Monthly Archives: April 2022

We will study about Quantum Physics and Classical physics, Newtons laws of motion can explain the behaviour of macroscopic objects or objects that are at a scale of human interaction and experience, even including astronomical objects. But classical physics isnt able to explain the behaviour of macroscopic objects or objects that are at a scale of an atom.

This is mainly because the behaviour of macroscopic objects is practically particle in nature, they do have wave nature but it is negligible because of their huge masses; whereas on the other hand the atomic level particles have very little mass and hence both particle and wave nature is prevalent in them. This dual behaviour of displaying both particle and wave nature is known as dual behaviour of matter and for every particle, the particle nature comes from its mass and the wave nature comes from its matter-wave defined by De-Broglie relationship which is given by,

=

(begin{array}{l} frac {h}{mv}end{array} )

Where,

= wavelength of the matter

h = planks constant

m = mass of the matter

v = velocity of matter

Classical Physics hasnt been able to explain the dual behaviour of a matter and Heisenbergs uncertainty principle, according to which the position and momentum of a sub-atomic particle can be calculated simultaneously with some degree of inaccuracy. Hence, there was a need for a new theory that could explain the behaviour of atomic and sub-atomic particles.

So, this led to the birth of quantum physics It is a branch of science that explains the physical phenomenon by microscopic and atomic approach and takes into account the dual behaviour of matter. It is theoretical physics and it specifies the laws of motion that the microscopic objects obey. When quantum mechanics is applied to macroscopic objects (for which wave-like properties are insignificant) the results are the same as those from classical mechanics.

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Quantum Physics - Definition & Formula | Classical Physics | Dual Behaviour ...

There is a worldwide research effort exploring the potentials of quantum mechanics for applications. The field began with Feynmans proposal in 1981 at MIT Endicott House to build a computer that takes advantage of quantum mechanics and has grown enormously since Peter Shors 1994 quantum factoring algorithm. The idea of utilizing quantum mechanics to process information has since grown from computation and communication to encompass diverse topics such as sensing and simulations in biology and chemistry. Leaving aside the extensive experimental efforts to build controllable large-scale quantum devices, theory research in quantum information science (QIS) investigates several themes:

QIS theory research at MIT spans all of these areas. The CTP faculty involved are: Soonwon Choi and Aram Harrow, and the larger group at MIT includes Isaac Chuang (EECS/physics), Seth Lloyd (Mech. Eng.), Anand Natarajan (EECS) and Peter Shor (Math). Other faculty in the area include Eddie Farhi (emeritus), Jeffrey Goldstone (emeritus) and Jeff Shapiro (EECS, emeritus). Together this forms a large and vibrant group working in all areas of QIS.

Some of the notable contributions involving the CTP include the quantum adiabatic algorithm and quantum walk algorithms (Farhi, Goldstone), the first example of a problem for which quantum computers exhibit no speedup (Farhi, Goldstone), proposals for unforgeable quantum money (Farhi, Shor), a quantum algorithm for linear systems of equations (Harrow, Lloyd), efficient protocols for simulating quantum channels (Harrow, Shor), both algorithms and hardness results for testing entanglement (Harrow), proposals for quantum approximate optimization algorithms (Farhi, Goldstone), proposals and experimental observations of exotic quantum dynamics such as slow thermalization or a discrete time crystalline phase in quantum simulators (Choi), quantum sensing protocols using strongly interacting spin ensembles (Choi), and quantum convolutional neural networks (Choi). Ongoing research at MIT in QIS includes work on new quantum algorithms, efficient simulations of quantum systems, methods to characterize and control existing or near-term quantum hardwares, connections to many-body physics, applications in high-energy physics, and many other topics.

The larger QIS group at MIT shares a seminar series, a weekly group meeting, regular events for grad students.

Interdepartmental course offerings include an introductory and an advanced class in core QI/QC, as well as occasional advanced special topics classes. Quantum information has also entered the undergraduate physics curriculum with a junior lab experiment on NMR quantum computing and some lectures in the 8.04/8.05/8.06 sequence on quantum computing.

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Quantum Information Science - MIT Physics

Physicists have found that an elementary particle called the W boson appears to be 0.1% too heavy a tiny discrepancy that could foreshadow a huge shift in fundamental physics.

The measurement, reported today in the journal Science, comes from a vintage particle collider at the Fermi National Accelerator Laboratory in Batavia, Illinois, that smashed its final protons a decade ago. The roughly 400 members of the Collider Detector at Fermilab (CDF) collaboration have continued to analyze W bosons produced by the collider, called the Tevatron, chasing down myriad sources of error to reach an unparalleled level of precision.

If the Ws excess heft relative to the standard theoretical prediction can be independently confirmed, the finding would imply the existence of undiscovered particles or forces and would bring about the first major rewriting of the laws of quantum physics in half a century.

This would be a complete change in how we see the world, potentially even rivaling the 2012 discovery of the Higgs boson in significance, said Sven Heinemeyer, a physicist at the Institute for Theoretical Physics in Madrid who is not part of CDF. The Higgs fit well into the previously known picture. This one would be a completely new area to be entered.

The finding comes at a time when the physics community hungers for flaws in the Standard Model of particle physics, the long-reigning set of equations capturing all known particles and forces. The Standard Model is known to be incomplete, leaving various grand mysteries unsolved, such as the nature of dark matter. The CDF collaborations strong track record makes their new result a credible threat to the Standard Model.

Theyve produced hundreds of beautiful measurements, said Aida El-Khadra, a theoretical physicist at the University of Illinois, Urbana-Champaign. Theyre known to be careful.

But no one is popping champagne yet. While the new W mass measurement, taken alone, departs starkly from the Standard Models prediction, other experiments weighing the W have produced less dramatic (albeit less precise) results. In 2017, for instance, the ATLAS experiment at Europes Large Hadron Collider measured the W particles mass and found it to be only a hair heavier than what the Standard Model says. The clash between CDF and ATLAS suggests that one or both groups has overlooked some subtle quirk of their experiments.

I would like it to be confirmed and to understand the difference from prior measurements, said Guillaume Unal, a physicist at CERN, the laboratory that houses the Large Hadron Collider, and a member of the ATLAS experiment. The W boson has to be the same on both sides of the Atlantic.

Its a monumental piece of work, said Frank Wilczek, a Nobel Prize-winning physicist at the Massachusetts Institute of Technology, but its very hard to know what to do with it.

W bosons, together with Z bosons, mediate the weak force, one of the universes four fundamental forces. Unlike gravity, electromagnetism and the strong force, the weak force doesnt push or pull so much as it transforms heavier particles into lighter ones. A muon spontaneously decays into a W boson and a neutrino, for instance, and the W then becomes an electron and another neutrino. Related subatomic shape-shifting causes radioactivity and helps keep the sun shining.

Assorted experiments have measured the W and Z bosons masses over the last 40 years. The W bosons mass has proved an especially alluring target. Whereas other particle masses must simply be measured and accepted as facts of nature, the W mass can be predicted by combining a handful of other measurable quantum properties in the Standard Model equations.

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Fermilab Says Particle Is Heavy Enough to Break the Standard Model - Quanta Magazine

Peter Morgan; Yale University, Department of Physics

Abstract: The connection between classical mechanics and quantum mechanics has historically been dominated by quantization and, in the opposite direction, the correspondence principle and Ehrenfest's theorem, which fall far short of the clarity of isomorphisms between mathematical structures. In contrast, we can use Koopman's Hilbert space formalism for classical mechanics to construct isomorphisms between classical and quantum Hilbert spaces and between classical and quantum algebras of operators, which allows a unified approach to joint and incompatible measurements. With a common measurement theory in place, other differences between classical and quantum can be more clearly described. At the level of field theories, signal analysis can be adopted as an empiricist way to unify QFT and random fields, which allows a carefully judged classical intuition to suggest several ways to rethink QFT.

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Math Physics Seminar - Peter Morgan | Physics and Astronomy | The University of Iowa - The University of Iowa

Almost 400 years ago, in The Assayer, Galileo wrote: Philosophy is written in this grand book, the universe [But the book] is written in the language of mathematics. He was much more than an astronomer, and this can almost be thought of as the first writing on the scientific method.

We do not know who first started applying mathematics to scientific study, but it is plausible that it was the Babylonians, who used it to discover the pattern underlying eclipses, nearly 3,000 years ago. But it took 2,500 years and the invention of calculus and Newtonian physics to explain the patterns.

Since then, probably every single major scientific discovery has used mathematics in some form, simply because it is far more powerful than any other human language. It is not surprising that this has led many people to claim that mathematics is much more: that the universe is created by a mathematician.

So could we imagine a universe in which mathematics does not work?

The Sapir-Whorf hypothesis asserts that you cannot discuss a concept unless you have the language to describe it.

In any science, and physics in particular, we need to describe concepts that do not map well on to any human language. One can describe an electron, but the moment we start asking questions like What colour is it? we start to realize the inadequacies of English.

The colour of an object depends on the wavelengths of light reflected by it, so an electron has no colour, or more accurately, all colours. The question itself is meaningless. But ask How does an electron behave? and the answer is, in principle, simple. In 1928, Paul A.M. Dirac wrote down an equation that describes the behaviour of an electron almost perfectly under all circumstances. This does not mean it is simple when we look at the details.

For example, an electron behaves as a tiny magnet. The magnitude can be calculated, but the calculation is horrendously complicated. Explaining an aurora, for example, requires us to understand orbital mechanics, magnetic fields and atomic physics, but at heart, these are just more mathematics.

But it is when we think of the individual that we realize that a human commitment to logical, mathematical thinking goes much deeper. The decision to overtake a slow-moving car does not involve the explicit integration of the equations of motion, but we certainly do it implicitly. A Tesla on autopilot will actually solve them explicitly.

So we really should not be surprised that mathematics is not just a language for describing the external world, but in many ways the only one. But just because something can be described mathematically does not mean it can be predicted.

One of the more remarkable discoveries of the last 50 years has been the discovery of chaotic systems. These can be apparently simple mathematical systems that cannot be solved precisely. It turns out that many systems are chaotic in this sense. Hurricane tracks in the Caribbean are superficially similar to eclipse tracks, but we cannot predict them precisely with all the power of modern computers.

However, we understand why: the equations that describe weather are intrinsically chaotic, so we can make accurate predictions in the short term, (about 24 hours), but these become increasingly unreliable over days. Similarly, quantum mechanics provides a theory where we know precisely what predictions cannot be made precisely. One can calculate the properties of an electron very accurately, but we cannot predict what an individual one will do.

Hurricanes are obviously intermittent events, and we cannot predict when one will happen in advance. But the mere fact that we cannot predict an event precisely does not mean we cannot describe it when it happens. We can even handle one-off events: it is generally accepted that the universe was created in the Big Bang and we have a remarkably precise theory of that.

A whole host of social phenomena, from the stock market to revolutions, lack good predictive mathematics, but we can describe what has happened and to some extent construct model systems.

So how about personal relationships? Love may be blind, but relationships are certainly predictable. The vast majority of us choose partners inside our social class and linguistic group, so there is absolutely no doubt that is true in the statistical sense. But it is also true in the local sense. A host of dating sites make their money by algorithms that at least make some pretence at matching you to your ideal mate.

A universe that could not be described mathematically would need to be fundamentally irrational and not merely unpredictable. Just because a theory is implausible does not mean we could not describe it mathematically.

But I do not think we live in that universe, and I suspect we cannot imagine a non-mathematical universe.

This article by Peter Watson, Emeritus professor, Physics, Carleton University, is republished from The Conversation under a Creative Commons license. Read the original article.

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Why mathematics is essential to understanding our universe - The Next Web

Abstract artists concept of neutrino particles.

Physicists are closing in on the true nature of the neutrino and might be closer to answering a fundamental question about our own existence.

In a Laboratory under a mountain, physicists are using crystals far colder than frozen air to study ghostly particles, hoping to learn secrets from the beginning of the universe. Researchers at the Cryogenic Underground Observatory for Rare Events (CUORE) announced this week that they had placed some of the most stringent limits yet on the strange possibility that the neutrino is its own antiparticle. Neutrinos are deeply unusual particles, so ethereal and so ubiquitous that they regularly pass through our bodies without us noticing. CUORE has spent the last three years patiently waiting to see evidence of a distinctive nuclear decay process, only possible if neutrinos and antineutrinos are the same particle. CUOREs new data shows that this decay doesnt happen for trillions of trillions of years, if it happens at all. CUOREs limits on the behavior of these tiny phantoms are a crucial part of the search for the next breakthrough in particle and nuclear physics and the search for our own origins.

CUORE scientists Dr. Paolo Gorla (LNGS, left) and Dr. Lucia Canonica (MIT, right) inspect the CUORE cryogenic systems. Credit: Yury Suvorov and the CUORE Collaboration

Ultimately, we are trying to understand matter creation, said Carlo Bucci, researcher at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy and the spokesperson for CUORE. Were looking for a process that violates a fundamental symmetry of nature, added Roger Huang, a postdoctoral researcher at the Department of Energys Lawrence Berkeley National Laboratory (Berkeley Lab) and one of the lead authors of the new study.

CUORE Italian for heart is among the most sensitive neutrino experiments in the world. The new results from CUORE are based on a data set ten times larger than any other high-resolution search, collected over the last three years. CUORE is operated by an international research collaboration, led by the Istituto Nazionale di Fisica Nucleare (INFN) in Italy and Berkeley Lab in the US. The CUORE detector itself is located under nearly a mile of solid rock at LNGS, a facility of the INFN. U.S. Department of Energy-supported nuclear physicists play a leading scientific and technical role in this experiment. CUOREs new results were published on April 6, 2022, in Nature.

Neutrinos are everywhere there are trillions of neutrinos passing through your thumbnail alone as you read this sentence. They are invisible to the two strongest forces in the universe, electromagnetism and the strong nuclear force, which allows them to pass right through you, the Earth, and nearly anything else without interacting. Despite their vast numbers, their enigmatic nature makes them very difficult to study, and has left physicists scratching their heads ever since they were first postulated over 90 years ago. It wasnt even known whether neutrinos had any mass at all until the late 1990s as it turns out, they do, albeit not very much.

One of the many remaining open questions about neutrinos is whether they are their own antiparticles. All particles have antiparticles, their own antimatter counterpart: electrons have antielectrons (positrons), quarks have antiquarks, and neutrons and protons (which make up the nuclei of atoms) have antineutrons and antiprotons. But unlike all of those particles, its theoretically possible for neutrinos to be their own antiparticles. Such particles that are their own antiparticles were first postulated by the Italian physicist Ettore Majorana in 1937, and are known as Majorana fermions.

CUORE detector being installed into the cryostat. Credit: Yury Suvorov and the CUORE Collaboration

If neutrinos are Majorana fermions, that could explain a deep question at the root of our own existence: why theres so much more matter than antimatter in the universe. Neutrinos and electrons are both leptons, a kind of fundamental particle. One of the fundamental laws of nature appears to be that the number of leptons is always conserved if a process creates a lepton, it must also create an anti-lepton to balance it out. Similarly, particles like protons and neutrons are known as baryons, and baryon number also appears to be conserved. Yet if baryon and lepton numbers were always conserved, then there would be exactly as much matter in the universe as antimatter and in the early universe, the matter and antimatter would have met and annihilated, and we wouldnt exist. Something must violate the exact conservation of baryons and leptons. Enter the neutrino: if neutrinos are their own antiparticles, then lepton number wouldnt have to be conserved, and our existence becomes much less mysterious.

The matter-antimatter asymmetry in the universe is still unexplained, said Huang. If neutrinos are their own antiparticles, that could help explain it.

Nor is this the only question that could be answered by a Majorana neutrino. The extreme lightness of neutrinos, about a million times lighter than the electron, has long been puzzling to particle physicists. But if neutrinos are their own antiparticles, then an existing solution known as the seesaw mechanism could explain the lightness of neutrinos in an elegant and natural way.

But determining whether neutrinos are their own antiparticles is difficult, precisely because they dont interact very often at all. Physicists best tool for looking for Majorana neutrinos is a hypothetical kind of radioactive decay called neutrinoless double beta decay. Beta decay is a fairly common form of decay in some atoms, turning a neutron in the atoms nucleus into a proton, changing the chemical element of the atom and emitting an electron and an anti-neutrino in the process. Double beta decay is more rare: instead of one neutron turning into a proton, two of them do, emitting two electrons and two anti-neutrinos in the process. But if the neutrino is a Majorana fermion, then theoretically, that would allow a single virtual neutrino, acting as its own antiparticle, to take the place of both anti-neutrinos in double beta decay. Only the two electrons would make it out of the atomic nucleus. Neutrinoless double-beta decay has been theorized for decades, but its never been seen.

The CUORE experiment has gone to great lengths to catch tellurium atoms in the act of this decay. The experiment uses nearly a thousand highly pure crystals of tellurium oxide, collectively weighing over 700 kg. This much tellurium is necessary because on average, it takes billions of times longer than the current age of the universe for a single unstable atom of tellurium to undergo ordinary double beta decay. But there are trillions of trillions of atoms of tellurium in each one of the crystals CUORE uses, meaning that ordinary double beta decay happens fairly regularly in the detector, around a few times a day in each crystal. Neutrinoless double beta decay, if it happens at all, is even more rare, and thus the CUORE team must work hard to remove as many sources of background radiation as possible. To shield the detector from cosmic rays, the entire system is located underneath the mountain of Gran Sasso, the largest mountain on the Italian peninsula. Further shielding is provided by several tons of lead. But freshly mined lead is slightly radioactive due to contamination by uranium and other elements, with that radioactivity decreasing over time so the lead used to surround the most sensitive part of CUORE is mostly lead recovered from a sunken ancient Roman ship, nearly 2000 years old.

Perhaps the most impressive piece of machinery used at CUORE is the cryostat, which keeps the detector cold. To detect neutrinoless double beta decay, the temperature of each crystal in the CUORE detector is carefully monitored with sensors capable of detecting a change in temperature as small as one ten-thousandth of a Celsius degree. Neutrinoless double beta decay has a specific energy signature and would raise the temperature of a single crystal by a well-defined and recognizable amount. But in order to maintain that sensitivity, the detector must be kept very cold specifically, its kept around 10 mK, a hundredth of a degree above absolute zero. This is the coldest cubic meter in the known universe, said Laura Marini, a research fellow at Gran Sasso Science Institute and CUOREs Run Coordinator. The resulting sensitivity of the detector is truly phenomenal. When there were large earthquakes in Chile and New Zealand, we actually saw glimpses of it in our detector, said Marini. We can also see waves crashing on the seashore on the Adriatic Sea, 60 kilometers away. That signal gets bigger in the winter, when there are storms.

Despite that phenomenal sensitivity, CUORE hasnt yet seen evidence of neutrinoless double beta decay. Instead, CUORE has established that, on average, this decay happens in a single tellurium atom no more often than once every 22 trillion trillion years. Neutrinoless double beta decay, if observed, will be the rarest process ever observed in nature, with a half-life more than a million billion times longer than the age of the universe, said Danielle Speller, Assistant Professor at Johns Hopkins University and a member of the CUORE Physics Board. CUORE may not be sensitive enough to detect this decay even if it does occur, but its important to check. Sometimes physics yields surprising results, and thats when we learn the most. Even if CUORE doesnt find evidence of neutrinoless double-beta decay, it is paving the way for the next generation of experiments. CUOREs successor, the CUORE Upgrade with Particle Identification (CUPID) is already in the works. CUPID will be over 10 times more sensitive than CUORE, potentially allowing it to glimpse evidence of a Majorana neutrino.

But regardless of anything else, CUORE is a scientific and technological triumph not only for its new bounds on the rate of neutrinoless double beta decay, but also for its demonstration of its cryostat technology. Its the largest refrigerator of its kind in the world, said Paolo Gorla, a staff scientist at LNGS and CUOREs Technical Coordinator. And its been kept at 10 mK continuously for about three years now. Such technology has applications well beyond fundamental particle physics. Specifically, it may find use in quantum computing, where keeping large amounts of machinery cold enough and shielded from environmental radiation to manipulate on a quantum level is one of the major engineering challenges in the field.

Meanwhile, CUORE isnt done yet. Well be operating until 2024, said Bucci. Im excited to see what we find.

Reference: Search for Majorana neutrinos exploiting millikelvin cryogenics with CUORE by The CUORE Collaboration, 6 April 2022, Nature.DOI: 10.1038/s41586-022-04497-4

CUORE is supported by the U.S. Department of Energy, Italys National Institute of Nuclear Physics (Instituto Nazionale di Fisica Nucleare, or INFN), and the National Science Foundation (NSF). CUORE collaboration members include: INFN, University of Bologna, University of Genoa, University of Milano-Bicocca, and Sapienza University in Italy; California Polytechnic State University, San Luis Obispo; Berkeley Lab; Johns Hopkins University; Lawrence Livermore National Laboratory; Massachusetts Institute of Technology; University of California, Berkeley; University of California, Los Angeles; University of South Carolina; Virginia Polytechnic Institute and State University; and Yale University in the US; Saclay Nuclear Research Center (CEA) and the Irne Joliot-Curie Laboratory (CNRS/IN2P3, Paris Saclay University) in France; and Fudan University and Shanghai Jiao Tong University in China.

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Physicists Are Closing In on the Next Breakthrough in Particle Physics And the Search for Our Own Origins - SciTechDaily