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Archive for the ‘quantum physics’ category: Page 490

Apr 15, 2021

In a first, scientists watch 2D puddles of electrons spontaneously emerge in a 3D superconducting material

Posted by in categories: particle physics, quantum physics

Creating a two-dimensional material, just a few atoms thick, is often an arduous process requiring sophisticated equipment. So scientists were surprised to see 2D puddles emerge inside a three-dimensional superconductor—a material that allows electrons to travel with 100% efficiency and zero resistance—with no prompting.

Within those puddles, superconducting electrons acted as if they were confined inside an incredibly thin, sheet-like plane, a situation that requires them to somehow cross over to another dimension, where different rules of quantum physics apply.

“This is a tantalizing example of emergent behavior, which is often difficult or impossible to replicate by trying to engineer it from scratch,” said Hari Manoharan, a professor at Stanford University and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at the Department of Energy’s SLAC National Accelerator Laboratory, who led the research.

Apr 14, 2021

Fast-spinning black holes narrow the search for dark matter particles

Posted by in categories: cosmology, particle physics, quantum physics

Ultralight bosons are hypothetical particles whose mass is predicted to be less than a billionth the mass of an electron. They interact relatively little with their surroundings and have thus far eluded searches to confirm their existence. If they exist, ultralight bosons such as axions would likely be a form of dark matter, the mysterious, invisible stuff that makes up 85 percent of the matter in the universe.

Now, physicists at MIT’s LIGO Laboratory have searched for ultralight bosons using black holes—objects that are mind-bending orders of magnitude more massive than the particles themselves. According to the predictions of quantum theory, a black hole of a certain mass should pull in clouds of ultralight bosons, which in turn should collectively slow down a black hole’s spin. If the particles exist, then all black holes of a particular mass should have relatively low spins.

But the physicists have found that two previously detected black holes are spinning too fast to have been affected by any ultralight bosons. Because of their large spins, the black holes’ existence rules out the existence of ultralight bosons with masses between 1.3×10-13 electronvolts and 2.7×10-13 electronvolts—around a quintillionth the mass of an electron.

Apr 14, 2021

Researchers develop new method for putting quantum correlations to the test

Posted by in categories: computing, information science, quantum physics

Physicists from Swansea University are part of an international research collaboration which has identified a new technique for testing the quality of quantum correlations.

Quantum computers run their algorithms on large quantum systems of many parts, called qubits, by creating quantum correlations across all of them. It is important to verify that the actual computation procedures lead to quantum correlations of desired quality.

However, carrying out these checks is resource-intensive as the number of tests required grows exponentially with the number of qubits involved.

Apr 13, 2021

Researchers report breakthrough that enables practical semiconductor spintronics

Posted by in categories: computing, particle physics, quantum physics

It may be possible in the future to use information technology where electron spin is used to store, process and transfer information in quantum computers. It has long been the goal of scientists to be able to use spin-based quantum information technology at room temperature. A team of researchers from Sweden, Finland and Japan have now constructed a semiconductor component in which information can be efficiently exchanged between electron spin and light at room temperature and above. The new method is described in an article published in Nature Photonics.

It is well known that electrons have a negative charge; they also have another property called spin. This may prove instrumental in the advance of . To put it simply, we can imagine the electron rotating around its own axis, similar to the way in which the Earth rotates around its own axis. Spintronics—a promising candidate for future information technology—uses this quantum property of electrons to store, process and transfer information. This brings important benefits, such as higher speed and lower energy consumption than traditional electronics.

Developments in spintronics in recent decades have been based on the use of metals, and these have been highly significant for the possibility of storing large amounts of data. There would, however, be several advantages in using spintronics based on semiconductors, in the same way that semiconductors form the backbone of today’s electronics and photonics.

Apr 13, 2021

The observation of Kardar-Parisi-Zhang hydrodynamics in a quantum material

Posted by in categories: information science, mathematics, particle physics, quantum physics

Classical hydrodynamics laws can be very useful for describing the behavior of systems composed of many particles (i.e., many-body systems) after they reach a local state of equilibrium. These laws are expressed by so-called hydrodynamical equations, a set of mathematical equations that describe the movement of water or other fluids.

Researchers at Oak Ridge National Laboratory and University of California, Berkeley (UC Berkeley) have recently carried out a study exploring the hydrodynamics of a quantum Heisenberg spin-1/2 chain. Their paper, published in Nature Physics, shows that the spin dynamics of a 1D Heisenberg antiferromagnet (i.e., KCuF3) could be effectively described by a dynamical exponent aligned with the so-called Kardar-Parisi-Zhang universality class.

“Joel Moore and I have known each other for many years and we both have an interest in quantum magnets as a place where we can explore and test new ideas in physics; my interests are experimental and Joel’s are theoretical,” Alan Tennant, one of the researchers who carried out the study, told Phys.org. “For a long time, we have both been interested in temperature in quantum systems, an area where a number of really new insights have come along recently, but we had not worked together on any projects.”

Apr 13, 2021

A phonon laser: Coherent vibrations from a self-breathing resonator

Posted by in categories: particle physics, quantum physics

Circa 2020


Lasing—the emission of a collimated light beam of light with a well-defined wavelength (color) and phase—results from a self-organization process, in which a collection of emission centers synchronizes itself to produce identical light particles (photons). A similar self-organized synchronization phenomenon can also lead to the generation of coherent vibrations—a phonon laser, where phonon denotes, in analogy to photons, the quantum particles of sound.

Photon lasing was first demonstrated approximately 60 years ago and, coincidentally, 60 years after its prediction by Albert Einstein. This stimulated emission of amplified found an unprecedented number of scientific and technological applications in multiple areas.

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Apr 13, 2021

Physics without time

Posted by in categories: information science, quantum physics

Place one clock at the top of a mountain. Place another on the beach. Eventually, you’ll see that each clock tells a different time. Why?


In his book “The Order of Time,” Italian theoretical physicist Carlo Rovelli suggests that our perception of time — our sense that time is forever flowing forward — could be a highly subjective projection. After all, when you look at reality on the smallest scale (using equations of quantum gravity, at least), time vanishes.

“If I observe the microscopic state of things,” writes Rovelli, “then the difference between past and future vanishes … in the elementary grammar of things, there is no distinction between ‘cause’ and ‘effect.’”

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Apr 13, 2021

Counting single photons at unprecedented rates

Posted by in category: quantum physics

In high-end 21st century communications, information travels in the form of a stream of light pulses typically traveling through fiber optic cables. Each pulse can be as faint as a single photon, the smallest possible unit (quantum) of light. The speed at which such systems can operate depends critically on how fast and how accurately detectors on the receiving end can discriminate and process those photons.

Now scientists at the National institute of Standards and Technology (NIST) have devised a method that can detect individual photons at a rate 10 times faster than the best existing technology, with lower error rates, higher detection efficiency, and less noise.

“While classical communication and detection can operate at blazing speeds, , which need that ultimate sensitivity for those faintest of pulses, are limited to much lower speeds,” said group leader Alan Migdall. “Combining that ultimate sensitivity with the ability to achieve the counting of photons at has been a long-standing challenge. Here we are pushing both performance limits all in the same device.”

Apr 11, 2021

Light Forms Crystal-Like Structure On Computer Chip

Posted by in categories: computing, particle physics, quantum physics

Circa 2014 essentially this could make endless computer chips from light.


Princeton researchers have managed to cause light to behave like a crystal within a specialized computer chip, according to a recent paper. This is the first time anyone has accomplished this effect in a lab.

Here’s why it’s so hard: Atoms can easily form solids, liquids, and gasses, because when they come into contact they push and pull on each other. That push and pull forms the underlying structure of all matter. Light particles, or photons, do not typically interact with one another, according to Dr. Andrew Houck, a professor of electrical engineering at Princeton and an author on the study. The trick of this research was forcing them to do just that.

Continue reading “Light Forms Crystal-Like Structure On Computer Chip” »

Apr 11, 2021

Quantum computer based on shuttling ions is built by Honeywell

Posted by in categories: computing, quantum physics

Design could allow large numbers of qubits to be integrated in one device.