constants associated with the material universe do not spontaneously change from moment to moment. And we also assume, for many compelling reasons, that although the environment may vary from location to location, the rules that govern the universe always remain the same.

But every assumption, no matter how well-grounded it may be or how justified we believe we are in making it, has to be subject to challenge and scrutiny. Assuming that atoms behave the same everywhere at all times and in all places is reasonable, but unless the universe supports that assumption with convincing, high-precision evidence, we are compelled to question any and all assumptions. If the fundamental constants are identical at all times and places, the universe should show us that atoms behave the same everywhere we look. But do they? Depending on how you ask the question, you might not like the answer. Here is the story behind the fine-structure constant, and why it might not be constant, after all.

When most people hear the idea of a fundamental constant, they think about the constants of nature that are inherent to our reality. Things like the speed of light, the gravitational constant, or Plancks constant (the fundamental constant of the quantum universe) are often the first things we think of, along with the masses of the various indivisible particles in the universe. In physics, however, these are what we call dimensionful constants, which means that they rely on our definitions of quantities like mass, length, or time.

An alternative way to conceive of these constants is to make them dimensionless instead: so that arbitrary definitions like kilogram, meter, or second make no difference to the constant. In this conception, each quantum interaction has a coupling strength associated with it, and the coupling of the electromagnetic interaction is known as the fine-structure constant and is denoted by the symbol alpha (). Fascinatingly enough, its effects were detected before quantum physics was even remotely understood, and remained wholly unexplained for nearly 30 years.

In 1887, arguably the greatest null result in the history of physics was obtained, via the Michelson-Morley experiment. The experiment was brilliant in conception, seeking to measure the speed of Earth through the rest frame of the universe by:

Michelson originally performed a version of this experiment by himself back in 1881, detecting no effect but recognizing the need to improve the experiments precision.

Six years later, the Michelson-Morley experiment represented an improvement by more than a factor of ten, making it the most precise electromagnetic measuring device at the time. While again, no shift was detected, demonstrating no need for the hypothesized aether, the apparatus they developed was also spectacular for measuring the spectrum of light emitted by various atoms. Puzzlingly, where a single emission line was expected to occur at a specific wavelength, sometimes there was just a single line, but at other times there were a series of narrowly-spaced emission lines, providing empirical evidence (but without a theoretical motivation) for a finer-than-expected structure to atoms.

What is actually happening became clearer with the development of modern quantum mechanics. Electrons orbit around the atomic nucleus in fixed, quantized energy levels only, and it is known that they can occupy different orbitals, which correspond to different values of orbital angular momentum. These are required to balance by both relativity and quantum physics. First derived by Arnold Sommerfeld in 1916, it was recognized that these narrowly-spaced lines were an example of splitting due to the fine-structure of atoms, with hyperfine structure from electron/nucleon interactions discovered shortly thereafter.

Today, we understand the fine-structure constant in the context of quantum field theory, where it is the probability of an interacting particle having what we call a radiative correction: emitting or absorbing an electromagnetic quantum (that is, a photon) during an interaction. We typically measure the fine-structure constant, , at todays negligibly low energies, where it has a value that is equal to 1/137.0359991, with an uncertainty of ~1 in the final digit. It is defined as a dimensionless combination of dimensionful physical constants: the elementary charge squared divided by Plancks constant and the speed of light, and the value we measure today is consistent across all sufficiently precise experiments.

At high energies in particle physics experiments, however, we notice that the value of gets stronger at higher energies. As the energy of the interacting particle(s) increases, so does the strength of the electromagnetic interaction. When the universe was very, very hot such as at energies achieved just ~1 nanosecond after the Big Bang the value of was more like 1/128, as particles like the Z-boson, which can only exist virtually at todays low energies, can more easily be physically real at higher energies. The interaction strength is expected to scale with energy, an instance where our theoretical predictions and our experimental measurements match up remarkably well.

However, there is an entirely different way to measure the fine-structure constant at todays low energies: by measuring spectral lines, or emission and absorption features, from distant light sources throughout the cosmos. As background light from a source strikes the intervening matter, some portion of that light is absorbed at specific wavelengths. The exact wavelengths that are observed depend on a number of factors, such as the redshift of the source but also on the value of the fine-structure constant.

If there are any variations in , either over time or directionally in space, a careful examination of spectral features from a wide variety of astrophysical sources, particularly if they span many billions of years in time (or billions of light-years in distance), could reveal those variations. The most straightforward way to look for these variations is through quasar absorption spectroscopy: where the light quasars, the brightest individual sources in the universe, encounter every intervening cloud of matter that exists between the emitter (the quasar itself) and the observer (us, here on Earth).

There are very intricate, precise energy levels that exist for both normal hydrogen (with an electron bound to a proton) and its heavy isotope deuterium (with an electron bound to a deuteron, which contains both a proton and a neutron), and these energy levels are just slightly different from one another. If you can measure the spectra of these different quasars and look for these precise, very-slightly-different fine and hyperfine transitions, you would be able to measure at the location of the quasar.

If the laws of physics were the same everywhere throughout the universe, then based on the observed properties of these lines, which includes:

you would expect to be able to infer the same value of everywhere. The only difference you would anticipate would be redshift-dependent, where all the wavelengths for a specific absorber would be systematically shifted by the same redshift-dependent factor.

Yet, that is not what we see. Everywhere we look in the universe at every quasar and every example of fine or hyperfine structure in the intervening, absorptive gas clouds we see that there are tiny, minuscule, but non-negligible shifts in those transition ratios. At the level of a few parts-per-million, the value of the fine-structure constant, , appears to observationally vary. What is remarkable is that this variation was not expected or anticipated but has robustly shown up, over and over again, in quasar absorption studies going all the way back to 1999.

Beginning in 1999, a team of astronomers led by Australian astrophysicist John K. Webb started seeing evidence that was different from different astronomical measurements. Using the Keck telescopes and over 100 quasars, they found that was smaller in the past and had risen by approximately 6 parts-per-billion over the past ~10 billion years. Other groups were unable to verify this, however, with complementary observations from the Very Large Telescope showing the exact opposite effect: that the fine-structure constant, , was larger in the past, and has been slowly decreasing ever since.

Subsequently, Webbs team obtained more data with greater numbers of quasars, spanning larger fractions of the sky and cutting across cosmic time. A simple time-variation was no longer consistent with the data, as variations were inconsistent from place-to-place and did not scale directly with either redshift or direction. Overall, there were some places where appeared larger than average and others where it appeared smaller, but there was no overall pattern. Even with the latest 2021 data, the few-parts-in-a-million variations that are seen are inconclusive.

It is often said that extraordinary claims require extraordinary evidence, but the uncertainties associated with each of these measurements were at least as large as the suspected signal itself: a few parts-per-million. In 2018, however, a remarkable study even though it was only of one system had the right confluence of properties to be able to measure , at a distance of 3.3 billion light-years away, to a precision of just ~1 part-per-million.

Instead of looking at hydrogen and deuterium, isotopes of the same element with the same nuclear charges but different nuclear masses, researchers using the Arecibo telescope in one of its last major discoveries found two absorption lines of a hydroxyl (OH-) ion: at 1720 and 1612 megahertz in frequency around a rare and peculiar blazar. These absorption lines have different dependencies on the fine-structure constant, , as well as the proton-to-electron mass ratio, and yet these measurements combine to show a null result: consistent with no variation over the past ~3 billion years. These are, to date, the most stringent constraints on tiny changes in the fine-structure constants value from astronomy, consistent with no effect at all.

The observational techniques that have been pioneered in quasar absorption spectroscopy have allowed us to measure these atomic profiles to unprecedented precision, creating a puzzle that remains unsolved to this day: why do quasars appear to show small but significant differences in the inferred value of the fine-structure constant between them? We know there has been no significant variation over the past ~3 billion years, from not only astronomy but from the Oklo natural nuclear reactor as well. In addition, the value is not changing today to 17 decimal places, as constrained by atomic clocks.

It remains possible that the fundamental constants did actually vary a long time ago, or that they varied differently in different locations in space. To untangle whether that is the case or not, however, we first have to understand what is causing the observed variations in quasar absorption lines, and that remains an unsolved puzzle that could just as easily be due to an unidentified error as it is to a physical cause. Until there is a confluence of evidence, where many disparate observations all come together to point to the same consistent conclusion, the default assumption must remain that the fundamental constants really are constant.

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Could fundamental physical constants not be constant across space and time? - Big Think

Physicists have created the first-ever atomic vortex beam a swirling tornado of atoms and molecules with mysterious properties that have yet to be understood.

By sending a straight beam of helium atoms through a grating with teeny slits, scientists were able to use the weird rules of quantum mechanics to transform the beam into a whirling vortex.

The extra gusto provided by the beam's rotation, called orbital angular momentum, gives it a new direction to move in, enabling it to act in ways that researchers have yet to predict. For instance, they believe the atoms' rotation could add extra dimensions of magnetism to the beam, alongside other unpredictable effects, due to the electrons and the nuclei inside the spiraling vortex atoms spinning at different speeds.

Related: The 18 biggest unsolved mysteries in physics

"One possibility is that this could also change the magnetic moment of the atom," or the intrinsic magnetism of a particle that makes it act like a tiny bar magnet, study co-author Yair Segev, a physicist at the University of California, Berkeley, told Live Science.

In the simplified, classical picture of the atom, negatively-charged electrons orbit a positively-charged atomic nucleus. In this view, Segev said that as the atoms spin as a whole, the electrons inside the vortex would rotate at a faster speed than the nuclei, "creating different opposing [electrical] currents" as they twist. This could, according to the famous law of magnetic induction outlined by Michael Faraday, produce all kinds of new magnetic effects, such as magnetic moments that point through the center of the beam and out of the atoms themselves, alongside more effects that they cannot predict.

The researchers created the beam by sending helium atoms through a grid of tiny slits each just 600 nanometers across. In the realm of quantum mechanics the set of rules which govern the world of the very small atoms can behave both like particles and tiny waves; as such, the beam of wave-like helium atoms diffracted through the grid, bending so much that they emerged as a vortex that corkscrewed its way through space.

The whirling atoms then arrived at a detector, which showed multiple beams diffracted to differing extents to have varying angular momentums as tiny little doughnut-like rings imprinted across it. The scientists also spotted even smaller, brighter doughnut rings wedged inside the central three swirls. These are the telltale signs of helium excimers a molecule formed when one energetically excited helium atom sticks to another helium atom. (Normally, helium is a noble gas and doesn't bind with anything.)

The orbital angular momentum given to atoms inside the spiraling beam also changes the quantum mechanical "selection rules" that determine how the swirling atoms will interact with other particles, Segev said. Next, the researchers will smash their helium beams into photons, electrons and atoms of elements besides helium to see how they might behave.

If their rotating beam does indeed act differently, it could become an ideal candidate for a new type of microscope that can peer into undiscovered details on the subatomic level. The beam could, according to Segev, give us more information on some surfaces by changing the image that is imprinted upon the beam atoms bounced off it.

"I think that as is often the case in science, it's not a leap of capability that leads to something new, but rather a change in perspective," Segev said.

The researchers published their findings Sept. 3 in the journal Science.

Originally published on Live Science.

Link:

1st 'atom tornado' created from swirling vortex of helium atoms - Livescience.com