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Category: quantum physics – Page 19

Electrons Mysteriously Slow to a Crawl Inside This Magnetic Material

Inside an unusual magnetic material, electrons are doing something physicists did not expect: slowing to a near crawl while moving together in quantum lockstep.

A team at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) found that electrons in Fe5GeTe2 can enter a charge-ordered state where they move collectively, remain quantum coherent, and travel far more slowly than expected.

The result could force scientists to rethink how magnetism works in this material. It may also offer a new way to store information by switching between distinct electronic and magnetic states.

Thermal detection of single photons using Dirac fermions

Single photon detectors are essential for various quantum and imaging applications. Here, the authors report graphene bolometers able to detect single near-infrared photons at temperatures up to 1.2 K with intrinsic quantum efficiency up to 87%, dark count  < 1 per second and effective noise equivalent power down to 2 × 10−22 W/ $$\sqrt{{{{\rm{Hz}}}}}$$ Hz.

Long-sought Zhang-Rice singlet visualized directly in cuprate superconductor

Superconductors are materials that conduct electricity with zero electrical resistance below specific temperatures. Most of these materials become superconducting at very low temperatures, but some also exhibit superconductivity at higher temperatures.

Superconductors have proved advantageous for the development of numerous technologies, ranging from medical imaging instruments to particle accelerators, nuclear reactors, power transmission lines and quantum computers. While past studies have shed light on the physical underpinnings of conventional, low-temperature superconductivity, the processes contributing to high-temperature superconductivity remain poorly understood.

Researchers at Tsinghua University and the Chinese Academy of Sciences recently carried out a study aimed at better understanding the physical processes that give rise to superconductivity in hole-doped Ca₂CuO₂Cl₂ (CCOC), an unconventional cuprate superconductor.

Spontaneous magnons synchronize with external signals at room temperature

Signals ride on waves of one kind or another: light, sound, radio. But new carriers are needed to relay information in next-generation devices. Disturbances or waves in magnetic materials called magnons could be an efficient option—if scientists can tame them.

A team led by researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of Illinois Urbana-Champaign (U. of I.) has developed a method to generate spontaneous magnons in a material called yttrium iron garnet (YIG) that can be tuned to an external signal.

The results, reported in Nature Communications, establish a pathway toward controllable magnons that are relevant for next-generation microelectronics, wireless communication and quantum information processing.

Quantum advantage reassessed: More realistic benchmarks for quantum algorithms

Quantum advantage refers to the point at which a quantum computer solves a clearly defined task faster or more efficiently than any classical computer—or makes it solvable in the first place. For many practical applications, this has not yet been demonstrated. Research therefore relies heavily on theoretical models and simulations to explore where and under what conditions such an advantage may realistically be achieved in the future.

Quantum simulation is considered a promising path toward genuine quantum advantage.

However, many existing approaches in quantum chemistry rely on simplifying assumptions: They describe molecules as closed systems perfectly isolated from their environment, model only unitary dynamics and focus on calculating ground states within the Born-Oppenheimer approximation. In nature, none of these assumptions fully hold.

MIT Physicists Zapped a Quantum Crystal With Lasers — and Discovered Something Surprising

MIT physicists have uncovered a surprising split in the behavior of electrons inside a quantum material: two nearly identical electronic patterns rebuild themselves in fundamentally different ways.

Electrons inside a solid do not always behave like independent particles. Under the right conditions, enormous numbers of them can reorganize together, producing entirely new states of matter with properties that the original material did not appear to possess.

MIT physicists have now watched that collective reorganization unfold in unusual detail. Their experiments reveal that two electronic phases occupying the same quantum material can form through fundamentally different mechanisms, even though both involve the same underlying type of electron order.

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