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Category: quantum physics – Page 82

Quantum entanglement distribution via uplink satellite channels

Significant work has been done to develop quantum satellites, which generate entangled pairs in space and distribute them to ground stations separated some distance away. The reverse “ uplink’’ case, where pairs are generated on the ground and swapped on the satellite using an optical Bell measurement, has not been seriously considered due to a prevailing assumption that it is practically infeasible. In this paper, we illustrate the feasibility of performing Discrete Variable photonic Bell measurements in space by conducting a detailed numerical analysis to estimate the channel efficiency and attainable pair fidelity for various satellite-station configurations. Our model accounts for a wide range of physical effects such as atmospheric effects, stray photons, and mode mismatch.

Physicists Take the Imaginary Numbers Out of Quantum Mechanics

A century ago, the strange behavior of atoms and elementary particles led physicists to formulate a new theory of nature. That theory, quantum mechanics, found immediate success, proving its worth with accurate calculations of hydrogen’s emission and absorption of light. There was, however, a snag. The central equation of quantum mechanics featured the imaginary number i, the square root of −1.

Physicists knew i was a mathematical fiction. Real physical quantities like mass and momentum never yield a negative amount when squared. Yet this unreal number that behaves as i2 = −1 seemed to sit at the heart of the quantum world.

After deriving the i-riddled equation — essentially the law of motion for quantum entities — Erwin Schrödinger expressed the hope that it would be replaced by an entirely real version. (“There is undoubtedly a certain crudeness at the moment” in the equation’s form, he wrote in 1926.) Schrödinger’s distaste notwithstanding, i stuck around, and new generations of physicists took up his equation without much concern.

Table salt enables new metallic nanotubes with potential for faster electronics

For the first time, researchers have made niobium sulfide metallic nanotubes with stable, predictable properties, a long-sought goal in advanced materials science. According to the international team, including a researcher at Penn State, that made the accomplishment, the new nanomaterial that could open the door to faster electronics, efficient electricity transport via superconductor wires and even future quantum computers was made possible with a surprising ingredient: table salt.

They published their research in ACS Nano.

Nanotubes are structures so small that thousands of them could fit across the width of a human hair. The tiny hollow cylinders are made by rolling up sheets of atoms; nanotubes have an unusual size and shape that can cause them to behave very differently from 3D, or bulk, materials.

Single organic molecule triggers Kondo effect in molecular-scale ‘Kondo box’

A research group led by Prof. Li Xiangyang from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, has made a new discovery: a single organic molecule can induce the Kondo effect in a magnetic atom, challenging the long-standing belief that this quantum phenomenon requires a vast sea of metallic electrons.

The research results were published in Physical Review Letters.

The Kondo effect is a quantum many-body phenomenon where conduction electrons in a metal collectively screen the magnetic moment of a localized impurity atom. It has been helping to explain strongly correlated electron behavior and inspiring advances in nanoscience, , and quantum information research.

Quantum “Pinball” State of Matter: Electrons That Conduct and Insulate at the Same Time

Physicists at Florida State University (FSU) have uncovered a fascinating new phase of matter — a “ quantum pinball state” in which electrons act both as conductors and insulators at the same time. In this bizarre quantum regime, some electrons freeze into a rigid crystalline lattice while others move freely around them, much like balls ricocheting around fixed pins in a pinball machine. The discovery offers a new perspective on how quantum materials behave and could pave the way for breakthroughs in quantum computing, spintronics, and superconductivity.

The research, published in npj Quantum Materials, was led by Dr. Aman Kumar, Prof. Hitesh Changlani, and Prof. Cyprian Lewandowski of FSU’s National High Magnetic Field Laboratory. Their study explores how electrons in a two-dimensional “moiré lattice” can transition between solid-like and liquid-like states under certain conditions, forming what physicists call a generalized Wigner crystal.

How quantum computers can aid the search for room-temperature superconductors

For the first time, a quantum computer has successfully measured pairing correlations (quantum signals that show electrons teaming up in pairs), which is essential to helping scientists find one of the holy grails of physics—superconductors that work at room temperature.

Superconductors are materials that can conduct electricity with zero resistance, meaning no energy is lost as heat. To work, they need to be cooled to extremely low temperatures, which makes them expensive and impractical for widespread use. Physicists have been trying to tweak their structure to make them work at , and many believe that understanding and manipulating electron-pairing correlations are key to that breakthrough.

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