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Category: quantum physics – Page 8

Using entanglement to test whether gravity is quantum just got more complicated

Unifying gravity and quantum theory remains a significant goal in modern physics. Despite the success in unifying all other fundamental interactions (electromagnetism, strong force and weak force) with quantum mechanics and many attempts at explaining a “quantum gravity,” scientists are still coming up short. Still, some believe we are getting closer to determining whether these two theories can be combined or whether they are truly incompatible.

A major contender for proving or disproving whether gravity is quantum is Richard Feynman’s proposed experiment to test if gravity can entangle two massive objects. In theory, such entanglement would indicate quantum behavior. While it was not actually feasible to do this experiment in 1957, when Feynman came up with the idea, new scientific advances are bringing it closer to reality.

However, a new study, published in Nature, claims that it’s a little more complicated than this. The researchers involved in the study determined, through their calculations, that entanglement is not necessarily evidence of quantum gravity—and that classical gravity can generate this entanglement in some cases too.

Google claims its latest quantum algorithm can outperform supercomputers on a real-world task

Researchers from Google Quantum AI report that their quantum processor, Willow, ran an algorithm for a quantum computer that solved a complex physics problem thousands of times faster than the world’s most powerful classical supercomputers. If verified, this would be one of the first demonstrations of practical quantum advantage, in which a quantum computer solves a real-world problem faster and more accurately than a classical computer.

In a new paper published in the journal Nature, the researchers provided details on how their algorithm, called Quantum Echoes, measured the complex behavior of particles in highly entangled . These are systems in which multiple particles are linked so that they share the same fate even when physically separated. If you measure the property of one particle, you instantly know something about the others. This linkage makes the overall system so complex that it is difficult to model on ordinary computers.

The Quantum Echoes algorithm uses a concept called an Out-of-Time-Order Correlator (OTOC), which measures how quickly information spreads and scrambles in a quantum system. The researchers chose this specific measurement because, as they state in the paper, “OTOCs have quantum interference effects that endow them with a high sensitivity to details of the quantum dynamics and, for OTOC, also high levels of classical simulation complexity. As such, OTOCs are viable candidates for realizing practical quantum advantage.”

Record-breaking quantum key distribution transmission distance achieved alongside classical channels

Quantum key distribution (QKD) harnesses the power of quantum mechanics to securely transmit confidential information. When an outside source eavesdrops on a QKD transmission, the quantum states are affected. This dependably alerts the receiver and sender that the transmission is no longer secure.

Unfortunately, there have thus far been limitations in implementing QKD technology. Telecom networks require QKD and classical data to share fiber infrastructure to reduce costs enough to be feasible on a large scale and classical data channels introduce noise that limits the distance and performance of QKD transmissions. Many solutions have been proposed and tested, such as extra filtering or dedicated wavelengths, but these still complicate integration into existing telecom networks.

Now, researchers from Denmark and the Czech Republic may have a better solution that, when tested, broke the record for the longest transmission achieved with QKD and classical data.

https://lnkd.in/gUDFq8KF Explicit solution of Navier Stokes Equation A millennium problem! can we prove that fluid motion always stays smooth, or can it blow up into chaos?

Here’s the equation that rules all fluids: ρ (∂u/∂t + (u·∇)u) = −∇p + μ∇²u + f What it means: — u: velocity field (how the fluid moves) — p: pressure — μ: viscosity (internal friction) — ρ: density — f: external forces (like gravity) Instead of solving the velocity u directly, he treats the fluid like a symphony of interacting notes: φ(x, t) = ∫ d³k [ aₖ e^(-iωt + ik·x) + aₖ† e^(iωt — ik·x) ] Each aₖ and aₖ† represent creation and annihilation operators — the conductors of the quantum orchestra of sound. 🎵 Analogy: Fluid as a Symphony Imagine a calm pond. Every ripple is a gentle musical note. Now drop many stones — the ripples overlap, collide, and amplify. That’s turbulence.

Supersolid spins into synchrony, unlocking quantum insights

A supersolid is a paradoxical state of matter—it is rigid like a crystal but flows without friction like a superfluid. This exotic form of quantum matter has only recently been realized in dipolar quantum gases.

Researchers led by Francesca Ferlaino set out to explore how the solid and superfluid properties of a interact, particularly under rotation. The study is published in Nature Physics.

In their experiments, they rotated a supersolid quantum gas using a carefully controlled magnetic field and observed a striking phenomenon.

Common crystal proves ideal for low-temperature light technology

Superconductivity and quantum computing are two fields that have seeped from theoretical circles into popular consciousness. The 2025 Nobel Prize in physics was awarded for work in superconducting quantum circuits that could drive ultra-powerful computers. But what may be less well known is that these promising technologies are often possible only at cryogenic temperatures—near absolute zero. Unfortunately, few materials can handle such extremes. Their cherished physical properties disappear when the chill is on.

In a new paper published in Science, however, a team of engineers at Stanford University spotlights a promising material—strontium titanate, or STO for short—where the optical and mechanical characteristics do not decline at extreme low temperatures, but actually get significantly better, outperforming existing materials by a wide margin.

They believe these findings suggest that STO could become the building block for new light-based and mechanical cryogenic devices that push , , and other fields to the next level.

Simulations hint at new strongly correlated states of matter in ultracold polar molecules

Bose-Einstein condensates (BECs) are fascinating states of matter that emerge when atoms or molecules are cooled to extremely low temperatures just slightly above absolute zero (0 K). In 2023, physicists at Columbia University realized BECs comprised of ultracold molecules for the very first time.

Building on their work, another research group at TU Wien and the Vienna Center for Quantum Science and Technology recently set out to investigate the behavior of these ultracold dipolar molecules, while also exploring the possibility that they could spontaneously organize themselves into new forms of matter. Their findings, published in Physical Review Letters, suggest that new correlated states could emerge in ultracold polar molecules, showing that these states could be probed in future experiments.

“BECs of ultracold polar molecules were a decade-long goal, but have only been realized experimentally very recently,” Matteo Ciardi, co-author of the paper, told Phys.org.

Microscopic ‘ocean’ on a chip reveals new nonlinear wave behavior

University of Queensland researchers have created a microscopic “ocean” on a silicon chip to miniaturize the study of wave dynamics. The device, made at UQ’s School of Mathematics and Physics, uses a layer of superfluid helium only a few millionths of a millimeter thick on a chip smaller than a grain of rice.

The work is published in the journal Science.

Dr. Christopher Baker said it was the world’s smallest wave tank, with the quantum properties of superfluid helium allowing it to flow without resistance, unlike classical fluids such as water, which become immobilized by viscosity at such small scales.

Heterostructure-Engineered Semiconductor Quantum Dots toward Photocatalyzed-Redox Cooperative Coupling Reaction

Semiconductor quantum dots have been emerging as one of the most ideal materials for artificial photosynthesis. Here, we report the assembled ZnS-CdS hybrid heterostructure for efficient coupling cooperative redox catalysis toward the oxidation of 1-phenylethanol to acetophenone/2,3-diphenyl-2,3-butanediol (pinacol) integrated with the reduction of protons to H2. The strong interaction and typical type-I band-position alignment between CdS quantum dots and ZnS quantum dots result in efficient separation and transfer of electron-hole pairs, thus distinctly enhancing the coupled photocatalyzed-redox activity and stability. The optimal ZnS-CdS hybrid also delivers a superior performance for various aromatic alcohol coupling photoredox reaction, and the ratio of electrons and holes consumed in such redox reaction is close to 1.0, indicating a high atom economy of cooperative coupling catalysis. In addition, by recycling the scattered light in the near field of a SiO2 sphere, the SiO2-supported ZnS-CdS (denoted as ZnS-CdS/SiO2) catalyst can further achieve a 3.5-fold higher yield than ZnS-CdS hybrid. Mechanistic research clarifies that the oxidation of 1-phenylethanol proceeds through the pivotal radical intermediates of • C(CH3)(OH)Ph. This work is expected to promote the rational design of semiconductor quantum dots-based heterostructured catalysts for coupling photoredox catalysis in organic synthesis and clean fuels production.

Copyright © 2023 Lin-Xing Zhang et al.

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Hydrogen atom

A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral hydrogen atom contains a single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force. Atomic hydrogen constitutes about 75% of the baryonic mass of the universe. [ 1 ]

In everyday life on Earth, isolated hydrogen atoms (called “atomic hydrogen”) are extremely rare. Instead, a hydrogen atom tends to combine with other atoms in compounds, or with another hydrogen atom to form ordinary (diatomic) hydrogen gas, H2. “Atomic hydrogen” and “hydrogen atom” in ordinary English use have overlapping, yet distinct, meanings. For example, a water molecule contains two hydrogen atoms, but does not contain atomic hydrogen (which would refer to isolated hydrogen atoms).

Atomic spectroscopy shows that there is a discrete infinite set of states in which a hydrogen (or any) atom can exist, contrary to the predictions of classical physics. Attempts to develop a theoretical understanding of the states of the hydrogen atom have been important to the history of quantum mechanics, since all other atoms can be roughly understood by knowing in detail about this simplest atomic structure.

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