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First-principles simulations reveal quantum entanglement in molecular polariton dynamics

This is what fun looks like for a particular set of theoretical chemists driven to solve extremely difficult problems: Deciding whether the electromagnetic fields in molecular polaritons should be treated classically or quantum mechanically.

Graduate student Millan Welman of the Hammes-Schiffer Group is first author on a new paper that presents a hierarchy of first principles simulations of the dynamics of molecular polaritons. The research is published in the Journal of Chemical Theory and Computation.

Originally 67 pages long, the paper is dense with von Neumann equations and power spectra. It explores dynamics on both electronic and vibrational energy scales. It makes use of time-dependent density functional theory (DFT) in both its conventional and nuclear-electronic orbital (NEO) forms. It spans semiclassical, mean-field-quantum, and full-quantum approaches to simulate dynamics.

Electrons that act like photons reveal a quantum secret

Quantum materials, defined by their photon-like electrons, are opening new frontiers in material science. Researchers have synthesized organic compounds that display a universal magnetic behavior tied to a distinctive feature in their band structures called linear band dispersion. This discovery not only deepens the theoretical understanding of quantum systems but also points toward revolutionary applications in next-generation information and communication technologies that conventional materials cannot achieve.

British Startup Installs New York City’s First Quantum Computer

A British startup has installed New York City’s first quantum computer at a data center in Manhattan.

Oxford Quantum Circuits has placed the system at a data center run by Digital Realty Trust in the Google building in Chelsea, billing the technology to customers of the site as a means of running artificial intelligence programs faster and more efficiently. Oxford Quantum Chief Executive Officer Gerald Mullally said he expects his firm to spend tens of millions of dollars over three to five years, in part to buy Nvidia Corp. chips to integrate into it. He declined to provide the exact costs of the computer.

Measuring the quantum W state: Seeing a trio of entangled photons in one go

The concept of quantum entanglement is emblematic of the gap between classical and quantum physics. Referring to a situation in which it is impossible to describe the physics of each photon separately, this key characteristic of quantum mechanics defies the classical expectation that each particle should have a reality of its own, which gravely concerned Einstein.

Understanding the potential of this concept is essential for the realization of powerful new quantum technologies.

Developing such technologies will require the ability to freely generate a multi– quantum , and then to efficiently identify what kind of entangled state is present. However, when performing conventional quantum tomography, a method commonly used for state estimation, the number of measurements required grows exponentially with the number of photons, posing a significant data collection problem.

New quantum sensors can withstand extreme pressure

The world of quantum physics is already mysterious, but what happens when that strange realm of subatomic particles is put under immense pressure? Observing quantum effects under pressure has proven difficult for a simple reason: Designing sensors that can withstand extreme forces is challenging.

In a significant advance, a team led by physicists at WashU has created in an unbreakable sheet of crystallized . The sensors can measure stress and magnetism in materials under pressure that exceeds 30,000 times the pressure of the atmosphere.

“We’re the first ones to develop this sort of high-pressure sensor,” said Chong Zu, an assistant professor of physics in Arts & Sciences and a member of Washington University in St. Louis’ Center for Quantum Leaps. “It could have a wide range of applications in fields ranging from quantum technology, , to astronomy and geology.”

Synthetic magnetic fields steer light on a chip for faster communications

Electrons in a magnetic field can display striking behaviors, from the formation of discrete energy levels to the quantum Hall effect. These discoveries have shaped our understanding of quantum materials and topological phases of matter. Light, however, is made of neutral particles and does not naturally respond to magnetic fields in the same way. This has limited the ability of researchers to reproduce such effects in optical systems, particularly at the high frequencies used in modern communications.

To address this challenge, researchers from Shanghai Jiao Tong University and Sun Yat-Sen University have developed a method for generating pseudomagnetic fields—synthetic fields that mimic the influence of real magnetic fields—inside nanostructured materials known as photonic crystals.

Unlike previous demonstrations, which focused on specific effects such as photonic Landau levels, the new approach allows arbitrary control of how light flows within the material. Their research is published in Advanced Photonics.

Microscopes can now watch materials go quantum with liquid helium

A new specimen holder gives scientists more control over ultra-cold temperatures, enabling the study of how materials acquire properties useful in quantum computers.

Scientists can now reliably chill specimens near absolute zero for over 10 hours while taking images resolved to the level of individual atoms with an . The new capability comes from a liquid-helium-cooled sample holder designed by a team of scientists and engineers at the University of Michigan and Harvard University.

Conventional instruments can usually maintain such an extreme temperature, about-423 degrees Fahrenheit or 20 degrees above absolute zero, for a few minutes, capping out at a few hours. But longer periods of time are needed to take atomic-resolution images of candidate materials for advanced technologies.

Mathematical ‘sum of zeros’ trick exposes topological magnetization in quantum materials

A new study addresses a foundational problem in the theory of driven quantum matter by extending the Středa formula to non-equilibrium regimes. It demonstrates that a superficially trivial “sum of zeros” encodes a universal, quantized magnetic response—one that is intrinsically topological and uniquely emergent under non-equilibrium driving conditions.

Imagine a strange material being rhythmically pushed—tapped again and again by invisible hands. These are periodically driven , or Floquet systems, where energy is no longer conserved in the usual sense. Instead, physicists speak of quasienergy—a looping spectrum with no clear start or end.

When scientists measure how such a system responds to a magnetic field, every single contribution seems to vanish—like adding an infinite list of zeros. And yet, the total stubbornly comes out finite, quantized, and very real.

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