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Category: quantum physics – Page 12

Record-breaking photons at telecom wavelengths—on demand

A team of researchers from the University of Stuttgart and the Julius-Maximilians-Universität Würzburg led by Prof. Stefanie Barz (University of Stuttgart) has demonstrated a source of single photons that combines on-demand operation with record-high photon quality in the telecommunications C-band—a key step toward scalable photonic quantum computation and quantum communication. “The lack of a high-quality on-demand C-band photon source has been a major problem in quantum optics laboratories for over a decade—our new technology now removes this obstacle,” says Prof. Stefanie Barz.

In everyday life, distinguishing features may often be desirable. Few want to be exactly like everyone else. When it comes to quantum technologies, however, complete indistinguishability is the name of the game. Quantum particles such as photons that are identical in all their properties can interfere with each other—much as in noise-canceling headphones, where sound waves that are precisely inverted copies of the incoming noise cancel out the background.

When identical photons are made to act in synchrony, then the probability that certain measurement outcomes occur can be either boosted or decreased. Such quantum effects give rise to powerful new phenomena that lie at the heart of emerging technologies such as quantum computing and quantum networking. For these technologies to become feasible, high-quality interference between photons is essential.

Quantum mechanical effects help overcome a fundamental limitation of optical microscopy

Researchers from Regensburg and Birmingham have overcome a fundamental limitation of optical microscopy. With the help of quantum mechanical effects, they succeeded for the first time in performing optical measurements with atomic resolution. Their work is published in the journal Nano Letters.

From smartphone cameras to space telescopes, the desire to see ever finer detail has driven technological progress. Yet as we probe smaller and smaller length scales, we encounter a fundamental boundary set by light itself. Because light behaves as a wave, it cannot be focused arbitrarily sharply due to an effect called diffraction. As a result, conventional optical microscopes are unable to resolve structures much smaller than the wavelength of light, placing the very building blocks of matter beyond direct optical observation.

Now, researchers at the Regensburg Center for Ultrafast Nanoscopy, together with colleagues at the University of Birmingham, have found a novel way to overcome this limitation. Using standard continuous-wave lasers, they have achieved optical measurements at distances comparable to the spacing between individual atoms.

Random driving on a 78-qubit processor reveals controllable prethermal plateau

Time-dependent driving has become a powerful tool for creating novel nonequilibrium phases such as discrete time crystals and Floquet topological phases, which do not exist in static systems. Breaking continuous time-translation symmetry typically leads to the outcome that driven quantum systems absorb energy and eventually heat up toward a featureless infinite-temperature state, where coherent structure is lost.

Understanding how fast this heating process occurs and whether it can be controlled has become a challenge in nonequilibrium physics. High-frequency periodic driving is known to delay heating, but much less is known about heating dynamics under more general, non-periodic driving protocols.

Laser Light Rewrites Magnetism in Breakthrough Quantum Material

Researchers at the University of Basel and ETH Zurich have found a way to flip the magnetic polarity of an unusual ferromagnet using a laser beam. If the approach can be refined and scaled, it points toward electronic components that could be reconfigured with light instead of being permanently fixed.

A ferromagnet acts like it has a built-in internal agreement. Inside the material, enormous numbers of electrons behave like tiny bar magnets because of their spins. When those spins line up, their individual magnetic fields add together, producing the familiar strength that makes a compass needle settle in a direction or lets a refrigerator magnet cling to a door.

That orderly alignment is not automatic, because heat constantly shakes the system. Ferromagnetism appears only when the interactions that encourage alignment win out over thermal motion, which happens below a critical temperature (often called the Curie temperature).

Physicists Watch a Superfluid Freeze, Revealing a Strange New Quantum State of Matter

Physicists have observed a strange new quantum phase in a graphene-based system, where a superfluid appears to freeze into a solid-like state. Cooling usually pushes matter through a simple sequence. A gas condenses into a liquid, and with further cooling the liquid locks into a solid. Helium hel

2D discrete time crystals realized on a quantum computer for the first time

Physical systems become inherently more complicated and difficult to produce in a lab as the number of dimensions they exist in increases—even more so in quantum systems. While discrete time crystals (DTCs) had been previously demonstrated in one dimension, two-dimensional DTCs were known to exist only theoretically. But now, a new study, published in Nature Communications, has demonstrated the existence of a DTC in a two-dimensional system using a 144-qubit quantum processor.

Like regular crystalline materials, DTCs exhibit a kind of periodicity. However, the crystalline materials most people are familiar with have a periodically repeating structure in space, while the particles in DTCs exhibit periodic motion over time. They represent a phase of matter that breaks time-translation symmetry under a periodic driving force and cannot experience an equilibrium state.

“Consequently, local observables exhibit oscillations with a period that is a multiple of the driving frequency, persisting indefinitely in perfectly isolated systems. This subharmonic response represents a spontaneous breaking of discrete time-translation symmetry, analogous to the breaking of continuous spatial symmetry in conventional solid-state crystals,” the authors of the new study explain.

Physicists Discover a New Way To Connect Qubits Using Crystal Imperfections

A new study suggests that crystal defects in diamond may hold the key to scalable quantum interconnects. Connecting large numbers of quantum bits (qubits) into a working technology remains one of the biggest obstacles facing quantum computing. Qubits are extraordinarily sensitive, and even small di

Stephen Wolfram: computation is the universe’s OS

Mathematica creator Stephen Wolfram has spent nearly 50 years arguing that simple computational rules underlie everything from animal patterns to the laws of physics. In his 2023 TED talk, he makes the case that computation isn’t just a useful way to model the world — it’s the fundamental operating system of reality itself.

Wolfram introduces “the ruliad,” an abstract concept encompassing all possible computational processes. Space and matter, he argues, consist of discrete elements governed by simple rules. Gravity and quantum mechanics emerge from the same computational framework. The laws of physics themselves are observer-dependent, arising from our limited perspective within an infinite computational structure.

On AI, Wolfram sees large language models as demonstrating deep connections between semantic grammar and computational thinking. The Wolfram Language, he claims, bridges human conceptualization and computational power, letting people operationalize ideas directly — what he calls a “superpower” for thinking and creation.

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