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Category: quantum physics

Probability theorem gets quantum makeover after 250 years

How likely you think something is to happen depends on what you already believe about the circumstances. That is the simple concept behind Bayes’ rule, an approach to calculating probabilities, first proposed in 1763. Now, an international team of researchers has shown how Bayes’ rule operates in the quantum world.

“I would say it is a breakthrough in ,” said Professor Valerio Scarani, Deputy Director and Principal Investigator at the Center for Quantum Technologies, and member of the team. His co-authors on the work published on 28 August 2025 in Physical Review Letters are Assistant Professor Ge Bai at the Hong Kong University of Science and Technology in China, and Professor Francesco Buscemi at Nagoya University in Japan.

“Bayes’ rule has been helping us make smarter guesses for 250 years. Now we have taught it some quantum tricks,” said Prof Buscemi.

“Heavy” Electrons Hold the Key to a New Type of Quantum Computer

Discovery of Planckian time limit offers new opportunities for quantum technologies. A collaborative team of researchers in Japan has identified “heavy fermions”—electrons with greatly increased effective mass—that display quantum entanglement controlled by Planckian time, the fundamental unit of

Quantum internet is possible using standard Internet protocol — University engineers send quantum signals over fiber lines without losing entanglement

Engineers at the University of Pennsylvania have successfully sent quantum signals over a standard internet connection with fiber-optic cables in the real world. The researchers have published their work in Science, taking the quantum internet from theory to reality by using existing internet systems.

Quantum signals are famously weak, unable to be measured without losing their quantum entanglement and becoming unreadable with too much noise. But engineers have managed to send the signals over the same busy internet infrastructure that standard IP signals occupy.

A blueprint for error-corrected fermionic quantum processors

An international research team led by Robert Ott and Hannes Pichler has developed a novel architecture for quantum processors that is specifically designed for simulating fermions—particles such as electrons. The method can be implemented using technologies already available today.

Two new methods push graphene’s electronic quality beyond traditional semiconductors

Graphene, a single sheet of carbon atoms arranged in a honeycomb lattice, is known for its exceptional strength, flexibility and conductivity. However, despite holding the world record for room-temperature electron mobility, graphene’s performance at cryogenic temperatures has remained below that of the best gallium arsenide (GaAs)-based semiconductor systems, which have benefited from many decades of refinement.

One key obstacle is electronic disorder. In practical devices, is highly sensitive to stray electric fields from charged defects in surrounding materials. These imperfections create spatial fluctuations in , known as electron-hole puddles, that scatter electrons and limit mobility. This disorder has prevented graphene from realizing its full potential as an ultra-clean electronic system.

Now, in two parallel studies, researchers from the National University of Singapore (NUS) and The University of Manchester (UK) report distinct strategies that finally push graphene past this long-standing benchmark. The results set new records for electron mobility, matching and in some cases surpassing GaAs in both transport and quantum mobility, and enabling the observation of quantum effects in unprecedented conditions.

Engineers send quantum signals with standard Internet Protocol

In a first-of-its-kind experiment, engineers at the University of Pennsylvania brought quantum networking out of the lab and onto commercial fiber-optic cables using the same Internet Protocol (IP) that powers today’s web.

Reported in Science, the work shows that fragile quantum signals can run on the same infrastructure that carries everyday online traffic. The team tested their approach on Verizon’s campus fiber-optic network.

The Penn team’s tiny “Q-chip” coordinates quantum and classical data and, crucially, speaks the same language as the modern web. That approach could pave the way for a future “quantum internet,” which scientists believe may one day be as transformative as the dawn of the online era.

A low-cost protocol enables preparation of magic states and fault-tolerant universal quantum computation

Quantum computers, systems that perform computations leveraging quantum mechanical effects, could outperform classical computers in some optimization and information processing tasks. As these systems are highly influenced by noise, however, they need to integrate strategies that will minimize the errors they produce.

One proposed solution for enabling fault-tolerant quantum computing across a wide range of operations is known as state . This approach consists of preparing special quantum states (i.e., magic states) that can then be used to perform a universal set of operations. This allows the construction of a universal quantum computer—a device that can reliably perform all operations necessary for implementing any quantum algorithm.

Yet while magic state distillation techniques can achieve good results, they typically consume large numbers of error-protected qubits and need to perform many rounds of error correction. This has so far limited their potential for real-world applications.

How an in-between quantum state could boost future technologies

Kai Sun of the University of Michigan is a humble physics professor with ambitious goals. “I’m mainly a paper-and-pencil type of theorist, doing analytical calculations mostly,” Sun said. “My interests are pretty broad, but basically searching for new fundamental principles and new phenomena, especially new phenomena and new physics previously believed to be impossible.”

How a superfluid simultaneously becomes a solid

In everyday life, all matter exists as either a gas, liquid, or solid. In quantum mechanics, however, it is possible for two distinct states to exist simultaneously. An ultracold quantum system, for instance, can exhibit the properties of both a fluid and a solid at the same time.

The Synthetic Quantum Systems research group at Heidelberg University has now demonstrated this phenomenon using a new experimental approach, by feeding a small amount of energy into a superfluid. They showed that, in a driven quantum system of this kind, propagate at two different speeds, which points toward coexisting liquid and solid states, a hallmark of supersolidity. The work is published in the journal Nature Physics.

This surprising and seemingly contradictory behavior of two states of matter existing at the same time does not occur at room temperature. But at ultralow temperatures, takes over, and matter can exhibit fundamentally different properties. When atoms are cooled to such low temperatures, their wave-like nature is dominant. If brought close enough together, many particles merge into one large wave, known as a Bose-Einstein condensate. This state is a superfluid, a fluid that flows without friction.

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