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“We also demonstrated that even very low-power microwave pulses can be detected efficiently using our protocol.”

A team of scientists has devised a means of using quantum mechanics to “view” objects indirectly. The new method could improve measurements for quantum computers and other systems. It brings together the quantum and classical worlds.

Continue reading “Scientists can now ‘see’ things without ‘looking’ at them using a new quantum technique” »

They have found no signs of the event yet.

Deep in Italy’s Gran Sasso mountains, in the National Institute for Nuclear Physics’ (INFN) underground laboratories, researchers have been searching for proof of a very small violation of a fundamental quantum tenet called the Pauli exclusion principle, according to an article by Phys.org published on Monday.

The principle, that is applied to everything, dictates that electrons can only arrange themselves in certain specific ways in atoms. These arrangements make it so we are made of solid matter.

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A research group led by Prof. Wu Kaifeng from the Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences recently reported the successful initialization, coherent quantum-state control, and readout of spins at room temperature using solution-grown quantum dots, which represents an important advance in quantum information science.

The study was published in Nature Nanotechnology on Dec 19th.

Continue reading “Coherent manipulation of spin qubits at room temperature” »

We see the world around us because light is being absorbed by specialized cells in our retina. But can vision happen without any absorption at all—without even a single particle of light? Surprisingly, the answer is yes.

Imagine that you have a camera cartridge that might contain a roll of photographic film. The roll is so sensitive that coming into contact with even a single photon would destroy it. With our everyday classical means there is no way there’s no way to know whether there’s film in the cartridge, but in the quantum world it can be done. Anton Zeilinger, one of the winners of the 2022 Nobel Prize in Physics, was the first to experimentally implement the idea of an interaction-free experiment using optics.

Now, in a study exploring the connection between the quantum and classical worlds, Shruti Dogra, John J. McCord, and Gheorghe Sorin Paraoanu of Aalto University have discovered a new and much more effective way to carry out interaction-free experiments. The team used transmon devices—superconducting circuits that are relatively large but still show quantum behavior—to detect the presence of microwave pulses generated by classical instruments. Their research was recently published in Nature Communications.

For a long time, researchers assumed that phonons could not contribute to the thermal Hall effect because of their lack of charge and spin. New work challenges this assumption.

How heat flows in interacting quantum many-body systems is one of the most interesting open problems in condensed-matter physics. Understanding thermal transport is particularly challenging in systems where charge-carrier contributions to energy transport are strongly suppressed, such as in insulators and superconductors. In such systems, heat transport cannot therefore be understood in terms of electronic carriers alone. In insulators, acoustic phonons are among the main energy carriers in an insulator. However, determining how and to what extent phonons contribute to heat transport in a material is the Achilles’ heel of interpreting thermal conductivity measurements. In particular, whether or not phonons can contribute to the thermal Hall effect—in which a temperature gradient in one direction produces heat flow in a perpendicular direction—remains an open question.

A pressing quest in the field of nanoelectronics is the search for a material that could replace silicon. Graphene has seemed promising for decades. But its potential has faltered along the way, due to damaging processing methods and the lack of a new electronics paradigm to embrace it. With silicon nearly maxed out in its ability to accommodate faster computing, the next big nanoelectronics platform is needed now more than ever.

Walter de Heer, Regents’ Professor in the School of Physics at the Georgia Institute of Technology, has taken a critical step forward in making the case for a successor to silicon. De Heer and his collaborators have developed a new nanoelectronics platform based on graphene —a single sheet of carbon atoms. The technology is compatible with conventional microelectronics manufacturing, a necessity for any viable alternative to silicon.

In the course of their research, published in Nature Communications, the team may have also discovered a new quasiparticle. Their discovery could lead to manufacturing smaller, faster, more efficient and more sustainable computer chips, and has potential implications for quantum and high-performance computing.

In physics, weak microwave signals can be amplified with minimal added noise. For instance, artificial quantum systems based on superconducting circuits can amplify and detect single microwave patterns, although at millikelvin temperatures. Researchers can use natural quantum systems for low-noise microwave amplification via stimulated emission effects; however, they generate a higher noise at functionalities greater than 1 Kelvin.

In this new work, published in the journal Science Advances, Alexander Sherman and a team of scientists in chemistry at the Technical-Israel Institute of Technology, Haifa, used electron spins in diamond as a quantum microwave amplifier to function with quantum-limited internal noise above liquid nitrogen temperatures. The team reported details of the amplifier’s design, gain, bandwidth, saturation power and noise to facilitate hitherto unavailable applications in quantum science, engineering and physics.

For decades, physicists have been hunting for a quantum-gravity model that would unify quantum physics, the laws that govern the very small, and gravity. One major obstacle has been the difficulty in testing the predictions of candidate models experimentally. But some of the models predict an effect that can be probed in the lab: a very small violation of a fundamental quantum tenet called the Pauli exclusion principle, which determines, for instance, how electrons are arranged in atoms.

A project carried out at the INFN underground laboratories under the Gran Sasso mountains in Italy, has been searching for signs of radiation produced by such a violation in the form of atomic transitions forbidden by the Pauli exclusion principle.

In two papers appearing in the journals Physical Review Letters (published on September 19, 2022) and Physical Review D (accepted for publication on December 7, 2022) the team reports that no evidence of violation has been found, thus far, ruling out some quantum-gravity models.

Quantum telepathy, laser-based time crystals, a glow from empty space and an “unreal” universe—these are the most awesome (and awfully hard to understand) results from the subatomic realm we encountered in 2022.