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Category: quantum physics

Quantum randomness helps neural network recognize troublesome handwritten digits

Quantum computing and AI are among the most rapidly developing modern technologies. AI, in the form of machine learning, has been deployed for decades to recommend movies and TV shows and make it easier to search for images. Over the past several years, large language models have permeated even more facets of daily life, from writing emails to producing images, videos and songs in response to requests expressed in a few written lines.

Quantum computers, on the other hand, have remained almost exclusively in labs at universities and a handful of companies. Nevertheless, many researchers and engineers developing them are already looking for the earliest applications and predict a bright future in which quantum computers excel at certain tasks, like drug development and enabling new cryptographic techniques.

Despite machine learning and quantum computing both being heralded as revolutionary technologies, neither is a magic solution to every problem. They are each the products of a long line of research advances and are both still under active study.

Scientists have found a new way molecules can cooperate at room temperature

What if glowing molecules could synchronize, much like fireflies flashing in unison? Researchers have discovered that molecules confined within tiny gold nanostructures can behave collectively, coordinating their interactions even under conditions where this was previously thought impossible. The finding challenges long standing assumptions about how optical coherence forms and opens new possibilities for highly sensitive sensors, molecular photonics, and future quantum technologies capable of operating at room temperature.

Optical coherence describes a state in which light—or the molecules producing it—behaves in a highly coordinated way. It is the principle behind technologies such as lasers, advanced imaging systems and quantum communication. Traditionally, scientists believed this kind of coordinated behavior required specially designed optical cavities that trap light for relatively long periods.

Cesium atoms and quantum dots generate indistinguishable photons for modular quantum networks

Large-scale quantum communication networks require both reliable quantum memories and coherent single-photon sources that can exchange quantum information efficiently. A coherent source of single photons with narrow linewidth, high brightness, spectral uniformity and compatibility with quantum memories is necessary. While a variety of single-photon sources, such as quantum dots (QDs) and atoms in warm vapor cells, have been developed in recent years, each has inherent limitations, making a scalable and functional quantum network challenging to achieve.

Hybrid quantum architectures that combine different quantum light sources can address these challenges. For example, QDs, which suffer from spectral randomness and are not well suited for photon storage, can be paired with atomic systems that provide reliable frequency standards and quantum memories. In such architectures, QDs can serve as bright, high-rate photon sources, while atomic systems handle photon storage and synchronization.

However, a key challenge in realizing such hybrid quantum architectures is interfacing different quantum light sources. Single photons emitted from different sources exhibit distinct spatial and temporal properties, necessitating modifications and synchronization that introduce losses and increase resource needs.

Physicists create Bose–Einstein condensate from ultracold polar molecules

Bose–Einstein condensates are states of matter that form when particles called bosons are cooled to temperatures that are only a fraction of a degree above absolute zero (i.e., 0 Kelvin [-460°F]). In these states, particles occupy the same quantum state and exhibit interesting collective behaviors, essentially behaving as if they were a single “super-particle.”

So far, physicists have primarily created Bose–Einstein condensates using atoms. The first realization of these states with molecules was just over two decades ago, in 2003.

Producing Bose–Einstein condensates with ultracold polar molecules, cooled molecules in which positive and negative charges are separate, has proved particularly challenging. This is partly due to chemical reactions that can cause a loss of these molecules while they are being cooled.

Light’s hidden properties save quantum information from the chaos of bad weather

For years, researchers have tried to harness the “twist” of light to transmit data. This property describes how light spirals as it travels forward, and because it can be molded into a virtually infinite number of different twists, it provides a massive, promising alphabet for high-capacity communication.

This twisted light has proven notoriously fragile in real-world environments such as bad weather, atmospheric turbulence and water. Once it passes through these chaotic media, the twisted pattern becomes completely unrecognizable, a major historical barrier that has stalled the use of this large alphabet for global communications.

By sending quantum information through a storm, researchers at The University of the Witwatersrand in Johannesburg, South Africa, have shown that the information in light can be kept completely intact, even though the light itself was completely warped beyond recognition.

Quantum in the palm of your hand: The evolution of superconducting qubits

Electrons zipping through transistors, powering the screens on our smartphones. Light zooming from distant stars to Earth, moving faster than anything else in the universe. Protons enabling MRI machines to analyze people’s injuries.

Quantum mechanics explains the behavior of subatomic particles like electrons, photons and protons. In contrast to classical physics that we can observe with our senses, particles in the quantum realm have unusual behaviors. Even though quantum particles make common technologies possible, we don’t experience these behaviors in our everyday world.

That’s why a discovery in 1985 was such a big deal. In a laboratory at the University of California, Berkeley, a team of three scientists showed that a system you could see could demonstrate quantum behavior. Or as they said in one of the journal articles covering the experiments, the system was “big enough to get one’s grubby fingers on.”

Physicists link the Riemann Hypothesis to phase transitions in quantum systems

A new study in Nature Communications has established a link between the Riemann Hypothesis and dynamical phase transitions in engineered quantum systems, demonstrating the effect on a quantum processor.

First posed in 1859, the Riemann Hypothesis is one of the longest-standing unsolved problems in mathematics. It underpins parts of cryptography, as well as more than a thousand theorems proved on the assumption that it is true.

Physicists have previously proposed physical counterparts to this mathematical statement. The aim was to map the Riemann Hypothesis to something concrete, such as the energy levels of a quantum system. The new study ties the hypothesis to how a quantum system evolves over time.

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