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Category: quantum physics – Page 8

Surgery for quantum bits: Bit-flip errors corrected during superconducting qubit operations

Quantum computers hold great promise for exciting applications in the future, but for now they keep presenting physicists and engineers with a series of challenges and conundrums. One of them relates to decoherence and the errors that result from it: bit flips and phase flips. Such errors mean that the logical unit of a quantum computer, the qubit, can suddenly and unpredictably change its state from “0” to “1,” or that the relative phase of a superposition state can jump from positive to negative.

These errors can be held at bay by building a logical qubit out of many physical qubits and constantly applying error correction protocols. This approach takes care of storing the quantum information relatively safely over time. However, at some point it becomes necessary to exit storage mode and do something useful with the qubit—like applying a quantum gate, which is the building block of quantum algorithms.

The research group led by D-PHYS Professor Andreas Wallraff, in collaboration with the Paul Scherrer Institute (PSI) and the theory team of Professor Markus Müller at RWTH Aachen University and Forschungszentrum Jülich, has now demonstrated a technique that makes it possible to perform a quantum operation between superconducting logical qubits while correcting for potential errors occurring during the operation. The researchers have just published their results in Nature Physics.

VIP-2 experiment narrows the search for exotic physics beyond the Pauli exclusion principle

The Pauli exclusion principle is a cornerstone of the Standard Model of particle physics and is essential for the structure and stability of matter. Now an international collaboration of physicists has carried out one of the most stringent experimental tests to date of this foundational rule of quantum physics and has found no evidence of its violation. Using the VIP-2 experiment, the team has set the strongest limits so far for possible violations involving electrons in atomic systems, significantly constraining a range of speculative theories beyond the Standard Model, including those that suggest electrons have internal structure, and so-called “Quon models.” Their experiment was reported in Scientific Reports in November 2025.

Austrian-Swiss physicist Wolfgang Pauli outlined the exclusion principle in 1925. It states that two identical “fermions” (a class of particles that includes electrons) cannot occupy the same quantum state. It explains why electrons fill atomic shells, why solids have rigidity, and why dense objects such as white dwarf stars do not collapse under gravity.

However, since its inception, physicists have been searching for signs that the Pauli exclusion principle may be violated in extreme conditions. “If the Pauli exclusion principle were violated, even at an extremely small level, the consequences would cascade from atomic physics all the way to astrophysics,” says FQxI member and physicist Catalina Curceanu of the Italian National Institute for Nuclear Physics (INFN), in Frascati, who is the spokesperson of the VIP-2 collaboration.

Tuning topological superconductors into existence by adjusting the ratio of two elements

Today’s most powerful computers hit a wall when tackling certain problems, from designing new drugs to cracking encryption codes. Error-free quantum computers promise to overcome those challenges, but building them requires materials with exotic properties of topological superconductors that are incredibly difficult to produce. Now, researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME) and West Virginia University have found a way to tune these materials into existence by simply tweaking a chemical recipe, resulting in a change in many-electron interactions.

The team adjusted the ratio of two elements— tellurium and selenium —that are grown in ultra-thin films. By doing so, they found they could switch the material between different quantum phases, including a highly desirable state called a topological superconductor.

The findings, published in Nature Communications, reveal that as the ratio of tellurium and selenium changes, so too do the correlations between different electrons in the material—how strongly each electron is influenced by those around it. This can serve as a sensitive control knob for engineering exotic quantum phases.

Glimpsing the quantum vacuum: Particle spin correlations offer insight into how visible matter emerges from ‘nothing’

Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have uncovered experimental evidence that particles of matter emerging from energetic subatomic smashups retain a key feature of virtual particles that exist only fleetingly in the quantum vacuum. The finding offers a new way to explore how the vacuum—once thought of as empty space—provides important ingredients needed to transform virtual “nothingness” into the matter that makes up our world.

The research, just published in Nature, was carried out by the STAR Collaboration at Brookhaven’s Relativistic Heavy Ion Collider (RHIC), a DOE Office of Science user facility for nuclear physics research. The paper presents evidence of a significant correlation in particle spins—a built-in quantum property related to magnetism—among certain pairs of particles emerging from proton-proton collisions at RHIC.

The STAR scientists’ analysis directly links those correlations to the spin alignment of virtual quark-antiquark pairs generated in the quantum vacuum. In essence, the scientists say, RHIC’s collisions give those virtual particles the energetic boost they need to transform into the real particles detected by STAR.

Electron-phonon ‘surfing’ could help stabilize quantum hardware, nanowire tests suggest

That low-frequency fuzz that can bedevil cellphone calls has to do with how electrons move through and interact in materials at the smallest scale. The electronic flicker noise is often caused by interruptions in the flow of electrons by various scattering processes in the metals that conduct them.

The same sort of noise hampers the detecting powers of advanced sensors. It also creates hurdles for the development of quantum computers—devices expected to yield unbreakable cybersecurity, process large-scale calculations and simulate nature in ways that are currently impossible.

A much quieter, brighter future may be on the way for these technologies, thanks to a new study led by UCLA. The research team demonstrated prototype devices that, above a certain voltage, conducted electricity with lower noise than the normal flow of electrons.

Supervised and unsupervised quantum machine learning models for the phase detection of the ANNNI spin model

Based on the paper Quantum phase detection generalization from marginal quantum neural network models, explore the phase diagram of the Axial Next-Nearest-Neighbor Ising (ANNNI) model using both supervised and unsupervised learning methods.

Nothing Is Real: The Simulation Hypothesis

Are we living inside a computer simulation? The evidence is more compelling than you think.

In this deep exploration of the Simulation Hypothesis, we examine the scientific and philosophical arguments that suggest our reality might be code. From Nick Bostrom’s groundbreaking trilemma to quantum mechanics acting like a computer program, from the fine-tuned constants of physics to Elon Musk’s probabilistic arguments—we follow the evidence wherever it leads. Whether we’re simulated or not, the question reveals profound truths about consciousness, reality, and what it means to be human.

CHAPTERS:

0:00 — The Uncomfortable Question.

4:47 — Nick Bostrom’s Trilemma: The Logical Trap.

9:34 — The Ancestor Simulation Scenario.

Continue reading “Nothing Is Real: The Simulation Hypothesis” | >

Realization of two-dimensional discrete time crystals with anisotropic Heisenberg coupling

Experimental realizations of discrete time crystals have mainly involved 1D models with Ising-like couplings. Here, the authors realize a 2D discrete time crystal with anisotropic Heisenberg coupling on a quantum simulator based on superconducting qubits, uncovering a rich phase diagram.

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