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A series of buzzing, bee-like “loop-currents” could explain a recently discovered, never-before-seen phenomenon in a type of quantum material. The findings from researchers at the University of Colorado Boulder may one day help engineers to develop new kinds of devices, such as quantum sensors or the quantum equivalent of computer memory storage devices.

The quantum material in question is known by the chemical formula Mn₃Si₂Te₆. But you could also call it “honeycomb” because its manganese and tellurium atoms form a network of interlocking octahedra that look like the cells in a beehive.

Physicist Gang Cao and his colleagues at CU Boulder synthesized this molecular beehive in their lab in 2020, and they were in for a surprise: Under most circumstances, the material behaved a lot like an insulator. In other words, it didn’t allow electric currents to pass through it easily. When they exposed the honeycomb to magnetic fields in a certain way, however, it suddenly became millions of times less resistant to currents. It was almost as if the material had morphed from rubber into metal.

Researchers demonstrate room-temperature spin transfer across an interface between an iron-based ferromagnet and a semiconductor, opening a route to creating novel spintronic devices.

A mechanism for preventing destructive instabilities in magnetically confined plasmas provides a new way for scientists to operate future nuclear-fusion reactors.

All magnetically confined plasmas naturally develop instabilities, regions where small perturbations grow rapidly [1]. Scientists have been looking for ways to prevent instabilities in a tokamak—a leading candidate for a fusion reactor—because the instabilities can cause substantial damage to the tokamak’s walls. Now Georg Harrer at the Vienna University of Technology and his colleagues have shown how these destructive instabilities can be avoided by adjusting the properties of the plasma and its confining magnetic field [2]. The researchers’ findings offer a fresh approach to running future fusion reactors.

A tokamak uses a powerful magnetic field to confine fusion fuel in the form of a plasma (a highly ionized gas) that is shaped like a ring donut. Instabilities that originate at the plasma edge (the “glaze” of the donut) are called edge-localized modes (ELMs) [3]. ELMs transport heat and particles along magnetic-field lines, moving them from the well-confined plasma core (the “filling” of the donut) to the divertor—a region of the tokamak’s walls. ELMs come in various sizes and frequencies (repetition rates). Their size, expressed as a percentage of the energy stored in the plasma core, strongly influences how much heat and how many particles will be deposited by each ELM in the divertor.

Circa 2014 face_with_colon_three

A liquid hard drive containing a suspension of nanoparticles could be used to store impressive amounts of data: 1 terabyte per tablespoon.

Researchers from the University of Michigan and New York University have been simulating wet information storage techniques which uses clusters of nanoparticles suspended in liquid. These clusters of particles can store more data than conventional computer bits which have just two storage states: 0 and 1. The clusters of particles work a bit like Rubik’s Cubes to reconfigure in different ways to represent different storage states. A 12-particle memory cluster connected to a central sphere can have almost eight million unique states, which is equivalent to 2.86 bytes of data.

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Recently published research pushes the boundaries of key concepts in quantum mechanics. Studies from two different teams used tiny drums to show that quantum entanglement, an effect generally linked to subatomic particles, can also be applied to much larger macroscopic systems. One of the teams also claims to have found a way to evade the Heisenberg uncertainty principle.

One question that the scientists were hoping to answer pertained to whether larger systems can exhibit quantum entanglement in the same way as microscopic ones. Quantum mechanics proposes that two objects can become “entangled,” whereby the properties of one object, such as position or velocity, can become connected to those of the other.

A Q&A with Caltech alumnus John Clauser on his first experimental proof of quantum entanglement.

When scientists, including Albert Einstein and Erwin Schrödinger, first discovered the phenomenon of entanglement in the 1930s, they were perplexed. Disturbingly, entanglement required two separated particles to remain connected without being in direct contact. In fact, Einstein famously called entanglement “spooky action at a distance,” because the particles seemed to be communicating faster than the speed of light.

Born on December 1, 1942, John Francis Clauser is an American theoretical and experimental physicist known for contributions to the foundations of quantum mechanics, in particular the Clauser–Horne–Shimony–Holt inequality. Clauser was awarded the 2022 Nobel Prize in Physics, jointly with Alain Aspect and Anton Zeilinger “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science.”

The proton is a composite particle made up of fundamental building blocks of quarks and gluons. These components and their interactions determine the proton’s structure, including its electrical charges and currents. This structure deforms when exposed to external electric and magnetic (EM) fields, a phenomenon known as polarizability. The EM polarizabilities are a measure of the stiffness against the deformation induced by EM fields. By measuring the EM polarizabilities, scientists learn about the internal structure of the proton.

This knowledge helps to validate scientific understanding of how nucleons (protons and neutrons) form by comparing the results to theoretical descriptions of gamma-ray scattering from nucleons. Scientists call this scattering process nucleon Compton scattering.

When scientists examine the proton at a distance and scale where EM responses dominate, they can determine values of EM polarizabilities with high precision. To do so, they use the theoretical frame of Effective Field Theories (EFTs). The EFTs hold the promise of matching the description of the nucleon structure at low energies to the current theory of the strong nuclear force, called quantum chromodynamics (QCD). In this research, scientists validated EFTs using proton Compton scattering. This approach also validated the framework and methodology that underlie EFTs.

Today, one of the biggest paradoxes in the universe threatens to unravel modern science: the black hole information paradox. Every object in the universe is composed of particles with unique quantum properties and even if an object is destroyed, its quantum information is never permanently deleted. But what happens to that information when an object enters a black hole? Fabio Pacucci investigates. [Directed by Artrake Studio, narrated by Addison Anderson, music by WORKPLAYWORK / Cem Misirlioglu].

Photons, particles that represent a quantum of light, have shown great potential for the development of new quantum technologies. More specifically, physicists have been exploring the possibility of creating photonic qubits (quantum units of information) that can be transmitted over long distances using photons.

Despite some promising results, several obstacles still need to be overcome before photonic qubits can be successfully implemented on a large-scale. For instance, photons are known to be susceptible to propagation loss (i.e., a loss of energy, radiation, or signals as it travels from one point to another) and do not interact with one another.

Researchers at University of Copenhagen in Denmark, Instituto de Física Fundamental IFF-CSIC in Spain, and Ruhr-Universität Bochum in Germany have recently devised a strategy that could help to overcome one of these challenges, namely the lack of photon-photon interactions. Their method, presented in a paper published in Nature Physics, could eventually aid the development of more sophisticated quantum devices.