Predicting Everything

A breakthrough in theoretical physics is an important step toward predicting the behavior of the fundamental matter of which our world is built. It can be used to calculate systems of enormous quantities of quantum particles, a feat thought impossible before.


The new University of Copenhagen research may prove of great importance for the design of quantum computers and could even be a map to superconductors that function at room temperature. The paper is published in the journal Physical Review X.

On the fringes of theoretical physics, Berislav Buca investigates the nearly impossible by way of "exotic" mathematics. His latest theory is no exception. By making it possible to calculate the dynamics, i.e., movements and interactions, of systems with enormous quantities of quantum particles, it has delivered something that had been written off in physics. An impossibility made possible.  READ MORE...

Quantum Systems Defy Freezing Logic

Researchers investigated the Mpemba effect in quantum systems, a phenomenon where hotter water can freeze faster than cooler water. This quantum Mpemba effect retains memory of its initial conditions, affecting its thermal relaxation later. The team used two systems with quantum dots and discovered the thermal quantum Mpemba effect across various conditions, suggesting possible broader applications beyond thermal analysis.



Hotter quantum systems can cool faster than initially colder equivalents.

Does hot water freeze faster than cold water? Aristotle may have been the first to tackle this question that later became known as the Mpemba effect.

This phenomenon originally referred to the non-monotonic initial temperature dependence of the freezing start time, but it has been observed in various systems — including colloids — and has also become known as a mysterious relaxation phenomenon that depends on initial conditions.

What Is the Mpemba Effect?
The Mpemba effect is a counterintuitive phenomenon where hot water can freeze faster than cold water under certain conditions. Named after Erasto Mpemba, a Tanzanian student who observed this effect in the 1960s and subsequently brought it to the attention of the scientific community, the phenomenon has been a topic of curiosity for centuries, with references dating back to the likes of Aristotle. The exact cause of the Mpemba effect is still a topic of debate among scientists.

Recent Findings
Now, a team of researchers from Kyoto University and the Tokyo University of Agriculture and Technology has shown that the temperature quantum Mpemba effect can be realized over a wide range of initial conditions.

“The quantum Mpemba effect bears the memory of initial conditions that result in anomalous thermal relaxation at later times,” explains project leader and co-author Hisao Hayakawa at KyotoU’s Yukawa Institute for Theoretical Physics.  READ MORE...

Quantum Computing 10 Times More Efficient

In the world of quantum error correction, an underdog is coming for the king.

Last week, new simulations from two groups reported that a rising class of quantum error-correcting codes is more efficient by an order of magnitude than the current gold standard, known as the surface code. 

The codes all work by transforming a horde of error-prone qubits into a much smaller band of “protected” qubits that rarely make mistakes. But in the two simulations, low-density parity check — or LDPC — codes could make protected qubits out of 10 to 15 times fewer raw qubits than the surface code. 

Neither group has implemented these simulated leaps in actual hardware, but the experimental blueprints suggest that these codes, or codes like them, could hasten the arrival of more capable quantum devices.

“It really looks like it’s coming to fruition,” said Daniel Gottesman of the University of Maryland, who studies LDPC codes but was not involved in the recent studies. “These [codes] could be practical things that can greatly improve our ability to make quantum computers.”

Classical computers run on bits that rarely misfire. But the particle-like objects — qubits — that power quantum computers lose their quantum mojo when just about anything jostles them out of their delicate state. 

To coax future qubits into usefulness, researchers plan to use quantum error correction, the practice of using extra qubits to redundantly encode information. It’s similar in spirit to protecting a message from static by speaking each word twice, spreading out the information among more characters.

The Canonical King
In 1998, Alexei Kitaev of the California Institute of Technology and Sergey Bravyi, then of the Landau Institute for Theoretical Physics in Russia, introduced the quantum error-correcting surface code. It organizes qubits into a square grid and executes something like a game of Minesweeper: Each qubit connects to four neighbors, so checking designated helper qubits allows you to discreetly snoop on four data-carrying qubits. 

Depending on whether the check returns a 0 or a 1, you can infer whether some of the neighbors have erred. By checking around the board, you can deduce where the errors are and fix them.  READ MORE...

Quantum Physics Phenomenon of Materials

Credit: Pixabay/CC0 Public Domain

Researchers at Northeastern have discovered a new quantum phenomenon in a specific class of materials, called antiferromagnetic insulators, that could yield new ways of powering "spintronic" and other technological devices of the future.


The discovery illuminates "how heat flows in a magnetic insulator, [and] how [researchers] can detect that heat flow," says Gregory Fiete, a physics professor at Northeastern and co-author of the research. The novel effects, published in Nature Physics this week and demonstrated experimentally, were observed by combining lanthanum ferrite (LaFeO3) with a layer of platinum or tungsten.

"That layered coupling is what is responsible for the phenomenon," says Arun Bansil, university distinguished professor in the Department of Physics at Northeastern, who also took part in the study.

The discovery may have numerous potential applications, such as improving heat sensors, waste-heat recycling, and other thermoelectric technologies, Bansil says. This phenomenon could even lead to development of a new power source for these—and other—budding technologies. Northeastern graduate student Matt Matzelle and Bernardo Barbiellini, a computational and theoretical physicist at the Lappeenranta University of Technology, who is currently visiting Northeastern, participated in the research.

Illustrating the teams' findings requires considerable magnification (literally) to observe the world of atomic-scale particles—specifically, at the nano-lives of electrons. It also requires an understanding of several properties of electrons—that they possess something called "spin," have a charge, and can, when moving through a material, generate heat flow.

Electron spin, or angular momentum, describes a fundamental property of electrons defined in one of two potential states: Up or down. There are many different ways these "up or down" spins of the electrons (also thought of as north-south poles) orient themselves in space, which in turn gives rise to different types of magnetisms. It all depends, Bansil says, on the ways atoms are patterned in a given material.  READ MORE...

Limits of Artificial Intelligence

Humans are usually pretty good at recognizing when they get things wrong, but artificial intelligence systems are not. According to a new study, AI generally suffers from inherent limitations due to a century-old mathematical paradox.

Like some people, AI systems often have a degree of confidence that far exceeds their actual abilities. And like an overconfident person, many AI systems don't know when they're making mistakes. Sometimes it's even more difficult for an AI system to realize when it's making a mistake than to produce a correct result.

Researchers from the University of Cambridge and the University of Oslo say that instability is the Achilles' heel of modern AI and that a mathematical paradox shows AI's limitations. Neural networks, the state of the art tool in AI, roughly mimic the links between neurons in the brain. The researchers show that there are problems where stable and accurate neural networks exist, yet no algorithm can produce such a network. Only in specific cases can algorithms compute stable and accurate neural networks.

The researchers propose a classification theory describing when neural networks can be trained to provide a trustworthy AI system under certain specific conditions. Their results are reported in the Proceedings of the National Academy of Sciences.

Deep learning, the leading AI technology for pattern recognition, has been the subject of numerous breathless headlines. Examples include diagnosing disease more accurately than physicians or preventing road accidents through autonomous driving. However, many deep learning systems are untrustworthy and easy to fool.

"Many AI systems are unstable, and it's becoming a major liability, especially as they are increasingly used in high-risk areas such as disease diagnosis or autonomous vehicles," said co-author Professor Anders Hansen from Cambridge's Department of Applied Mathematics and Theoretical Physics. "If AI systems are used in areas where they can do real harm if they go wrong, trust in those systems has got to be the top priority."  READ MORE...

A Pixelated Space...

The search for signatures of quantum gravity forges ahead.
Sand dunes seen from afar seem smooth and unwrinkled, like silk sheets spread across the desert. But a closer inspection reveals much more. As you approach the dunes, you may notice ripples in the sand. Touch the surface and you would find individual grains. The same is true for digital images: zoom far enough into an apparently perfect portrait and you will discover the distinct pixels that make the picture.

The universe itself may be similarly pixelated. Scientists such as Rana Adhikari, professor of physics at Caltech, think the space we live in may not be perfectly smooth but rather made of incredibly small discrete units. “A spacetime pixel is so small that if you were to enlarge things so that it becomes the size of a grain of sand, then atoms would be as large as galaxies,” he says.

Adhikari and scientists around the world are on the hunt for this pixelation because it is a prediction of quantum gravity, one of the deepest physics mysteries of our time. Quantum gravity refers to a set of theories, including string theory, that seeks to unify the macroscopic world of gravity, governed by general relativity, with the microscopic world of quantum physics. At the core of the mystery is the question of whether gravity, and the spacetime it inhabits, can be “quantized,” or broken down into individual components, a hallmark of the quantum world.

“Sometimes there is a misinterpretation in science communication that implies quantum mechanics and gravity are irreconcilable,” says Cliff Cheung, Caltech professor of theoretical physics. “But we know from experiments that we can do quantum mechanics on this planet, which has gravity, so clearly they are consistent. The problems come up when you ask subtle questions about black holes or try to merge the theories at very short distance scales.”

Because of the incredibly small scales in question, some scientists have deemed finding evidence of quantum gravity in the foreseeable future to be an impossible task. Although researchers have come up with ideas for how they might find clues to its existence—around black holes; in the early universe; or even using LIGO, the National Science Foundation-funded observatories that detect gravitational waves—no one has yet turned up any hints of quantum gravity in nature.  READ MORE...

TIME: Past - Present - Future

Time is a commodity that is limited in its nature especially for all living things but time is also conceptualized with a PAST, PRESENT, and a FUTURE; although, we never see the past living in the present that always seems to lean more directly into the future...  since time moves forward not backward; and, we accept the past as what has been simply because we can read the records.  BUT, time is somewhat elusive in that we can never see what just happened and what just happened is never behind us even when we are walking backwards into our future...  so where did our immediate past go?

The breeze that blows by...  comes and goes but as it touches our bodies is all we know of its existence other than what we may observe but where it came from has disappeared into our past never to be seen again so we do not know for sure if the conditions that brought the breeze to us still there...  or perhaps the past goes into some kind of holding dimension.

Using telescopes we can see where space came from and where it is going but that ability stops as we observe the life we are living.  There will always be cars behind us on the interstate but we are all moving forward at the same relative time and even though we see a landscape behind us as we drive by, the conditions of that landscape are different than when we were just there...  just as every millisecond of our present is different so too is every millisecond of our past.

SO...  again...  where does our past go and that it goes so fast we cannot return?

A jet stream is a visual reminder and the actual past of a fast moving aircraft as it moves into its future pausing less than a nanosecond in its present; however, the physical aircraft's past is never seen as if it never been there in the first place yet we see its reminder as it floats behind eventually dissipating.    

Grave Stones are a reminder of someone's past but that is not exactly what I am talking about...  I want to know where our immediate past goes when we are still alive always moving into our future...  this is the question that bothers me and to which there is no easy reply and only speculative proof and our existence in our future that it actually happened at all or why we can never return.