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Category: quantum physics – Page 6

Physicists Perform “Quantum Surgery” To Fix Errors While Computing

Quantum computers are often described as a glimpse of a faster, more powerful future. The catch is that today’s devices are fragile in a way ordinary computers are not. Their biggest headache is decoherence, the gradual loss of the delicate quantum behavior that makes them useful in the first place. When decoherence sets in, it can trigger two common kinds of mistakes: bit flips and phase flips.

A bit flip is the more intuitive problem. A qubit that should represent ‘0’ can unexpectedly behave like ‘1’. A phase flip is stranger but just as damaging. Even if a qubit stays in a superposition, the relationship between its components can suddenly switch, turning a positive phase into a negative one and scrambling the computation.

Physicists discover what controls the speed of quantum time

From the article:

…in copper, the transition was extremely fast, taking about 26 attoseconds.

In the layered materials TiSe₂ and TiTe₂, the same process slowed to between 140 and 175 attoseconds. In CuTe, with its chain-like structure, the transition exceeded 200 attoseconds. These findings show that the atomic scale shape of a material strongly affects how quickly a quantum event unfolds, with lower symmetry structures leading to longer transition times.

Time may feel smooth and continuous, but at the quantum level it behaves very differently. Physicists have now found a way to measure how long ultrafast quantum events actually last, without relying on any external clock. By tracking subtle changes in electrons as they absorb light and escape a material, researchers discovered that these transitions are not instantaneous and that their duration depends strongly on the atomic structure of the material involved.

Seeing the Quantum Butterfly Effect

A combined experimental and theoretical study reveals the emergence of quantum chaos in a complex system, suggesting that it can be described with a universal theoretical framework.

Consider the following thought experiment: Take all the air molecules in a thunderstorm and evolve them backward in time for an hour, effectively rewinding a molecular movie. Then slightly perturb the velocity directions of a few molecules and evolve the system forward again to the current moment. Because such systems are chaotic, microscopic perturbations in the past will lead to dramatically different futures. This “butterfly effect” also occurs in quantum systems. To observe it, researchers measure a mathematical entity called the out-of-time-ordered correlator (OTOC). Loosely speaking, the OTOC measures how quickly a system “forgets” its initial state. Unfortunately, the OTOC is notoriously difficult to measure because it typically requires experimental protocols that implement an effective many-body time reversal.

Laser‑written glass chip pushes quantum communication toward practical deployment

As quantum computers continue to advance, many of today’s encryption systems face the risk of becoming obsolete. A powerful alternative—quantum cryptography—offers security based on the laws of physics instead of computational difficulty. But to turn quantum communication into a practical technology, researchers need compact and reliable devices that can decode fragile quantum states carried by light.

A new study from teams at the University of Padua, Politecnico di Milano, and the CNR Institute for Photonics and Nanotechnologies shows how this goal can be approached using a simple material: borosilicate glass. As reported in Advanced Photonics, their work demonstrates a high-performance quantum coherent receiver fabricated directly inside glass using femtosecond laser writing. The approach provides low optical loss, stable operation, and broad compatibility with existing fiber-optic infrastructure—key factors for scaling quantum technologies beyond the laboratory.

Muon Knight shift reveals the behavior of superconducting electron pairs

Quantum materials and superconductors are difficult enough to understand on their own. Unconventional superconductors, which cannot be explained within the framework of standard theory, take the enigma to an entirely new level. A typical example of unconventional superconductivity is strontium ruthenate, SRO214, the superconductive properties of which were discovered by a research team that included Yoshiteru Maeno, who is currently at the Toyota Riken—Kyoto University Research Center.

The findings are published in the journal Physical Review Letters.

Debate over SRO214’s superconducting nature.

Quantum dots reveal entropy production, a key measure of nanoscale energy dissipation

In order to build the computers and devices of tomorrow, we have to understand how they use energy today. That’s harder than it sounds. Memory storage, information processing, and energy use in these technologies involve constant energy flow—systems never settle into thermodynamic balance. To complicate things further, one of the most precise ways to study these processes starts at the smallest scale: the quantum domain.

New Stanford research published in Nature Physics combines theory, experimentation, and machine learning to quantify energy costs during a non-equilibrium process with ultrahigh sensitivity. Researchers used extremely small nanocrystals called quantum dots, which have unique light-emitting properties that arise from quantum effects at the nanoscale.

They measured the entropy production of quantum dots—a quantity that describes how reversible a microscopic process is, and encodes information about memory, information loss, and energy costs. Such measurements can determine the ultimate speed limits for a device or how efficient it can be.

A Simple Chemical Tweak Unlocks One of Quantum Computing’s Holy Grails

Even supercomputers can stall out on problems where nature refuses to play by everyday rules. Predicting how complex molecules behave or testing the strength of modern encryption can demand calculations that grow too quickly for classical hardware to keep up. Quantum computers are designed to tackle that kind of complexity, but only if engineers can build systems that run with extremely low error rates.

One of the most promising routes to that reliability involves a rare class of materials called topological superconductors. In plain terms, these are superconductors that also have built-in “protected” quantum behavior, which researchers hope could help shield delicate quantum information from noise. The catch is that making materials with these properties is famously difficult.

Uncovering hidden quantum landscapes

Imagine trying to read Braille while wearing thick winter gloves; you might feel the general shape of the book, but the story remains a mystery. For decades, this has been the reality for physicists trying to “feel” the invisible energy landscapes that govern how electrons move in quantum materials. Now, researchers at the Weizmann Institute of Science have taken the gloves off.

A single atomic defect acts as a new type of microscope to reveal the electrostatic potential landscape steering the behavior of electrons in quantum materials. (Image: Weizmann Institute of Science)

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