Category Archives: Quantum Physics

One of the most compelling ideas in all of physics sounds like pure fiction, but it could actually describe our reality: the idea of a multiverse. In the multiverse scenario, what we know as our universe is just one of many universes that independently and simultaneously exist in parallel to our own. Although there is no compelling evidence that points toward either the existence or nonexistence of the multiverse, it provides us with a rich area for exploration, because the predictions of its existence are firmly rooted in theoretical physics phenomena that are definitively known to exist.

If we presume that:

Then it follows that the existence of a multiverse is all but inevitable. It opens up a rich realm of physical possibilities that include not only parallel universes, but also an infinite number of them out there. If thats the case, there could even be parallel universes identical to our own, where reality forks each time a quantum outcome occurs. Heres whats possible within a scientific consideration of the multiverse.

To understand why physicists assert that a multiverse ought to exist, you first have to understand a few facts about the universe that we observe. One fact is that we have a boundary to the part of the universe that we can access: a boundary in time. The universe as we can see it began some ~13.8 billion years ago in an event known as the hot Big Bang, where the universe was hot, dense, filled with matter and radiation, and was expanding, cooling, and gravitating from that initial state. The farther we look back in space, the farther we wind up looking back in time, all the way to the boundary of the hot Big Bang: 13.8 billion years ago in time and 46.1 billion light-years away in space.

However, you cant go back to arbitrarily early times, because if the universe had exceeded a certain temperature and density, it would have properties we specifically observe it not to have. Instead, observations are far more consistent with the notion that the hot Big Bang was preceded and set up by a period of cosmic inflation, which:

When inflation comes to an end, we get a hot Big Bang with the necessary properties to reproduce the observable universe.

Typically, we like to visualize inflation as a simple field: it has certain properties that affect the space over which the field is present. As long as the field remains in this inflationary state, where the fabric of space has a large energy inherent to it, space will expand relentlessly and exponentially, so that the distance between any two points successively doubles with each passing interval of time.

As long as the field remains in this inflationary state, inflation continues, stretching the fabric of space, diluting everything in it until the field decays. At that moment, inflation ends. As the energy gets converted into matter and radiation, the universe heats up to a very high (but not arbitrarily high) temperature, signifying the beginning of the hot Big Bang.

In actuality, however, we know that whatever field drives inflation is overwhelmingly likely to be quantum in nature. That means, as inflation goes on, theres a certain probability that the field will: roll into the valley where inflation ends; a certain probability that it wont and inflation will continue; and even a certain probability that the field will roll in the wrong direction, taking us farther away from inflations end. And heres the counterintuitive part because the inflating universe continuously creates new space, all of these possibilities can occur simultaneously in different regions of the inflating universe.

This sets up a fascinating scenario to consider. As long as inflation occurred in the past, which we have copious evidence that it did based on whats imprinted in our universe, it implies the existence of a multiverse. Whats going on is the following:

And so on.

Fascinatingly, its fairly easy to show that if you want to create a scenario where we get enough inflation to set up the hot Big Bang with the properties we observe, you will always get a multiverse one where independent, disconnected universes are always being born, forever separated from one another by space that continues to inflate eternally, while new universes and new hot Big Bangs continue to spawn. As long as weve got this part of the story correct and the evidence overwhelmingly indicates that we have the existence of a multiverse is predicted by todays best science.

Now, this is where we have to enter into speculative territory. We know that inflation must occur at an energy scale thats significantly below the Planck energy scale, otherwise we would see signals in our universe that dont exist. What we dont know, however, is supremely important. We dont know how inflation began, or whether it even had a beginning; its possible that inflation was the default state of the universe that was happening eternally, until it ended in our region of space and our universe was spawned.

We dont know whether there are any entangled properties between these different universes within the multiverse. We dont know whether all of the universes that are spawned have the same physical laws and fundamental constants, or whether there are dynamics that govern these laws and constants that somehow get set either during inflation or the final transition to the hot Big Bang. Additionally, we have no idea how to quantify the probabilities of these different outcomes: what cosmologists working on it call the measure problem. These universes are predicted to exist, but we dont know how many of them there are, whether or how theyre related, and what similarities or differences they have relative to our own universe.

However, the expectation based on what we can measure within our own universe and what we can calculate based on the quantum properties that the known particles and fields possess is that the laws and constants should be the same between universes, but the specific initial conditions should be different.

What does this mean?

It means that the overall properties of each universe should be the same, because they had a common origin: from the end of the same inflationary field. That means each universe should be born with the same average energy density, the same laws, the same symmetries, the same conserved quantities and conservation laws, the same Standard Model, the same rules of general relativity, and many other properties. The big differences, simply, should come in the form of quantum fluctuations that get superimposed atop this uniform background: the 1-part-in-30,000 imperfections that provided the seeds of cosmic structure in our universe. These should be random and on all scales, and our universe should be just one of an extraordinarily large set of possible outcomes.

And yet, if you have enough of these universes that spring into existence, there should eventually be one that comes along with the exact same initial properties as our own. Remember that everything that exists in our universe is finite: there are a finite number of particles, a finite amount of energy, a finite amount of time over which interactions between quanta can occur, and a finite number of possible outcomes. These numbers are astronomically large, but they are not infinite.

It may or may not be the same story when it comes to the number of universes that are spawned by inflation. If inflation has proceeded for a finite amount of time, then the number of universes we get increases exponentially with time, but always remains finite. If inflation has gone on for an infinite amount of time, then the number of universes must be infinite, and all allowable possibilities must have occurred in some universe.

If inflation has gone on for only a finite amount of time, we can strongly say that, based on how the number of universes increases with time versus how the number of possible outcomes within a single universe increases with time, there are no parallel universes equivalent to our own within the multiverse. When we talk about the many-worlds interpretation of quantum mechanics, a finite number of universes is insufficient to hold all of the possible outcomes. We require an infinity of worlds. This itself requires an infinite duration to inflation to make a parallel universe identical to our own a possibility.

But if inflation has gone on for an infinite amount of time, then the existence of identical parallel universes isnt just possible, but mandatory. No matter how large a finite number gets, even if it tends towards infinity over time, it will never become infinite after a finite amount of time.

Therefore, even though there are an astronomical number of possible outcomes that could have occurred including quantum interactions with a continuous set of allowable outcomes an infinite number of parallel universes must contain them all.

However, even if such parallel universes do exist within a larger multiverse, even if there are an infinite number of them, not every imaginable effect is possible. You cannot transfer anything between universes, for example. Even though every universe emerged from the same small region of space seeing as you can trace any two points back in an inflating spacetime until theyre arbitrarily close together no information can ever be transferred between them; they are no longer causally connected.

There is no retrocausality that occurs. In other words, what happens in one universe cannot affect another. We know how to quantify what would occur, during inflation, if any two universes collided, merged, or otherwise interacted, and we can definitively state that there is no such evidence of that having occurred in our universe.

Additionally, the quantum possibilities that now exist for our universe are only possible for future events whose outcomes have already been determined. The idea that multiple histories could overlap to create the reality we now inhabit often colloquially known as the Mandela effect is a physically inadmissible example of pseudoscience, unsupported by any evidence at all.

Its extraordinarily tempting to consider the possibility that all of our mistakes and bad decisions, and the consequences that have ensued for ourselves and others because of them, might have turned out differently elsewhere. At another time in another place, perhaps there was a version of you that made better decisions at a critical juncture, and that version of you, in another universe, is having a better life and inhabiting a better world because of it. The idea of the multiverse, and specifically of parallel universes that were identical to our own until those critical decisions, offers us the hope that our past decisions are not as immutable as we currently believe.

And yet, thats not at all what the science indicates. Even if inflation has been ongoing for an infinite amount of time, whatever occurs in the other universes that exist are in no way related to what is occurring or has occurred in our universe. Our past is fundamentally written. There are no opportunities arising in any multiverse scenario either to rewrite the past or to import, from another universe, an outcome that turned out differently. The multiverse may be inevitable and parallel universes may be possible, but they do not affect our universe is any measurable or observable way. Beyond the limits of science, all we have is speculation. Until the evidence catches up, no further definitive statements can be made.

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Could the multiverse have parallel universes identical to ours? - Big Think

Our quirky minds thwart psychologists efforts to find durable theories. But terror-management theory has held up quite well since three psychologists proposed it more than 30 years ago. It holds that fear of death underpins many of our actions and convictions. We cling to our beliefs more tightly when reminded of our mortality, especially if those beliefs connect us to something transcending our puny mortal selves.

Terror-management theory can account for puzzling political trends, such as our attraction to outlandish conspiracies and authoritarian leaders. Last year I invoked the theory to explain why Donald Trumps popularity surged at the beginning of the COVID-19 pandemic. Recently I have begun to wonder whether terror-management theory can explain trends in physics, too.

Physicists pride themselves on their rationality, yet they are as prone to existential dread as the rest of us, if not more so. Their investigations force them to confront infinity and eternity in their day jobs, not just in the dead of night. Moreover, physicists equations describe particles pushed and pulled by impersonal forces. There is no place for love, friendship, beauty, justicethe things that make life worth living. From this chilly perspective, the entirety of human existence, let alone an individual life, can seem terrifyingly ephemeral and pointless.

Steven Weinberg, arguably the greatest physicist of the last half-century, urged us to accept the soul-crushing implications of physics, and he rejected attempts to turn it into a substitute for religion. In Dreams of a Final Theory, Weinberg said science cannot replace the consolations that have been offered by religion in facing death. Weinberg, who died in July, was unusually resistant to wishful thinking (except for his thinking about a final theory). Other physicists, I suspect, cling to certain hypotheses precisely because they make mortality more bearable. Below are examples.

There is a whole class of conjectures that, like religion, give us a privileged position in the cosmic scheme of things. Call them we-were-meant-to-be-here theories. They imply that we are not an accidental, incidental part of nature; our existence is somehow necessary. Without us, the universe might not exist. One example is the anthropic principle, which dates back to the 1960s. The anthropic principle suggests that the laws of nature must take the form that we observe because otherwise we would not be here to observe them.

The anthropic principle is a tautology masquerading as a truth, but it has proved remarkably resilient. Stephen Hawking took it seriously, as did Weinberg. A major reason for the endurance of the anthropic principle is the proliferation of multiverse theories, which hold that our universe is just one of many. If you buy multiverses (to which I will return below), the anthropic principle can help explain why we find ourselves in this particular universe with these particular laws.

Quantum mechanics has inspired lots of we-were-meant-to-be-here proposals because it suggests that what we observe depends on how we observe it. Look at an electron this way, it behaves like a particle; that way, it resembles a wave. Physicists, notably Eugene Wigner and John Wheeler, have speculated that consciousness, far from being a mere epiphenomenon of matter, is an essential component of reality. Your individual consciousness might not endure, but consciousness of some kind will last for as long as the universe does. I critique these we-were-meant-to-be-here propositions here and here.

A more subtle source of consolation is what Richard Feynman, in The Character of Physical Law, calls the great conservation principles. According to these laws, certain features of nature remain constant, no matter how much nature changes. The best-known conservation law involves energy. Energy can take many formskinetic, potential, electrical, thermal, gravitational, nuclearand it can change from one form into another. Matter can become energy, and vice versa, as Einstein revealed with his famous equation E = mc2. But if you add up all the kinds of energy at any given instant, that sum remains constant.

Other conservation laws apply to angular momentum and charge. In what way are these laws consoling? Because to be human is to know loss. When we look at the worldand at our own faces in the mirrorwe see the terrible transience of things. What we love will vanish sooner or later. It is reassuring to know that, on some level, things stay the same. According to conservation laws, there are no endings or beginnings, only transformations.

The most consoling conservation law involves information. Physicist Leonard Susskind says conservation of information underpins everything, including classical physics, thermodynamics, quantum mechanics, energy conservation, that physicists have believed for hundreds of years. According to the law, everything that happens leaves its imprint, permanently, on the universe. Eons after you die, after the earth and the sun have vanished, every minute detail of your life will endure in some formsupposedly.

Back to multiverse theories, which stipulate that our universe is just one among multitudes. Physicists have proposed different multiverse theories inspired by quantum mechanics, string theory and inflation, a speculative theory of cosmic creation. What the theories all have in common is a lack of evidenceor even the hope of evidence. So what explains their popularity?

Here is my guess: physicists are freaked out by the mortality of our little universe. What was born must die, and according to the big bang theory, our cosmos was born 14 billion years ago, and it will die at some unspecified time in the far future. The multiverse, like God, is eternal. It had no beginning; it will have no end. If you find that proposition reassuring, perhaps you shouldnt read this critique of multiverse theories.

Determinism, physics-style, assumes that reality is strictly physical. Everything that happens, including our choices, results from physical forces, like gravity pushing and pulling physical objects. Moreover every present moment is associated with a single unique past and a single unique future. I do not like determinism because it subverts free will and makes us more likely to accept that the way things are is the way they must be.

But I can see the upside of determinism. The world often seems disturbingly out of control. We have the sense that at any moment bad things might happen, on scales small and large. A truck might strike you as you cross the street, absent-mindedly brooding over quantum mechanics. A nearby supernova might bathe the earth in lethal radiation. Millions of my fellow citizens might become enthralled by a thuggish buffoon. A mutant virus might suddenly emerge from who knows where and kill millions of people.

We desperately want to believe that beneath the apparent randomness, someone or something is in control. God, for many people, is the tough but fair chief executive running this seemingly chaotic cosmic corporation. It is hard for us to see Her/His/Their plan, but She/He/They surely know what She/He/They are doing.

If you find the God hypothesis implausible, then perhaps an extreme form of determinism, called superdeterminism, might serve as a substitute. Superdeterminism attempts to eliminate several puzzling features of quantum mechanics, including the apparent randomness of quantum events and intrusive role of measurement. Two physicists I admire, Sabine Hossenfelder and Gerard t Hooft, have promoted the theory.

According to superdeterminism, the universe is not careening wildly into an unknowable future. It is gliding serenely, undeviatingly, along a rigid track laid down at the beginning of time. As a free-will fanatic I do not find this perspective comforting, but I understand why others do. If determinism is true, there is nothing you can do to change things, so sit back and enjoy the ride. Everything is as it should beor must be.

The one physics principle that is hard to spin positively is the second law of thermodynamics. It decrees that all the creative energy in the universe will eventually dissipate, becoming useless heat. The marvelous, intricate structures that we see around usstars, planets, cathedrals, oaks, dragonflies, human beingswill vanish. The universe will descend into heat death, a state in which nothing ever happens. Clever physicists have imagined ways in which we can escape this dismal fate, but their proposals do not seem much more plausible than the heaven hypothesis.

I dont find any physics hypotheses very consoling. I wish I did. I have been brooding over death a lot lately because of my advanced age and the precarious state of the world. I have my consolations. I am a writer and father, so I fantasize about people reading my books after Im gone, and I envision my son and daughter living good, fulfilling lives and possibly having children of their own. These wishful visions require civilization to continue, so I persuade myself that civilization, in spite of its manifest flaws, is pretty good and getting better. Thats how I manage my terror.

Further Reading:

I delve into the philosophical and spiritual implications of science in my two most recent books: Pay Attention: Sex, Death, and Science and Mind-Body Problems: Science, Subjectivity and Who We Really Are.

See my podcast Mind-Body Problems and in particular my recent chat with Sabine Hossenfelder: Consolations of Physics.

See also Meta-Post: Posts on Physics, a collection of my columns on physics.

This is an opinion and analysis article; the views expressed by theauthor or authorsare not necessarily those of Scientific American.

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Death, Physics and Wishful Thinking - Scientific American

As a college student I took three courses in physics. What we studied was called Newtonian physics since much of it was based on principles originally described by Sir Isaac Newton.

Another sort of physics, known as quantum physics, has been the focus of a great deal of work by modern physicists. Why start a pastors column with a mention of Newtonian and quantum physics? Certainly not because I am an expert in either one. We can learn something useful from the differences between these two types of physics, however.

Newtonian physics deals primarily with physical objects that can be seen or touched or both. Quantum physics is more concerned with subatomic particles which cannot be directly seen or touched in any ordinary human fashion. All I need you to understand about physics is that the laws of Newtonian physics do not work well for subatomic particles and that the laws of quantum physics do not work well for larger objects even though both types of physics deal with real physical matter. The search for an integrated theory that works for both large objects and subatomic particles has thus far failed to bring a fully satisfactory result.

We can conclude that reality is much more complicated than most people think. For the Christian this is no problem. Our faith is in a God who understands all there is about reality. Jesus, in John 8:32, says You shall know the truth, and the truth shall set you free. Though none of us is likely to know the whole truth about much of anything, God does.

Not having all the answers in life is not such a big deal if you know the one who does. The truth we need for daily living can be found with Gods help.

Pastor Dan York ministers at Dover Community Church.

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Physics, reality and God - Bonner County Daily Bee

The general theory of relativity, or simply general relativity, has been touted as the biggest scientific breakthrough of the 20th century. Published by Albert Einstein in 1915, the theory changed our understanding of Newtonian gravity as a force between bodies into a warping of the very fabric of space and time - spacetime. But the theory is not entirely foolproof and there are situations, particularly in the world of black holes and quantum physics, where cracks start to appear.

According to the principles of general relativity, black holes ought to be completely inert objects with singularities at their cores where the known laws of physics break down.

Professor Stephen Hawking was the first to put a dent in that model in the early Seventies when he revealed his Hawking radiation theory.

Based on his theoretical calculations, quantum effects near a black hole's event horizon - the point of no return - allow for thermal radiation to escape into space.

The process is also known as "blackbody radiation" and demonstrates, in essence, that black holes are not entirely black.

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Einstein even famously railed against the "topsy turvy" world of quantum physics, believing it was too messy and unprincipled.

Without a way to combine general relativity and quantum mechanics, the Sussex researchers used so-called effective field theory (EFT) to study the black hole singularity.

The theory stipulates gravity at the quantum level is very weak, which allows for some calculations that otherwise fall apart in the face of strong quantum gravity.

Dr Calmet said: "If you consider black holes within only general relativity, one can show that they have a singularity in their centres where the laws of physics as we know them must break down.

"It is hoped that when quantum field theory is incorporated into general relativity, we might be able to find a new description of black holes."

With the aid of EFT, Dr Calmet and his colleague were able to find mathematical evidence of pressure within a black hole.

According to astrophysicist Paul Sutter, this is the same type of pressure hot air exerts on the inside of a balloon.

However, because the model only works with weak quantum gravity, while neglecting strong gravity, it cannot be used to completely explain black hole behaviour.

Dr Calmet added: "Our work is a step in this direction, and although the pressure exerted by the black hole that we were studying is tiny, the fact that it is present opens up multiple new possibilities, spanning the study of astrophysics, particle physics and quantum physics."

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Black hole breakthrough as Einstein's theory challenged with find: 'Might need a new one' - Daily Express

$968 million have been awarded to research initiatives

The Office of Research published record-breaking annual funding with an increase of $27 million from last year. This years $968 million will fund a range of research topics across various departments.

A primary contributor to this years growth came from increased funding related to public health and medicine, Director of Marketing and Communications of the Office of Research AJ Cheline stated via email. The School of Medicine recognized the largest increase in funding, up $92 million from the previous year, totaling $368 million. Funding related to COVID-19 research totaled $42 million for the year.

Even with a focus on contributing to research on COVID-19-related issues, efforts in other departments continue. The Department of Physics and Astronomy has benefited from increased funding from the U.S. Department of Energy Office of Science, the National Science Foundation and other federal agencies. Projects funded included high energy particle theory, theoretical cosmology and astronomical observations at major telescopes.

The Department of Physics and Astronomy has seen steadily increasing external support over recent years, and this has allowed the department to recruit excellent graduate students and postdocs and expand the overall research efforts of the faculty, Professor John Conway of the Department of Physics said via email. At the federal level, support for basic scientific research has been very solid despite the great budget challenges we face as a nation.

Conway is involved in research projects on topics including the Higgs boson, neutrinos, dark matter and quantum physics, which were granted $7.5 million from the U.S. Department of Energy.

Other important medical projects such as the Adverse Childhood Experiences (ACEs) initiative had greatly benefited from $3 million funding this year. The collaboration project between UC Davis and Yolo County healthcare providers and agencies aims to increase support for patients by developing a trauma-informed network of care and universal screening for adverse childhood experiences.

The funds are being used to increase ACEs screening in primary care clinics that serve patients receiving MediCal, to improve workflow and communication from providers, patients, and buffering services, Principle Investigator Professor Leigh Ann Simmons said in an email. Among these services include food or housing assistance and employment assistance.

Written by: Christine Lee campus@theaggie.org

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Office of Research reports record-breaking funding - The Aggie - The Aggie

Sep 27, 2021(Nanowerk News) Imagine stacking two sheets of graphene the 2D form of graphite, or the pencil at your hand in which the carbon atoms form a hexagonal lattice and twist the top sheet out of alignment with the sheet below, yielding a periodic arrangement of atoms named moir pattern.Do you know that at a twisted angle of about 1o people now call it the magic angle the system could exhibit very exotic behaviours such as becoming an insulator, a metal or even a superconductor? Can you imagine the same carbon atom in your pencil (graphite) becoming a superconductor when twisted to the magic angle? It indeed did as people discovered it in 2018, but why?A team of researchers from the Department of Physics at the University of Hong Kong (HKU) and their collaborators have succeeded in discovering a bona fide topological Mott insulator in twisted bilayer graphene model.The findings have been published in a renowned journal Nature Communications ("Realization of topological Mott insulator in a twisted bilayer graphene lattice model").Moir pattern in twisted bilayer graphene. The twisted angle =4.41o and there are 676 Carbon atoms in a moir unit cell. (Image: Dr Bin-Bin CHEN)The reasons behind these exciting phenomena are the frontiers of condensed matter physics and quantum material research, both experimental, theoretical and computational, usually in combined form. The basic understanding up to now is that once the two graphene sheets form moir patterns at the magic angles, the energy bands of electrons in the twisted bilayer graphene become almost flat, in other words, the velocity of the electrons on the lattice becomes considerably lower than usual (compared to that in single-layer graphene or graphite our pencil), thus, the density of the electrons for this specific energy is tremendously large and the electrons can interact with each other strongly, giving rise to many unexpected states, e.g., the super-conductor, quantum Hall effect.As a result, the behaviour of the electron is dominated by the mutual repulsive (Coulomb) interactions, which leads to the emergence of the exotic phases discussed above that do not exist in single layers of graphene or our pencil. At low temperatures (below 10 Kelvin), when the electron number is tuned to fill integer degrees of freedom of the flat bands, it means some of these bands are fully occupied while leaving the others fully empty, the system then would form an electrically insulating phase. Moreover, when the electron number deviates from the integer fillings, the system becomes either a metal (with low electrical resistivity) or a superconductor (zero resistance).The phenomena of the magic angle twisted bilayer graphene are rich and profound, and physicists all over the world are now trying very hard to build proper microscopic models and find powerful computation methodologies to capture the mysterious properties of these models. Recently, Dr BinBin CHEN and Dr Zi Yang MENG from the Department of Physics, HKU, in collaboration with institutions from China and the US, succeeded in doing so with substantial progress. They have demystified the phase diagram of a model with a specific density of electrons and have identified the experimentally observed quantum anomalous Hall state, which is a novel quantum state with dissipationless edge current and is promising to be used as a basic component of your daily electronic gadgets, e.g. computer, smartphone.Quantum anomalous Hall effect in effective twisted bilayer graphene modelResearchers pay special attention to the =3 integer filling of the magic angle twisted bilayer graphene, since at the same filling case, the experiment shows that in the alignment of hexagonal boron nitride substrate, the electrons exhibit quantised Hall conductance xy=e2/h without exerting a magnetic field the so-called the quantum anomalous Hall (QAH) state.The QAH state is an interesting topological state with the bulk remaining insulating and the edge conducting electric current without dissipation! Till now, the mechanism of such QAH state is still under debate. In the work, researchers show that such an effect can be realised in a lattice model of twisted bilayer graphene in the strong coupling limit, and interpret the results in terms of a topological Mott insulator phase.Specifically, researchers present their theoretical study on the mechanism of QAH driven by projected Coulomb interactions. By employing extensive density-matrix renormalisation group simulations on the interacting lattice model, they identify a QAH phase with Hall conductance of xy=e2/h , which is separated from an insulating charge density wave (stripe) phase by a first-order quantum phase transition at c 0.12. To calculate the Hall conductance in the QAH phase, they actually follow Laughlins gedankenexperiment. That is, by inserting a flux slowly from 0 to 2 through the hole of the cylinder, we observe exactly one electron is pumped from the left edge to the right, corresponding to the quantized Hall conductance of xy=e2/h. This work addresses the currently popular question on the origin of QAH in twisted bilayer graphene at =3 filling.The first instance of topological Mott insulatorThe QAH state discovered from model computation purely comes from the unique properties of the Coulomb interaction in the magic-angle twisted bilayer graphene system. And it is the first example of such an interaction-driven topological quantum state of matter that has been unambiguously discovered. The impact of such discovery is even beyond the area of magic-angle twisted bilayer graphene and have responded to a proposal in the generic topological state of matter a decade ago.One of the reviewers, Dr Nick BULTINCK, a theoretical condensed matter theorist from the University of Oxford, gave a high rating of the work and said: In his seminal paper, Haldane has shown that one does not need a magnetic field to have electrons occupy topologically non-trivial extended states which respond to Laughlins adiabatic flux insertion by producing a quantised Hall current. The results in this work show that one does not even need a kinetic energy term in the Hamiltonian for this to occur.Indeed, not limited to the twisted bilayer graphene system, our work, for the first time, provides a Mott-Hubbard perspective for the QAH state driven by interactions only. Consequently, we clarified the long-standing mystery of the possible existence of the topological Mott insulator (TMI), the building block of the so-called information highway due to its ability to transfer electricity and information without loss.The famous Chinese-American physicist, Professor Shou-Cheng ZHANG (1963-2018) and his collaborators first proposed such a TMI state about a decade ago, and subsequently, various interaction models have been studied by many theorists. Among all the previous works, the kinetic terms play a crucial role in the emergence of the QAH, and therefore, the obtained state should not be dubbed as TMI. However, our model completely turns off the kinetic part and contains only the interactions to produce the TMI state. In this regard, our work bridges the two essential fields in condensed matter physics: topology and the strong correlation. Further extension of our model construction and unbiased quantum many-body computations can be accessed from here.Impact and future directionsAs the number of transistors in the chips of our computer is doubled every 18 months, the heat they generated accompanied with the electricity transfer is gradually becoming a severe problem. The discovery of quantum anomalous Hall effect is of great significance, as no dissipation of energy and no heat is generated in the edge. In practice, such a state is the building block of the information highway and is promising to be applied in the next-generation chip.The discovery of the QAH as the topological Mott insulator state in our model computation at filling =3 sheds light on the phases that occur in magic-angle twisted bilayer graphene. Further careful modelling and computation on the lattice models of the system would reveal the mechanism of the superconductivity and provide better tunability of these exotic phenomena in this and other 2D quantum moir material. The new findings also leave many open questions. For example, why is the topological Mott insulator state absent at other fillings of the band structure of the magic-angle twisted bilayer, how to properly study and compute the properties of the model away from integer fillings, etc?The answers to these questions might help physicists to fully demystify the magic in this material and design more exciting phases of matter in this and other 2D quantum moir materials currently being actively studied. Dr Meng added, And our research activity and expertise in 2D quantum materials can substantially boost this direction, which is the strategical research themes of HKU.

Originally posted here:

Physicists realize a topological Mott insulator in twisted bilayer graphene - Nanowerk

Researchers in the Department of Physics in Arts & Sciences at Washington University in St. Louis recently completed initial construction on XL-Calibur, a new balloon-borne telescope.

Henric Krawczynski, the Wayman Crow Professor of Physics, is leading a collaboration of 51 scientists from three countries the United States, Japan and Sweden on the project. Krawczynski and his group at Washington University developed XL-Calibur and its successful predecessor X-Calibur with the goal of unlocking the secrets of astrophysical black holes and neutron stars how do they form and grow? How fast do they spin? What strange physical phenomena do they generate?

By looking at the polarization of X-rays emitted from targets like the 14.8 solar mass black hole Cygnus X-1 and the relatively young neutron star in the center of the Crab Nebula, known as the Crab Pulsar, physicists can constrain the geometries of these objects, better understand the complex curved spacetime around them and possibly observe rare quantum effects predicted by quantum electrodynamics.

Krawczynski also anticipates capturing spin measurements for stellar-mass black holes, demonstrating techniques that can later be used to analyze supermassive black holes, which are thought to reside at the center of galaxies.

Lindsey LisaldaandAndrew West, graduate students in Krawczynskis research group, played major roles in designing and building XL-Calibur and its most important features. Electrical engineerRichard Boseand techniciansDana BraunandGarry Simburger, all in the Department of Physics,also worked closely with Lisalda and West to complete the project.

Lisalda collaborated with mechanical engineer Victor Guarino on the design of the optical bench, carefully crafting the carbon fiber and aluminum truss and its joints to be strong enough to withstand forces up to 16 times the force of Earths gravity.The optical bench was fabricated in the machine shop atWashington University byTodd Hardt,Kenny Schmidt andDennis Huelsman.

Earlier this month, the researchers packed up the telescope and shipped it to NASAs Wallops Flight Facility in Virginia, where it will be fitted with a pointing system and loaded into a gondola that can be suspended under a balloon for flight. The team plans to launch XL-Calibur from the Esrange Space Center in Sweden in April 2022 and from McMurdo Station in Antarctica in 2023.

Read more in The Ampersand about XL-Caliburs polarimeter, flight control systems and the remaining steps in its journey before launch.

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XL-Calibur telescope to examine the most extreme objects in the universe - Washington University in St. Louis Newsroom

The University of Maryland will lead a multi-institutional research effort that uses quantum simulation devices to gain insight into complex quantum systems.

The recently-founded NSF Quantum Leap Challenge Institute for Robust Quantum Simulation aims to advance quantum science and technology, have an impactful presence on quantum education and contribute to workforce development in quantum science.

The institute, funded by a $25 million five-year grant from the National Science Foundation, will be led by University of Maryland computer science professor Andrew Childs with collaboration from project partners at four other academic institutions. The research partners include Duke University, North Carolina State University, Princeton University and Yale University.

The institutes work will include training and mentoring graduate students and postdoctorates as well as engaging diverse groups in quantum science.

One way the institute plans to engage these diverse groups is by developing university classes in partnership with other universities, such as Morgan State University and North Carolina Central University, which are both historically Black institutions.

We have [education and outreach] programs at all levels, said Mohammad Hafezi, the institutes associate director for education. It starts from K-12, goes to undergraduate, graduate, postgraduate and general public. Each of them has their own subtleties and differences and programs. And our hope is to actually cover all of them.

[Dr. Amitabh Varshney named interim research VP at UMD]

Gretchen Campbell, a National Institute of Standards and Technology Joint Quantum Institute fellow and the associate director for diversity and inclusion, said getting the best and brightest people in the field means they need to be sure not to miss out on large chunks of our population.

Campbell hopes when people start to learn about quantum science, they get excited and think [this is] cool and a little different. And she hopes when quantum science is more accessible to a broader audience, this excitement turns into people becoming interested in STEM fields.

[The] industry and companies have really realized that theres really a need to have more people who are trained in quantum science or at least exposed to quantum science, Campbell said. This has also been happening at a time when, particularly in physics and computer science, weve also been really pushing to increase representation in science.

The team plans to evaluate their work and accomplishments by conducting an impact evaluation every six months to a year. The team also hopes to learn from other centers that are doing similar work in the U.S. and share their successful and unsuccessful experiences with them.

[UMD, IonQ join forces to create the nations first quantum computing lab in College Park]

Outside of engaging with students and professionals, the institute aims to advance quantum science by building a well-controlled, well-characterized quantum system that can reliably simulate the behavior of matter at small scales by combining theoretical studies with experimental implementations on several leading hardware platforms, according to the project abstract at the time it received the NSF grant.

Childs said that in the far future, chemical processes could be simulated using larger and more reliable quantum computers.

Theres a lot of potential to solve computational problems that are hard to handle with the computing devices that we have now, and if we could build quantum computers it would let us do more, Childs said.

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UMD leads multi-institutional quantum research institute, aims to boost diversity in STEM - The Diamondback

A progressive UK-based start-up, Zero Point Motion, is currently developing innovative high-performance sensors for navigation and precise positioning applications. Founded by Dr. Ying Lia Li in 2020, the early-stage start-up has set out to develop cost-effective chip-scale optical sensors that can be mass-produced.

Utilizing a combination of MEMS and PIC technology, Zero Point Motions optical sensors can generate a photonic readout of motion, which offers several unique advantages.

These include harnessing the quantum properties of light to create hardware solutions and devices that sense motion with 10,000 times greater precision than in todays consumer MEMS devices, such as smartphones.1

Furthermore, with Lis extensive research background and industry experience, the early-stage start-up is well-equipped to overcome the challenges faced in the high-profile sensor industry.

Li completed a PhD in experimental quantum physics at University College London, as well as winning two prestigious merit-based scholarships.

The first was awarded to Li by the Engineering and Physical Sciences Research Council (EPSRC) in 2017, enabling her to investigate sensor applications utilizing whispering gallery mode resonances. The other was awarded to Li by the Royal Academy of Engineering Intelligence Community in 2019, allowing her to initiate the prototyping of optomechanical sensors.2

Throughout her career and research, Li has produced pioneering work, including the invention of a type of chip-assisted plastic optical fiber printing method (patents granted in US & UK), as well as for her well-established innovation in optomechanics.

This kind of experience is what led to Li setting up the Zero Point Motion start-up in the hope of commercializing optomechanics, in particular the fabrication of sensors for applications, including positioning and navigation, as well as structural and health monitoring.

However, Li knew that constantly depending on research grants and funding for projects can be a precarious situation. Thus, to upscale production and produce significant volumes of optical sensors, careful management of the supply chain is vital.

Therefore, Lia recruited the help of two experts in the development of wireless chip technologies and low power ASICs, Pascal Herczog and Gordon Aspin, who are now Vice President and Executive Chairman of operations, respectively.

Both Aspin and Herczog have a wide array of experience and knowledge in technologies focused on targeted markets including automotive and smartphone industries as well as an understanding of how to manage and overcome the potential difficulties when transferring designs between foundries of different sizes.

This means that the start-up is strategically well-positioned to continually develop and shake up the market for high performance sensors for navigation and precision positioning.

Now, the primary objective for the start-up is to get its products to market as soon as possible and to start generating revenue. However, the company does not want to over-customize its products and instead intends to focus on establishing a standard line of sensors.

The challenge then becomes producing a standard line of sensors and devices that can be co-designed by simply introducing firmware updates or modifying algorithms in line with a given application.

Over the course of the next few years, the Zero Point Motion plans to open its own laboratory and offices and expand the current workforce to that of around twenty individuals. Additionally, the company has its sights set on producing two different variations of sensors with varying performance levels.

One line of sensor would focus on controlled movement seen in applications such as structural monitoring, image stabilization and industrial drones. The other line would concentrate its design on high-precision tracking over prolonged periods of time without GPS enabling enhanced positioning and timing, regardless of connectivity.

Li has no doubt that the performance advantages of the start-ups current MEMS, PIC and ASIC supply chain will meet these challenges and facilitate the future expansion and fulfill the demand of todays market.

With the quantum industry already embracing Zero Point Motions devices, there is plenty of opportunity for Zero Point Motions high performance sensors to support innovation in the engineering and navigation industries.

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

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Innovative High Performance Sensors for Navigation and Precision Positioning - AZoSensors

Sitting in the top-floor study of his childhood Niskayuna home, Paul LaViolette puzzles over the deepest questions of the universe.

Massive bound volumes of his doctoral thesis in general systems theory, old science journals and a series of volumes of his self-published book line shelves in the house designed by famous GE architect Victor Civkin.

Working through dense calculations and decoding pictures of faraway stars and galaxies, LaViolette has spent decades refining his own theories about the universe. He doesnt work with massive telescopes or particle accelerators, tools used by enormous teams of scientists across the planet to refine their theories about how the universe originated and how it operates. But he asks the same questions. Where did the universe come from and how did it start? How is matter created? Why does it appear the universe is expanding so quickly?

LaViolette, though, has come up with very different answers to those questions than the mainstream scientists who populate university faculties, government agencies and research laboratories.

I disproved the Big Bang theory, LaViolette said in a phone call last month, adding that he recently published a pair of papers this summer in the International Journal of Astronomy and Astrophysics, a peer-reviewed journal, outlining his definitive takedown of what has been considered the definitive scientific model of the origin of the universe.

The first articles title, Expanding or Static Universe: Emergence of a New Paradigm, understates what LaViolette is proposing: scrap the dominant theory of the history of the universe taught in nearly every grade in nearly every school in the country.

The Big Bang theory basically holds that the history of our universe traces back to a single point of energy that exploded into existence and over a long period of time expanded into the universe we know today.

But LaViolette thinks most scientists are looking at the data from the wrong perspective, misunderstanding shifts on the light spectrum as they observe faraway galaxies as evidence of an expanding universe. Rather, he thinks the so-called redshift most scientists point to as evidence of an expanding universe is just a sign of the loss of energy that photons from distant galaxies have as they travel through space. That theory of the redshift, known as the tired light theory, has been around for decades. But LaViolette has repurposed it to demonstrate that a static universe, one that is not expanding as is commonly understood, makes a simpler explanation of numerous astronomical phenomena. His paper presents a series of cosmology tests, used to test different theories of the universe against various data sets, and argues that a static model of the universe bests an expanding model of the universe on all of the tests he presents unless various assumptions are added into the models about anything from the angles of galaxies to factors about their distance. Even then, LaViolette argues, assumptions made to improve the performance of a traditional expanding-universe model on one test worsen the theorys performance on other tests.

In overview, it is concluded that a static universe cosmology must be sought to explain the origin of the universe, he declared in the papers abstract.

His theory

LaViolette, now in his 70s, grew up in Niskayuna, where his parents worked in the areas scientific research industry, including at Knolls labs. After two years of high school in Niskayuna, his family moved to Greece. He studied at Johns Hopkins and University of Chicago, and worked at the Harvard School of Public Health. During the Vietnam era, he conducted research into ventilation systems used on masks. He earned a patent on new mask technology in 1973, but said he was unable to gain traction as he spent a few years trying to sell his idea he couldnt induce the wide-scale adoption he had hoped for.

Because they used to make [masks] a certain way, they didnt want to change, he said.

He eventually moved to Portland, Oregon, to study at the countrys only doctoral program in general systems theory at the time. As he worked on his tome of a dissertation, LaViolette started to think of the universe in terms of an open system, one where matter could effectively generate out of itself, especially in the most volatile parts of the universe.

It was the longest Ph.D. in the history of the program, and it still is, he said of his dissertation. They bring it out to intimidate people.

Since then he has continued to develop and fine-tune his arguments against an expanding-universe model, hoping his ideas would gain traction.

In an article titled Is the Universe Really Expanding? published in 1985, LaViolette relies on a smaller set of cosmology tests and data than his most recent papers to build a case that a static-universe model can offer a better explanation than the Big Bang.

I thought that one had disproved Big Bang, he said of the earlier paper.

The theory, though, has proved stubbornly resistant to its demise. As scientists collect more and more data about the universe, they have fine-tuned their own models, theories and equations but major holes and uncertainty still persist (no model has yet tied together large-scale and subatomic theories of physics, for example).

If mainstream science ever does adopt LaViolettes theory of the universe, it will spell doom for many fundamental tenets of physics and astronomy. No black holes, he said. No quantum mechanics (which helps explain physics at the scale of atoms and subatomic particles). No Einsteins theory of general relativity (which helps explain gravitational physics at a large scale).

You have to throw it out, he said. Even the ages of stars change.

He has also inched toward his own novel cosmology a broad theory of the origin of the universe developed over decades called subquantum kinetics. He has written numerous editions of a book on the topic. The model, which replaces the void left by the destruction wrought by disproving the Big Bang theory, predicts that a cosmic ether at the subatomic level is capable of producing energy fluctuations that in some scenarios can nucleate a subatomic particle. He calls it a continuous-creation theory, where matter is constantly being created within a static universe.

Matter produces more matter its like biological reproduction in a way, he said.

LaViolette argues that most scientists stubbornly adhere to the law of energy conservation that the total amount of energy in a system remains constant and should instead accept a model where new energy can emerge.

They [mainstream scientists] believe in taking the first law of thermodynamics and applying it down to the minutest detail, he said. The whole thing is based on faith that energy is conserved so rigorously.

He said mainstream scientists are often clouded by their beliefs in their own models and create theoretical assumptions that ensure those models work. Using an unflattering analogy to tree monkeys, he explained that scientists will hold fast to the Big Bang theory until an alternative gains broader acceptance fearing the metaphorical limb.

Theyve already assumed their model is correct. They dont want to admit another way of looking at things, he said. Physicists, they are like monkeys clinging to a tree. Unless they see another tree to jump to, they wont.

Huge Unknowns

Heidi Jo Newberg, an astrophysicist at Rensselaer Polytechnic Institute known for her work understanding the structure of the Milky Way galaxy, earths home galaxy, said the broader field often hears from out-of-the-box thinkers with a hodgepodge of their own theories. She said the ideas fall on a wide spectrum of seriousness and rigor.

I regularly get books and manuscripts from people all of the time, and they range from people who are just crazy, have crazy, crazy things, to people who are very knowledgeable and have a really good sense of science and terminology and the fields they are in, she said in an interview.

While Newberg had not studied LaViolettes recent papers and did not offer direct support or rebuttal of his theory, she noted that it was published in a refereed journal and appeared to be scientifically rigorous.

It looks to me like this is on the more knowledgeable side of it, she said.

Newberg explained that the scientific fields dominant understanding of the origin of the universe is both highly detailed and supported by vast data, while also containing huge holes filled by yet-to-be-proven explanations.

There are a lot of things we think we do know and some of them are really amazing, but there is a huge amount, almost an embarrassing amount, we dont understand about our standard model, she said.

The standard model the framework broadly accepted by scientists and taught at different academic levels holds that our universe expanded out of an infinitely dense source point, Newberg said, expanding at fluctuating rates over vast amounts of time as gravitational forces pulled together galaxies and ever-bigger astronomical structures.

Scientists have accumulated enormous quantities of data on the size and scale of different formations in the universe. The intergalactic distances light must travel to be observed by satellites and telescopes offers a glimpse of stars as they existed billions of years ago.

We have a kind of working understanding of the history of the universe that explains everything that we see, she said. In the last few decades, we have been in a really, really strong period for constraining the universe and how its evolved.

While much of the data lends further support to the standard model and further refines scientific understanding of different dimensions of that model, the explanations underpinning the standard model rely on some theoretical patches to cover enormous gaps of knowledge.

For the standard model to work, for instance, scientists posit the existence of so-called dark matter, which accounts for the majority of the matter in the universe and helps explain various observations and patterns in astronomy.

But one big problem remains for dark matter theorists: After decades of theorizing and building highly tuned detectors aimed at identifying an actual dark matter particle, scientists have still come up short in doing so.

People have been looking for 30 years. We think eventually someone will find this, Newberg said, noting that the theoretical presence of dark matter helps tie together numerous theories around how things work on a large scale.

There are very big pieces that are notional, she said of the dominant cosmological model. Dark matter is notional, but when you put it in everything works.

For LaViolette, the holes in the standard model bolster his theory that it doesnt actually hold together without the ad-hoc assumptions he said scientists plug into their equations to make their theories work. He argues that scientists at mainstream institutions are too wedded to their theories to accept an alternative model or allow consideration of paradigm-shifting ideas.

Newberg countered that scientists broadly are independently minded fact-finders who regularly contest one anothers theories, ideas, data and approaches, forcing further refinement and defense of their ideas on a regular basis. I think the science establishment isnt so monolithic as people think, she said. We are all individuals and we argue all the time. In my work, Im constantly challenged by people who have all the data that is available and make sure what I do is consistent with what we know.

Newberg said it is possible that cosmology may be more susceptible to a dramatic paradigm shift because of the large unknowns and vast space and time at play. The mystique and allure of questions about the universe and its history serve as a further accelerant that draws contrarian thinkers to propose ideas and theories that counter the dominant model. She said she is working with an artist-inventor who proposed to her an alternative idea for a space telescope.

Where you have a big problem that is very exciting and interesting, and has such huge unknowns, thats going to be a big draw for people that are really interestingand in some ways, there is an opportunity for someone to come with an idea from outside the field that changes everything, she said.

She noted that over the years various scientists have proffered alternative theories to different components of the standard model, but that they dont hold up against a deluge of observational data the same way theories attached to the standard expanding-universe model do. An alternative theory might explain one phenomenon but not another. Among most scientists, though, there is no leading competitor to the Big Bang theory, she said.

I think there is an opportunity to come up with other versions of cosmology, but its challenging to fit all of the data, she said. Its easy to come up with something that is consistent with some things but not everything.

For his part, LaViolette isnt waiting for the rest of science to catch up, working on a new edition to his book, Subquantum Kinetics: A Systems Approach to Physics and Cosmology, and taking comfort in his confidence that science will eventually follow the path he has tried to lay out. Whether or not hes around to see the day that happens is another question.

I totally believe this is the way physics will go in the future, he said.

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Niskayuna man believes he solved mystery of the universe - The Daily Gazette