Category Archives: Quantum Physics

May 17, 2017 Experiments at TU Wien (Vienna) -- with a quantum chip, controlling a cloud of atoms. Credit: TU Wien

Quantum field theories are often hard to verify in experiments. Now, there is a new way of putting them to the test. Scientists have created a quantum system consisting of thousands of ultra cold atoms. By keeping them in a magnetic trap on an atom chip, this atom cloud can be used as a 'quantum simulator', which yields new insights into some of the most fundamental questions of physics.

What happened right after the beginning of the universe? How can we understand the structure of quantum materials? How does the Higgs-Mechanism work? Such fundamental questions can only be answered using quantum field theories. These theories do not describe particles independently from each other; all particles are seen as a collective field, permeating the whole universe.

But these theories are often hard to test in an experiment. At the Vienna Center for Quantum Science and Technology (VCQ) at TU Wien, researchers have now demonstrated how quantum field theories can be put to the test in new kinds of experiments. They have created a quantum system consisting of thousands of ultra cold atoms. By keeping them in a magnetic trap on an atom chip, this atom cloud can be used as a "quantum simulator", which yields information about a variety of different physical systems and new insights into some of the most fundamental questions of physics.

Complex Quantum SystemsMore than the Sum of their Parts

"Ultra cold atoms open up a door to recreate and study fundamental quantum processes in the lab", says Professor Jrg Schmiedmayer (VCQ, TU Wien). A characteristic feature of such a system is that its parts cannot be studied independently.

The classical systems we know from daily experience are quite different: The trajectories of the balls on a billiard table can be studied separatelythe balls only interact when they collide.

"In a highly correlated quantum system such as ours, made of thousands of particles, the complexity is so high that a description in terms of its fundamental constituents is mathematically impossible", says Thomas Schweigler, the first author of the paper. "Instead, we describe the system in terms of collective processes in which many particles take partsimilar to waves in a liquid, which are also made up of countless molecules." These collective processes can now be studied in unprecedented detail using the new methods.

Higher Correlations

In high-precision measurements, it turns out that the probability of finding an individual atom is not the same at each point in spaceand there are intriguing relationships between the different probabilities. "When we have a classical gas and we measure two particles at two separate locations, this result does not influence the probability of finding a third particle at a third point in space", says Jrg Schmiedmayer. "But in quantum physics, there are subtle connections between measurements at different points in space. These correlations tell us about the fundamental laws of nature which determine the behaviour of the atom cloud on a quantum level."

"The so-called correlation functions, which are used to mathematically describe these relationships, are an extremely important tool in theoretical physics to characterize quantum systems", says Professor Jrgen Berges (Institute for Theoretical Physics, Heidelberg University). But even though they have played an important part in theoretical physics for a long time, these correlations could hardly be measured in experiments. With the help of the new methods developed at TU Wien, this is now changing: "We can study correlations of different orders - up to the tenth order. This means that we can investigate the relation between simultaneous measurements at ten different points in space", Schmiedmayer explains. "For describing the quantum system, it is very important whether these higher correlations can be represented by correlations of lower orderin this case, they can be neglected at some pointor whether they contain new information."

Quantum Simulators

Using such highly correlated systems like the atom cloud in the magnetic trap, various theories can now be tested in a well-controlled environment. This allows us to gain a deep understanding of the nature of quantum correlations. This is especially important because quantum correlations play a crucial role in many, seemingly unrelated physics questions: Examples are the peculiar behaviour of the young universe right after the big bang, but also for special new materials, such as the so-called topological insulators.

Important information on such physical systems can be gained by recreating similar conditions in a model system, like the atom clouds. This is the basic idea of quantum simulators: Much like computer simulations, which yield data from which we can learn something about the physical world, a quantum simulation can yield results about a different quantum system that cannot be directly accessed in the lab.

The study is published in the journal Nature.

Explore further: Bell correlations measured in half a million atoms

More information: Experimental characterization of a quantum many-body system via higher-order correlations, Nature (2017). nature.com/articles/doi:10.1038/nature22310

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Testing quantum field theory in a quantum simulator - Phys.org - Phys.Org

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The Marriage Of Einstein's Theory Of Relativity And Quantum Physics Depends On The Pull Of Gravity Forbes As far as I know quantum physics and relativity theory will never get along. Does that mean one of them is basically wrong? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better ...

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The Marriage Of Einstein's Theory Of Relativity And Quantum Physics Depends On The Pull Of Gravity - Forbes

In Brief Scientists at the British University of Columbia have argued that constantly fluctuating space-time is responsible for universal expansion rather than dark energy. This may be an answer to one of the fundamental problems in cosmology. Einstein +Quantum Physics

Scientists at the University of British Columbia have proposed a radical new theory to explain the exponentially increasing size of the universe. Ultimately, it seeks to reconcile two different concepts in physics: Quantum Mechanics and Einsteins Theory of General Relativity. the researchers argue that instead of dark energy causing the universes growth, it could be explainedby constant quantum fluctuations of vacuum energy.

In their work, the researchers argue that, instead of dark energy causing the universes growth, it could be explainedby constant quantum fluctuations of vacuum energy. The paper claims if their findings are true that the old cosmological constant problem would be resolved. The press release notes the potentially transformative nature of the work: Their calculations provide a completely different physical picture of the universe.

Similarly, Bill Unruh, the physics and astronomy professor who supervised P.H.D student Qingdi Wangs work,stated thatthe research offers an entirely new take on old problems: This is a new idea in a field where there hasnt been a lot of new ideas that try to address this issue. In the end, their calculations provide a fundamentally different picture of the universe: one in which space-time is constantly moving, fluctuating between contraction and expansion.Its the small net effect towards expansion, though, that drives the expansion of the universe.

Unruh uses the sea as an analogy to explain why we cannot feel the effects: Its similar to the waves we see on the ocean [] They are not affected by the intense dance of the individual atoms that make up the water on which those waves ride.

Previous beliefhas held that the universe is expanding steadily due to dark energy pushing other matter further and further away. When we apply quantum theories to vacuum energy, it results in an increasing density which could in turn result in universal explosion due to the gravitational effect of the density.

The discovery that the universe is expanding was made simultaneously by two independent teams in 1998: Supernova Cosmology Project and the High-Z Supernova Search Team. Three members of the two teams have since won Nobel prizes for their work, which measured light using standard candles. Since that discovery was made, scientists have tried to work outexactly what this energy is thats driving the cosmos apart.

Despite the fact that it has been a compelling mystery for decades, there havent been that many theoriesposed. So, while the work of Wang and Unruh may not provide the ultimate answer, they present a new, potential solution to one of the most fundamental problems in cosmology.

Editors note: This article has been updated. A previous version mistakenly referred to dark energy as dark matter.

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New Research May Reconcile General Relativity and Quantum Mechanics - Futurism

By Josh Mitteldorf

How surprised should we be if 4 billion years of evolution have taught the living cell to exploit quantum mechanics in ways that human physicists have not yet discovered? Science has made great progress in the last century via reductionism, understanding the parts and building up to an understanding of the whole. The idea of a direct link between micro-world of quantum mechanics and the complexity of life could disrupt that paradigm.

From ancient times, it was obvious to people the world over that life played by different rules. Flowers and frogs could do things that rocks and babbling brooks could never do. Great scientists through Newton and Faraday saw no conflict between their spiritual beliefs and the laws of nature they were discovering. Then, in the 19th Century, organic chemistry was developed, and cells could be viewed through a microscope. Some of the behavior of living things began to find explanations in terms of physics and chemistry. One after another of the abilities of living cells were explained with the same laws that apply to non-living matter. Science and philosophy came to make a bold extrapolation: There is no fundamental difference. Living and non-living matter obey the same laws, and the apparent difference between living and non-living systems is due to complexity only.

This possibility became a presumption and then a dogma. Worse, the laws that governed life were presumed to be physics that humans have presently mastered and understood. Scientific consensus lined up against the idea that life may know something we dont know.

Of course, biology continues to hold many mysteries for us: Animal navigation and extraordinary knowing; the remarkable efficiency of evolution, and the related problem of the origin of life; why should microwaves cause cancer? why, indeed, should weak radio waves have any interaction with living tissue? How can biological enzymes be so much more specific than engineered catalysts, and why are they less effective in a petri dish than in a living cell?

In the process of attacking these open questions of biology, will we discover new physics? To date, only a handful of quantum biologists are asking such questions.

The first and most famous proponent of quantum biology was Erwin Schrdinger, a founding father of quantum physics. In the 1930s, he wrote two monographs [republished in one volume] about physics and life. The first one prefigured by more than a decade Crick and Watsons discovery of the structure of DNA. The second hypothesized that consciousness has an elemental role in the fabric of physics. Though this latter idea sounds mystical and vaguely unscientific to biologists, it is taken seriously by physicists because the postulates of quantum mechanics require* a subjective observer, and reality is not objective or observer-independent, but arises from the interaction between the observer and his representation of a physical system. A world without objective reality? This sounds too fantastical to take seriously, and most scientists dont.

Since Schrdinger, there have been reports of experimental results that would seem to support his conjectures about the quantum basis of life, but these have remained on the edge of science, subjected to a rigid skepticism because they would seem to require such a radical re-conception of the reductionist view of science. In the standard scientific picture, physics explains atoms and molecules; atomic physics is the explanation for chemistry; and chemistry explains the behavior of biological systems. The alternative is that the loop may be closed: biology is necessary to explain fundamental physics. (Theres a joke** with the punch line, God is a biologist.)

Aside from the quantum mechanical observer, another reason to take this idea seriously is a series of remarkable coincidences first noted by astrophysicists: The recipe for our universe contains six fundamental but arbitrary ratiosthings like the ratio of the electron to proton mass and the ratio of the electric force to the gravitational force. These ratios give the appearance of being fine-tuned to make life possible. If any of them were just a wee bit different, we would live in a universe that was very much less interesting than the one we do live in. (For example a universe in which the only chemical element is hydrogen, or a universe in which intergalactic gas remains spread thin and never congeals into stars and planets.)

What is the significance of the fact that these arbitrary ratios are fine-tuned to make life possible? One explanation would be that consciousness played a founding role, and is in some way responsible for the world we see. The alternative is that there are many universes, (billions and billions) and almost all of them harbor no life, because life is not possible there, so of course we find ourselves in one of the exceedingly rare universes that is capable of supporting life.

Aside from these broad, philosophical arguments, there are two direct observations opening the door to quantum biology. Photosynthesis and magnetic sensors in birds are made possible by quantum superpositions within single molecules. A more expansive view of quantum biology is that life depends on quantum tricks that allow micron-sized systems to explore many possibilities simultaneously, and enable single molecules to flip switches for entire cells. These are considered radical ideas, outside the mainstream of science, but perhaps they provide a fertile hypothesis for exploring many mysteries of biology.

Stunning reports of the quantum influence of living systems have been dismissed as not worthy of review or replication, because we know as a matter of theory that they must be mistaken. Robert Jahn, while Dean of the Princeton University School of Engineering, began an investigation of ways in which living systems (including humans) can affect quantum noise in a resistor [book]. Though his experiments were expertly and meticulously documented, they were never permitted publication in journals of physics, and in fact Dr Jahns reputation and career suffered just for having undertaken such experiments.

There is a line of experimentation from Russia reporting that plants and even bacteria are able to transmute chemical elements, a process which humans know how to do only with high-energy nuclear physics [book]. These experiments have never been replicated in the West, and the implications would be revolutionary if confirmed.

Roger Penrose, one of the most brilliant and original minds in mathematical physics, has been speculating on quantum theories of consciousness for thirty years, making specific and testable proposals. It is scandalous that his work is dismissed as crackpot by people who dont understand it. There is a mainstream view that consciousness arises from computation, and that digital computers have, in principle, everything necessary to qualify as conscious, living beings when we learn how to program them a bit better. Though this hypothesis is far from being a proven fact of science, challenging the dogma can be hazardous to a scientific career.

Stuart Kauffman is another expansive thinker who has investigated the connections between quantum mechanics, biology and consciousness. He notes that many proteins, including about half of all neurotransmitters, are in a state of quantum criticality, which means they are poised on a knife edge, easily nudged between two configurations. Why would this be true? In designing a classical machine (for example a tiny transistor, etched on a microchip), human engineers make sure that the systems performance is reliable by making it just large enough that quantum fluctuations cannot affect its behavior. There are plenty of biological systems that are also designed to be stable in this way; the DNA molecule, for example, stores information reliably over long periods of time. But natural selection seems to have gone out of her way to use neurotransmitters that are unreliable. Their behavior (and our thinking) are affected by quantum events at the smallest level. This could be a useful feature of the brain if quantum events in living systems are not random, but are guided by a larger coherence, or by consciousness as an entity, or maybe these two are different aspects of the same thing.

In 2002, a molecular geneticist from University of Surrey outlined a bold theory of quantum evolution based on extrapoloation of a well-established but paradoxical phenomenon. In the Quantum Zeno Effect, continuous observation of one quantum variable prevents a system from evolving. (Watched water never boils.) It is theoretically possible, in this way, to prevent a radioactive nucleus from decaying. The Inverse Quantum Zeno Effect is yet stranger: By very gradually changing the quantum variable under observation, it is possible to guide a quantum system efficiently from one state to another. In a simple demonstration (try this at home!), a series of rotated polarized filters can nudge vertically polarized light around until it becomes horizontally polarized, though the overlap between the initial and final wave functions is zero. In this book, Johnjoe McFadden speculated that biological evolution might be directed toward states of higher fitness by a biological version of the Inverse Zeno Effect. Fifteen years later, only a handful of scientists around the world are discussing and developing these ideas. We are so busy working out the details of our existing framework (and writing grant proposals to compete for next years funding) that we have no time to consider speculations outside the box.

Mcfadden stopped short of proposing an observer within the living cell that is driving its evolution, a deus ex machina, but connection to Penroses work presents a tantalizing possibility. Perhaps the contentious observer problem of quantum mechanics is essentially related to free will, awareness and the sense of self; perhaps the quantum observer within is what separates living from non-living things, and is the source of the characteristic behaviors that strike us as goal-oriented.

These intriguing ideas touch our foundational sense of who we are and the nature of the world in which we live, but the enterprise of science today is not well adapted to address them. Funding is risk-aversea sound basis for business decisions, but a disaster for the healthy practice of basic science. Hypotheses about quantum biology are easily dismissed as crackpot, and indeed most are likely not to pan out. But you have to kiss many a frog before you find your prince. If we are ever to address these foundational questions, wethe community of scientistswill have to be willing to consider and to test a great number of crazy ideas along the way.

We know the quantum world primarily from single-particle systems. All of atomic physics, chemical bonds, orbitals etc. is modeled from equations of the hydrogen atom, because for more than one electron, quantum mechanical equations are impossible to solve. Quantum physics of many entangled particle is notoriously intractable to computation, so we have only semi-empirical theories of chemistry and solid state physics. With quantum symmetries, we can explain simple, uniform orderfor example, lasers and crystals. But theory suggests the possibility of a single quantum state that comprises many atoms in a complex array; indeed, a system may be in a superposition of several such states simultaneously. We know nothing of such systems, or what properties they might evince; that is, we know how to write down the equations for such systems but to solve the equations is far beyond the capability of any computer we know how to build. Quantum mechanics of complex systems remains an experimental science, and evolution has had time to perform a great many more experiments than have humans.

* There is an alternative formulation of quantum mechanics where observers are not outside of quantum physics, but this formulation carries the baggage of a truly gigantuous number of extra universes, all them completely unobservable. It is called the Many Worlds Interpretation.

** Escalating reductionism: Biologists think theyre chemists, chemists think theyre physicists, physicists think theyre mathematicians. Of course, mathematicians think theyre God, but what they dont realize is that God is a biologist.

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Quantum Biology and the Frog Prince - ScienceBlog.com (blog)

Physicists have been trying to unite the discipline's dominant theories of quantum mechanics and general relativity into a grand unifying theory for years and a group of University of British Columbia researchers think they might finally have made some progress towards a solution.

The theories of quantum mechanics and general relativity are the two best ways we have to describe how the universe works.

Quantum mechanics is a branch of physicsthat examines the natural world at the sub-atomic level.

Einstein's theory of general relativity explains phenomena on a grander scale like black holesor how light travels through a galaxy.

While each theory works well to describe phenomena in its respective area, they are mutually incompatible, according to JaymieMatthews, a professor of astronomy and astrophysics at the University of British Columbia..

Even famed Cambridge University mathematics professor Stephen W. Hawking switches between the theories of quantum mechanics and general relativity, Matthews says. (Kimberly White/Reuters)

"General relativity has passed every test that has been put to it. Quantum mechanics as a theory has passed every test that has been applied to it," explained Matthews.

"But if you try to take general relativity to the tiniest scales, it kind of breaks down, and if you take quantum mechanics to the largest scale, it breaks down."

The solution has been to use the theories in their respective areas and kind of avoid the "elephant in the universe" incompatibility issue.

"That profound disagreement between general relativity and quantum mechanics disturbs people."

A new paper by three UBC scientists attempts to reconcile these two theories by addressing the problem of our expanding universe.

Astronomers say theuniverse is constantly expanding at an ever-increasing rate which suggests something, which scientists refer to as dark energy,is pushing it out.

When physicists apply quantum mechanics to this problem, they theorize the energyin questionmust be incredibly dense.

But the theory of relativity says energy with this much density would have a strong gravitational effect which some scientists maintain would cause the universe to explode, which, of course, hasn't happened.

In their paper, UBC PhD students Qingdi Wang and Zhen Zhu, along with physics and astronomy professor Bill Unruh, have devised a formula where they say the value of this forceis fluctuating wildly between positive and negative values and the net result is almost zero.

This accounts for both the zero density and the ever-increasing expansion.

The paper says we can't feel the movement because it is very, very small.

"This happens at very tiny scales, billions and billions times smaller even than an electron," described Wang in a news release.

The research is important because if it is well-received, it could put us closer to a uniform theory of everything.

"If quantum mechanics and general relativity can agree with one another, there is no disturbing cosmological elephant in the universe. That would remove one of the most frustrating things," Matthews said.

Listen to the interview withJaymie Matthews on CBC's The Early Edition:

"We like to think we live in an elegant universe," he added. "This would be one step closer to a grand unified theory in which you could describe the universe on a piece of paper."

The research paper was published in Physical Review D last week.

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UBC researchers propose answer to fundamental space problem - CBC.ca

May 12, 2017 Eduardo Mucciolo, Professor and Chair of the Department of Physics at the University of Central Florida. Credit: University of Central Florida

A well-known computational problem seeks to find the most efficient route for a traveling salesman to visit clients in a number of cities. Seemingly simple, it's actually surprisingly complex and much studied, with implications in fields as wide-ranging as manufacturing and air-traffic control.

Researchers from the University of Central Florida and Boston University have developed a novel approach to solve such difficult computational problems more quickly. As reported May 12 in Nature Communications, they've discovered a way of applying statistical mechanics, a branch of physics, to create more efficient algorithms that can run on traditional computers or a new type of quantum computational machine, said Professor Eduardo Mucciolo, chair of the Department of Physics in UCF's College of Sciences.

Statistical mechanics was developed to study solids, gasses and liquids at macroscopic scales, but is now used to describe a variety of complex states of matter, from magnetism to superconductivity. Methods derived from statistical mechanics have also been applied to understand traffic patterns, the behavior of networks of neurons, sand avalanches and stock market fluctuations.

There already are successful algorithms based on statistical mechanics that are used to solve computational problems. Such algorithms map problems onto a model of binary variables on the nodes of a graph, and the solution is encoded on the configuration of the model with the lowest energy. By building the model into hardware or a computer simulation, researchers can cool the system until it reaches its lowest energy, revealing the solution.

"The problem with this approach is that often one needs to get through phase transitions similar to those found when going from a liquid to a glass phase, where many competing configurations with low energy exist," Mucciolo said. "Such phase transitions slow down the cooling process to a crawl, rendering the method useless."

Mucciolo and fellow physicists Claudio Chamon and Andrei Ruckenstein of BU overcame this hurdle by mapping the original computational problem onto an elegant statistical model without phase transitions, which they called the vertex model. The model is defined on a two-dimensional lattice and each vertex corresponds to a reversible logic gate connected to four neighbors. Input and output data sit at the boundaries of the lattice. The use of reversible logic gates and the regularity of the lattice were crucial ingredients in avoiding the phase-transition snag, Mucciolo said.

"Our method basically runs things in reverse so we can solve these very hard problems," Mucciolo said. "We assign to each of these logic gates an energy. We configured it in such a way that every time these logic gates are satisfied, the energy is very low - therefore, when everything is satisfied, the overall energy of the system should be very low."

Chamon, a professor of physics at BU and the team leader, said the research represents a new way of thinking about the problem.

"This model exhibits no bulk thermodynamic-phase transition, so one of the obstructions for reaching solutions present in previous models was eliminated," he said.

The vertex model may help solve complex problems in machine learning, circuit optimization, and other major computational challenges. The researchers are also exploring whether the model can be applied to the factoring of semi-primes, numbers that are the product of two prime numbers. The difficulty of performing this operation with very large semi-primes underlies modern cryptography and has offered a key rationale for the creation of large-scale quantum computers.

Moreover, the model can be generalized to add another path toward the solution of complex classical computational problems by taking advantage of quantum mechanical parallelismthe fact that, according to quantum mechanics, a system can be in many classical states at the same time.

"Our paper also presents a natural framework for programming special-purpose computational devices, such as D-Wave Systems machines, that use quantum mechanics to speed up the time to solution of classical computational problems," said Ruckenstein.

Zhi-Cheng Yang, a graduate student in physics at BU, is also a co-author on the paper. The universities have applied for a patent on aspects of the vertex model.

Explore further: Study offers new theoretical approach to describing non-equilibrium phase transitions

More information: C. Chamon et al, Quantum vertex model for reversible classical computing, Nature Communications (2017). DOI: 10.1038/ncomms15303

Imaginary numbers are a solution to a very real problem in a study published today in Scientific Reports.

While technologies that currently run on classical computers, such as Watson, can help find patterns and insights buried in vast amounts of existing data, quantum computers will deliver solutions to important problems where ...

One of the most striking discoveries of quantum information theory is the existence of problems that can be solved in a more efficient way with quantum resources than with any known classical algorithm.

How fast will a quantum computer be able to calculate? While fully functional versions of these long-sought technological marvels have yet to be built, one theorist at the National Institute of Standards and Technology (NIST) ...

(Phys.org) -- While there has been some skepticism as to whether the Canadian company D-Waves quantum computing system, the D-Wave One, truly involves quantum computing, the company is intent on proving that the system ...

Physicists have developed a quantum machine learning algorithm that can handle infinite dimensionsthat is, it works with continuous variables (which have an infinite number of possible values on a closed interval) instead ...

A well-known computational problem seeks to find the most efficient route for a traveling salesman to visit clients in a number of cities. Seemingly simple, it's actually surprisingly complex and much studied, with implications ...

By precisely measuring the entropy of a cerium copper gold alloy with baffling electronic properties cooled to nearly absolute zero, physicists in Germany and the United States have gleaned new evidence about the possible ...

When Northwestern Engineering's Erik Luijten met Zbigniew Rozynek, they immediately became united by a mystery.

It's a material world, and an extremely versatile one at that, considering its most basic building blocksatomscan be connected together to form different structures that retain the same composition.

Researchers at the National Institute of Standards and Technology (NIST) have produced and precisely measured a spectrum of X-rays using a new, state-of-the-art machine. The instrument they used to measure the X-rays took ...

Scientists have discovered a way to solve a problem that has baffled humans for so long it is mentioned in the Bible: achieving the most efficient packing of objects such as grains and pharmaceutical drugs.

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If this tech solves the traveling salesman problem in non-polynomial time without quantum computers, the Nobel Committee should create a Computer Science prize for it.

Stimulate-annealing problem was a bitch due to phase transition. This seems like actually innovation, rather than the descriptive and iceberg-meting garbage permeating the site.

Really cool work, love to see physicists in CS. Simulated Annealling is the beginning, I think there's a lot more: a principle of least information in AI will emerge, I predict, matching physics principle of least action, and in time computation will illuminate more physics. For instance, imagine if its NOT the case that there is physical solution to Travelling salesman or other NP complete problems, (meaning no physical system computes their solution) that's profound as a solution. It implies an anonymity to photons for instance, the fact that they have no history. It also lends a lot of credence to those weird ideas that we're all living in a computer simulation.

Einsteins quote about everything being explained as simply as possible is sort of similar - less energy expenditure.

Right, Occam's razor has formal statements in information theory too. Its really just kind of common sense: if we encoded the world around us smartly, common things, like an orange in an orange tree, would little information to encode, but uncommon things, like a traffic cone in an orange tree would take more info. So an AI, on seeing something orange between the leaves of an orange tree, should assume its an orange, as our brains would.

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Physics may bring faster solutions for tough computational problems - Phys.Org

In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction. The fundamental notion that a physical property may be "quantized" is referred to as "the hypothesis of quantization".[1] This means that the magnitude of the physical property can take on only certain discrete values.

For example, a photon is a single quantum of light (or of any other form of electromagnetic radiation), and can be referred to as a "light quantum". Similarly, the energy of an electron bound within an atom is also quantized, and thus can only exist in certain discrete values. The fact that electrons can only exist at discrete energy levels in an atom causes atoms to be stable, and hence matter in general is stable.

Quantization is one of the foundations of the much broader physics of quantum mechanics. Quantization of the energy and its influence on how energy and matter interact (quantum electrodynamics) is part of the fundamental framework for understanding and describing nature.

The word quantum comes from the Latin quantus, meaning "how great". "Quanta", short for "quanta of electricity" (electrons), was used in a 1902 article on the photoelectric effect by Philipp Lenard, who credited Hermann von Helmholtz for using the word in the area of electricity. However, the word quantum in general was well known before 1900.[2] It was often used by physicians, such as in the term quantum satis. Both Helmholtz and Julius von Mayer were physicians as well as physicists. Helmholtz used quantum with reference to heat in his article[3] on Mayer's work, and the word quantum can be found in the formulation of the first law of thermodynamics by Mayer in his letter[4] dated July 24, 1841. Max Planck used quanta to mean "quanta of matter and electricity",[5] gas, and heat.[6] In 1905, in response to Planck's work and the experimental work of Lenard (who explained his results by using the term quanta of electricity), Albert Einstein suggested that radiation existed in spatially localized packets which he called "quanta of light" ("Lichtquanta").[7]

The concept of quantization of radiation was discovered in 1900 by Max Planck, who had been trying to understand the emission of radiation from heated objects, known as black-body radiation. By assuming that energy can only be absorbed or released in tiny, differential, discrete packets he called "bundles" or "energy elements",[8] Planck accounted for certain objects changing colour when heated.[9] On December 14, 1900, Planck reported his findings to the German Physical Society, and introduced the idea of quantization for the first time as a part of his research on black-body radiation.[10] As a result of his experiments, Planck deduced the numerical value of h, known as the Planck constant, and could also report a more precise value for the AvogadroLoschmidt number, the number of real molecules in a mole and the unit of electrical charge, to the German Physical Society. After his theory was validated, Planck was awarded the Nobel Prize in Physics in 1918 for his discovery.

While quantization was first discovered in electromagnetic radiation, it describes a fundamental aspect of energy not just restricted to photons.[11] In the attempt to bring experiment into agreement with theory, Max Planck postulated that electromagnetic energy is absorbed or emitted in discrete packets, or quanta.[12]

The adjective "quantum" is frequently used in common parlance to mean the opposite of its scientific definition. A "quantum leap" has been used colloquially since the 1950s to imply a large change, as opposed to the smallest possible change.[13][14] It is also used in a range of pseudoscientific beliefs (quantum mysticism), where the adjective is used to imply that a paranormal event is a consequence of quantum physics.[15][16]

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Quantum - Wikipedia

May 10, 2017 The rotating centrifuge in which the entangled photon source was accelerated to 30 times its weight. Credit: IQOQI/AW

Einstein's "spooky action at a distance" persists even at high accelerations, researchers of the Austrian Academy of Sciences and the University of Vienna were able to show in a new experiment. A source of entangled photon pairs was exposed to massive stress: The photons' entanglement survived the drop in a fall tower as well as 30 times the Earth's gravitational acceleration in a centrifuge. This was reported in the most recent issue of Nature Communications. The experiment helps deepen our understanding of quantum mechanics and at the same time gives valuable results for quantum experiments in space.

Einstein's theory of relativity and the theory of quantum mechanics are two important pillars of modern physics. On the way of achieving a "Theory of Everything," these two theories have to be unified. This has not been achieved as of today, since phenomena of both theories can hardly be observed simultaneously. A typical example of a quantum mechanical phenomenon is entanglement: This means that the measurement of one of a pair of light particles, so-called photons, defines the state of the other particle immediately, regardless of their separation. High accelerations on the other hand can best be described by the theory of relativity. Now for the first time, quantum technologies enable us to observe these phenomena at once: The stability of quantum mechanical entanglement of photon pairs can be tested while the photons undergo relativistically relevant acceleration.

Quantum entanglement proves to be highly robust

Researchers of the Viennese Institute of Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences (OeAW) and of the University of Vienna have now investigated this area of research experimentally for the first time. They could show in their experiment that entanglement between photons survives even when the source of entangled photon pairs including the detectors are experiencing free fall or are being accelerated with 30g, that is, 30 times the Earth's acceleration. Doing so, the Viennese researchers have experimentally established an upper bound below which there is no degradation of entanglement quality.

Important for quantum experiments with satellites

"These experiments shall help to unify the theories of quantum mechanics and relativity," says Rupert Ursin, group leader at IQOQI Vienna. The sturdiness of quantum entanglement even for strongly accelerated systems is crucial also for quantum experiments in space. "If entanglement were too fragile, quantum experiments could not be carried out on a satellite or an accelerated spacecraft or only in a very limited range," exemplifies Matthias Fink, first author of the publication.

12 meters falling height and 30g

In order to prove the robustness of quantum entanglement, quantum physicist Matthias Fink and his colleagues mounted a source of polarization-entangled photon pairs in a crate which was firstly dropped from a height of 12 meters to achieve zero gravity during the fall. In the second part of the experiment, the crate was fixed to the arm of a centrifuge and then accelerated up to 30g. As a comparison for the reader: A roller coaster ride exerts maximally 6g on the passengers.

Detectors mounted on the crate monitored the photons' entanglement during the experiments. Analysing the data, the physicists could calculate an upper bound of disadvantageous effects of acceleration on entanglement. The data showed that entanglement quality did not significantly exceed the expected contribution of background noise. "Our next challenge will be to stabilize the setup even more in order for it to withstand much higher accelerations. This would enhance the explanatory power of the experiment even further," says Matthias Fink.

Explore further: Researchers demonstrated violation of Bell's inequality on frequency-bin entangled photon pairs

More information: Experimental test of photonic entanglement in accelerated reference frames, Nature Communications, 2017. DOI: 10.1038/NCOMMS15304

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It's way past time for sci-writers to stop gushing, "Spooky action, blah, blah". No one not living on Mars is not sick of this tired put-down of entanglement, not unlike the despised `god particle' moniker of the Higgs. AE did not believe in god or spooks, & used those terms colloquially. But now the sci-writers, lacking any creativity for modern descriptions, all parrot AE.

What? Is this supposed to mean the centrifuge produced 30g?

The use of intriguing and interesting language to inspire interest in the subject at hand is a tool used by all journalists. Spooky action at a distance has been referred to as often as it has because it is effective at gaining attention. To lobby for the removal of such an iconic phrase as spooky action at a distance from scientific journals would be counterproductive to the goal of spreading interest in the scientific study of reality and the laws governing it. There is an intrinsic value to use outrageous language to describe outrageous scientific phenomenon. One of Einstein's greatest contributions to science was the interest he created in the subject. Also while his religious beliefs were far from firmly established he often referred to a Force having a role in the guiding of our universe. The article was informative, interesting, and entertaining. And just to make clear what was very clear in the article, yes 30 times Earth's gravity is 30g. It said 30g multiple times

The force does not guide. It survives. Whether anyone learns... we'll see.

Fill a bucket on a rope with water, whirl it around, figure out why the water doesn't spill. Or read this 🙂 https://en.wikipe...ntrifuge

What was discovered was that the aperatus could survive. The limited "relative forces" of these experiments really can't be expected to do much else. Want to determin the "strength" of entangment then send one of the entangled pairs through an accelerator.

Hence you have here peddling cliches, catch phrases, gross simplifications in the aura of mystery and discovery while scientific formalism suffers. All in attempt to draw audiences to science and advertisers.

This particular piece fails to explain what actually those researchers wanted to accomplish and why would they expect entanglement of photons (a phase entanglement vs. spin (magnetic) entanglement) to be affected by inertial acceleration of measly 30g (1E5g may be).

Also and most importantly why would they expect to influence an "undetermined" state of a phase of light of entangled pair by mechanical force. I am sure in the paper they answer those questions quite simply.

An interesting take on addressing the problem of misinterpretation of QM I found here: https://questforn...-quanta/

It's an important point that entanglement still occurs across varying gravity strengths. It's one of those assumptions that must be tested; these are some important negative results.

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FORT WORTH (CBS11) He studies the theories behind the subatomic building blocks of the universe. Hes earned a degree in physics from TCU. He is 14-years old.

Most 14-year-olds are learning to navigate the halls of high school as a freshman.

Carson Huey-You navigates the intricate world of quantum physics on a wall-sized college classroom white board.

Im studying physics but in particular quantum physics eventually going into research and teaching after graduate school, he said.

Huey-You will graduate TCU with a bachelors degree in physics Saturday.

He was 10 when Professor Magnus Rittby took him under his wing.

Of course I had reservations, he laughed. Ive never seen a 10-year-old apply for college. But he was a bright kid and I just thought it was worth fighting for him to get admitted and try it.

The age difference between him and his classmates is something Huey-You is accustomed to. After homeschooling, he started school in the 8th grade at five years old.

Its no different than what Im used to because I was around it all through high school, Huey-You said. So, I got used to it there and its really the same thing here. Its also good because they sort of accept me as an equal.

And that acceptance came with more than classwork as a 10-year-old had to learn how to manage himself maturely in a college environment.

I tried making it work both ways, Rittby said. That is, being mature about the academics but still being able to be a kid at heart which I think he still is. And I want to keep it that way.

I have Cannan my younger brother, Huey-You said of how he spends his down time. So we play together a lot. I have a puppy named Klaus. He likes to run around and hes very energetic.

Perhaps its not surprising that in a world of theoretical formulas where age is not a factor Huey-You never thought that he could actually earn his PhD when other students his age are graduating high school.

Its kind of surprising but then at the same time its really cool! he laughed.

His younger brother Cannan is graduating high school this week and will study physics and astronomy at TCU.

He is 11 years-old and already has taken some advanced classes at TCU.

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14-Year-Old Earns Physics Degree From TCU CBS Dallas / Fort ... - CBS DFW

Quantum entanglement is just one of the many weird things that pop up when you try to understand the laws governing the world of subatomic particles. The phenomenon of entanglement wherein two particles can be separated by billions of light-years and yet be instantly affected by changes to the quantum state of one another seems so outlandish that even Albert Einstein (the essence of intelligence anthropomorphized) had trouble wrapping his head around the concept.

Despite Einsteins reservations, though, quantum entanglement has been empirically observed several times over the past few decades. The spooky action at a distance as the famed physicist once derisively called it is very real.

Read:Schrdingers Cat Is Now Dead And Alive In Two Boxes

In a series of experiments described in a study published Wednesday in the journal Nature Communications a team of researchers has now shown that quantum entanglement persists even at high accelerations. The experiments not only help scientists deepen their understanding of quantum mechanics, they also help them take a step toward the holy grail of particle physics the unification of quantum mechanics and relativity.

In their experiments, the researchers subjected pairs of entangled photons to accelerations of up to 30g (or 30 times the acceleration due to gravity a free-falling object experiences on Earth) in centrifuges.

Detectors mounted on the crate monitored the photons' entanglement during the experiments. Analysing the data, the physicists could calculate an upper bound of disadvantageous effects of acceleration on entanglement, the University of Vienna explained in a statement. The data showed thatentanglement quality did not significantly exceed the expected contribution of background noise.

Not only do the experiments prove that the phenomenon of entanglement is strong enough to persist even in experiments that may one day be carried out on a satellite or an accelerated spacecraft, they also suggests quantum mechanical entanglement ofphoton pairscan be tested while the particles undergo relativistic acceleration conditions under whichattempts to unify quantum mechanics and relativity into an overarching theory of everything can be made.

Currently, the universe we live in obeys two seemingly incompatiblelaws quantum mechanics, whichgovernsthe behavior of subatomic particles;and relativity, which describeshow clumps of atoms, such ashumans, stars and galaxies,behave. Formulating an all-encompassing theory of everything, one that resolves the apparent contradictions between quantum mechanics and relativity has, for the longest time, been the main goal of particle physicists.

This, however, is easier said than done. The seemingly insurmountable problem is that gravity, which is a product of massive objects warping space-time as explained by Einsteins theory of general relativity does not follow the laws of quantum physics.

As long as these descriptions of nature remain confined to their own scope of application, they cannot contribute to a unified theory that captures physics at the boundary between these specialized regimes, the researchers wrote in the study. Our experimental platform represents a testbed that can readily be upgraded for measurements with higher precision, by using a ultra-bright source of entangled photons, and higher-dimensional degrees of freedom, such as energy-time entanglement.

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