Understanding the possible quantum-driven behaviors of biological systems could aid in treating injuries or in developing cures for diseases, but research in the field has been pushed to the sidelines. It’s time for that to change.
A quantum photonic device can perform some real-world tasks more efficiently than classical computers.
Experiments probing quasiparticles in semiconductor microcavities offer unprecedented insights into the dynamics of quantum fluids of light.
Superfluidity [1, 2], the ability of a fluid to flow without friction, isn’t restricted to systems described by hydrodynamics. Over a decade ago, optics researchers started to take an interest in superfluids and other quantum fluids [3], driven by the realization that light propagating in a nonlinear medium can exhibit quantum hydrodynamics features [4]. Two platforms emerged for the study of these “fluids of light”: semiconductor microcavities in which photons are confined [5] and propagating geometries in which photons travel in a bulk medium [6–8]. Both configurations allow photons to acquire an effective mass and experience an effective mutual interaction—properties that can lead them to collectively behave as a quantum fluid.
Physicists have discovered “stacked pancakes of liquid magnetism” that may account for the strange electronic behavior of some layered helical magnets.
The materials in the study are magnetic at cold temperatures and become nonmagnetic as they thaw. Experimental physicist Makariy Tanatar of Ames National Laboratory at Iowa State University noticed perplexing electronic behavior in layered helimagnetic crystals and brought the mystery to the attention of Rice theoretical physicist Andriy Nevidomskyy, who worked with Tanatar and former Rice graduate student Matthew Butcher to create a computational model that simulated the quantum states of atoms and electrons in the layered materials.
Magnetic materials undergo a “thawing” transition as they warm up and become nonmagnetic. The researchers ran thousands of Monte Carlo computer simulations of this transition in helimagnets and observed how the magnetic dipoles of atoms inside the material arranged themselves during the thaw. Their results were published in a recent study in Physical Review Letters.
A group of researchers led by Andreas Wallraff, Professor of Solid State Physics at ETH Zurich, has performed a loophole-free Bell test to disprove the concept of “local causality” formulated by Albert Einstein in response to quantum mechanics.
By showing that quantum mechanical objects that are far apart can be much more strongly correlated with each other than is possible in conventional systems, the researchers have provided further confirmation for quantum mechanics. What’s special about this experiment is that the researchers were able for the first time to perform it using superconducting circuits, which are considered to be promising candidates for building powerful quantum computers.
A Bell test is based on an experimental setup that was initially devised as a thought experiment by British physicist John Bell in the 1960s. Bell wanted to settle a question that the greats of physics had already argued about in the 1930s: Are the predictions of quantum mechanics, which run completely counter to everyday intuition, correct, or do the conventional concepts of causality also apply in the atomic microcosm, as Albert Einstein believed?
In a result decades in the making, Los Alamos scientists have achieved light amplification with electrically driven devices based on solution-cast semiconductor nanocrystals—tiny specs of semiconductor matter made via chemical synthesis and often called colloidal quantum dots.
This demonstration, reported in the journal Nature, opens the door to a completely new class of electrically pumped lasing devices—highly flexible, solution-processable laser diodes that can be prepared on any crystalline or non-crystalline substrate without the need for sophisticated vacuum-based growth techniques or a highly controlled clean-room environment.
“The capabilities to attain light amplification with electrically driven colloidal quantum dots have emerged from decades of our previous research into syntheses of nanocrystals, their photophysical properties and optical and electrical design of quantum dot devices,” said Victor Klimov, Laboratory Fellow and leader of the quantum dot research initiative.
Quantum dots in semiconductors such as silicon or gallium arsenide have long been considered hot candidates for hosting quantum bits in future quantum processors. Scientists at Forschungszentrum Jülich and RWTH Aachen University have now shown that bilayer graphene has even more to offer here than other materials.
The double quantum dots they have created are characterized by a nearly perfect electron-hole-symmetry that allows a robust read-out mechanism—one of the necessary criteria for quantum computing. The results were published in Nature.
The development of robust semiconductor spin qubits could help the realization of large-scale quantum computers in the future. However, current quantum dot based qubit systems are still in their infancy. In 2022, researchers at QuTech in the Netherlands were able to create 6 silicon-based spin qubits for the first time. With graphene, there is still a long way to go. The material, which was first isolated in 2004, is highly attractive to many scientists. But the realization of the first quantum bit has yet to come.
In two landmark experiments, researchers used quantum processors to engineer exotic particles that have captivated physicists for decades. The work is a step toward crash-proof quantum computers.
It is often desirable to restrict flows—whether of sound, electricity, or heat—to one direction, but naturally occurring systems almost never allow this. However, unidirectional flow can indeed be engineered under certain conditions, and the resulting systems are said to exhibit chiral behavior.
The concept of chirality is traditionally limited to single direction flows in one dimension. In 2021, however, researchers working with Taylor Hughes, a professor of physics at the University of Illinois Urbana-Champaign, introduced a theoretical extension that can account for more intricate chiral flows in two dimensions.
Now, a team led by Hughes and Gaurav Bahl, a UIUC professor of mechanical science & engineering, has experimentally realized this extension. As the researchers reported in Nature Communications, they constructed a topological circuit network, a system of electronics that simulates the microscopic behavior of quantum materials, to explore the entirely new behaviors predicted by this extended, or higher-rank chirality.
