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Category: quantum physics

Sean Carroll, CalTech, John’s Hopkins, Santa Fe Institute

One of the great intellectual achievements of the twentieth century was the theory of quantum mechanics, according to which observational results can only be predicted probabilistically rather than with certainty. Yet, after decades in which the theory has been successfully used on an everyday basis, most physicists would agree that we still don’t truly understand what it means. Sean Carroll will discuss the source of this puzzlement, and explain why an increasing number of physicists are led to an apparently astonishing conclusion: that the world we experience is constantly branching into different versions, representing the different possible outcomes of quantum measurements. This could have important consequences for quantum gravity and the emergence of spacetime.

Sean Carroll is a research professor at CalTech, Homewood Professor of Natural Philosophy at John’s Hopkins University, and Fractal Faculty at SFI. His research focuses on fundamental physics and cosmology, quantum gravity and spacetime, philosophy of science, and the evolution of entropy and complexity. He’s authored “Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime;” “The Big Picture;” “The Particle at the End of the Universe;” “From Eternity to Here;” and the textbook “Spacetime and Geometry.”

Scientists just created exotic new forms of matter that shouldn’t exist

A new quantum physics study reveals that simply changing a magnetic field over time can unlock entirely new forms of matter that don’t exist under normal conditions. By carefully “driving” materials with timed magnetic shifts, researchers created exotic quantum states that could be far more stable and resistant to errors—one of the biggest challenges in quantum computing. This breakthrough suggests that the future of quantum technology may depend not just on what materials are made of, but how they’re manipulated in time.

Quantum Error Correction Faces Another Hurdle

Newly identified correlated errors in superconducting qubits could limit the performance of error-correction schemes needed for a practical quantum computer.

Building a working quantum computer is challenging because its basic components, qubits, are highly sensitive to environmental disturbances that compromise computation. Whereas classical bits can only undergo bit-flip errors that change 0 to 1 or vice versa, qubits also suffer from so-called phase errors that degrade the fundamental quantum interference effects essential for quantum computation. Joining several good, but not perfect, physical qubits into a logical qubit makes quantum error correction possible (see Research News: Cracking the Challenge of Quantum Error Correction). But that strategy can fail if too many qubits become faulty at the same time. In one leading hardware platform, superconducting circuits, such correlated qubit errors are typically triggered every few tens of seconds when ionizing radiation from the environment deposits energy into the chip hosting the circuits.

Symmetry says these crystal vibrations can never mix, but an exotic quantum phase rewrites the rules

Symmetry is one of the most fundamental principles in nature. It describes the rules that make an object look unchanged after a rotation, reflection, or other transformations. In materials, symmetry governs how atoms and electrons are arranged, and how they move together. Crucially, symmetry can even prevent certain collective atomic motions (vibrations) from interacting at all: some are simply forbidden to talk to each other. But what if those symmetry restrictions are not as rigid as they seem?

A new study in Nature Physics shows that these constraints can be partially lifted. Researchers at the University of Texas at Austin and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg found that electronic fluctuations can dynamically bridge vibrations that symmetry would normally keep separate. Led by Edoardo Baldini’s group at UT Austin, the study reveals how light, vibrations, and electrons become intertwined in a special type of crystal known as ferroaxial, opening new opportunities for controlling quantum states with light.

The researchers focused on a layered material that at room temperature develops an exotic quantum state. Ions and electrons rearrange together into a static, wave-like pattern known as a charge-density wave (CDW), which manifests as a tiling of star-of-David clusters.

Magnon lifetime extended 100x paves the way for mini quantum computers

Magnons are tiny waves in magnetization that travel through solid magnetic materials, much like the ripples that spread across a pond when a stone is thrown into it. Unlike photons, which travel through empty space or optical fibers, magnons propagate within a magnetic solid. Their wavelengths can be reduced to the nanometer range, meaning that magnonic circuits could, in principle, fit onto a chip no larger than those found in today’s smartphones. Furthermore, as an excitation of a solid, a magnon naturally couples to numerous other fundamental quasi-particles—phonons, photons and others—making it an ideal building block for hybrid quantum systems and quantum metrology.

Until now, there has been one major obstacle: magnons have had a very short lifetime. This lifetime—the period during which they can reliably carry quantum information—was limited to a few hundred nanoseconds at best. Far too short for any practical quantum computation. The team led by Wiener has now achieved a breakthrough: the physicists were able to measure magnon lifetimes of up to 18 microseconds—almost a hundred times longer than any value observed to date.

In this state, magnons are no longer fleeting signals, but become long-lived, reliable carriers of quantum information, comparable to the superconducting qubits used in today’s leading quantum processors. The study has recently been published in the journal Science Advances.

Time-varying magnetic fields can engineer exotic quantum matter

Quantum technology has promising potential to revolutionize how large and complex amounts of information are processed. While already in use primarily in laboratory and research settings globally, quantum technologies are in a transition phase for broader industry applications across many economic sectors.

In researching fundamental aspects of quantum physics, or the behavior of nature at the smallest scales—involving atoms, electrons and photons—a study led by Cal Poly Physics Department Lecturer Ian Powell analyzed how a changing magnetic field can make matter behave in unusual ways.

Powell and student researcher Louis Buchalter, who graduated with a Cal Poly bachelor’s degree in physics in 2025, published the article “Flux-Switching Floquet Engineering” in the journal Physical Review B, highlighting how changing magnetic fields over time can create quantum states that do not exist in any stationary material (remaining in the same state as time elapses).

This New “Sound Laser” Could Measure Gravity With Stunning Precision

A new sound-based laser could measure gravity with unprecedented precision and reshape navigation technology.

Since their introduction in the 1960s, lasers have fueled major advances in science and everyday technology, from supermarket scanners to eye surgery. Traditional lasers operate by controlling photons, which are particles of light. Over the past two decades, researchers have expanded this concept to other particles, including phonons, which represent tiny units of vibration or sound. Learning to control phonons could unlock new capabilities, including access to unusual quantum effects such as entanglement.

Squeezed Phonon Laser Advances Precision.

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