A new method reveals hidden order in quantum systems, potentially transforming how they are measured and used.
Category: computing – Page 27
Quantum Simulations Now Model Energy Loss With Greater Accuracy
A new computational technique accurately models decoherence’s impact on light–matter interactions within waveguide quantum electrodynamics. Matias Bundgaard-Nielsen and colleagues at the Technical University of Denmark present a matrix product state (MPS) method capable of modelling decoherence processes via density matrices, representing a key advancement over previous approaches. The method utilises collision quantum optics and efficiently incorporates various loss mechanisms, including emitter pure dephasing and off-chip radiative decay, to simulate complex waveguide QED systems such as two-level systems and multi-emitter setups. By modelling these realistic dissipation dynamics, the research offers vital insights into the behaviour of quantum systems and enables improved designs for quantum technologies.
A six-fold increase in simulated timescales for waveguide quantum electrodynamics has been achieved, surpassing limitations that previously restricted simulations to Markovian dynamics. This advancement results from employing a density matrix-based matrix product state (MPS) method, enabling accurate modelling of non-Markovian effects arising from time delays and memory effects within the system.
Traditionally, waveguide QED simulations have relied on the Markov approximation, which assumes that the system’s memory of past events is negligible. However, in many realistic scenarios—particularly those involving long propagation delays within the waveguide or slow emitter dynamics—this approximation breaks down. The method explicitly accounts for the system’s history, allowing the simulation of phenomena that depend on non-Markovian effects. In particular, it incorporates realistic decoherence mechanisms such as pure dephasing, which perturbs the phase coherence of quantum states, and off-chip radiative decay, where excitation energy is lost to the environment outside the waveguide.
Ion Clock Experiments Reveal Time Can Go Quantum
PRESS RELEASE — Few concepts in physics are as familiar, yet as enigmatic, as time. In Einstein’s theory of relativity, time is not absolute: its passage depends on motion and gravity. But when combined with quantum physics, this relativistic form of time becomes even more counterintuitive. According to quantum theory, the flow of time itself may exist in a genuine quantum superposition, ticking faster and slower at the same time. Now, a new paper titled Quantum signatures of proper time in optical ion clocks, published on April 20, 2026 in Physical Review Letters, the premier physics research journal, shows that this striking possibility may soon be tested in the laboratory.
In this work, a team led by Assistant Professor of theoretical physics Igor Pikovski at Stevens Institute of Technology, in collaboration with experimental groups of Christian Sanner at Colorado State University and Dietrich Leibfried at the National Institute of Standards and Technology (NIST), explores quantum aspects of the flow of time and how they can be accessed with atomic clocks. Their results suggest that the same quantum technologies being developed for next-generation clocks and quantum computers may soon probe something far more fundamental: When a clock’s motion obeys quantum mechanics, its movement can exist in superposition, and with it the recorded passage of time itself. This is analogous to Schrödinger’s famous thought experiment, where the counterintuitive nature of quantum superposition is illustrated by a cat being both alive and dead; here it is the passage of time itself that is in superposition, like a cat that is both young and old at once.
“Time plays very different roles in quantum theory and in relativity,” says Pikovski. “What we show is that bringing these two concepts together can reveal hidden quantum signatures of time-flow that can no longer be described by classical physics.”
First direct nanomagnet measurement finds switching attempts far slower than long-assumed
A compass always points north—or does it? Magnets normally maintain a stable direction of magnetization, pointing from south to north (S→N). However, this direction can change under strong magnetic fields or heat. For example, a compass placed near a strong magnet may no longer point in the right direction.
Magnets can also lose their magnetism when exposed to high levels of heat. This isn’t just relevant to wayfinding during your camping trips—if the magnets in hard drives and memory storage devices are affected, it could mean losing all of your precious data.
Researchers at Tohoku University sought to better understand the intricate ways in which this thermally-activated switching occurs in nanomagnets, and successfully measured it experimentally for the very first time. The results are published in Communications Materials.
Gene-screen strategy separates Parkinson’s promoters from protectors, revealing new drug targets
A novel strategy that combines computational and experimental approaches has allowed researchers at Baylor College of Medicine and the Duncan Neurological Research Institute (Duncan NRI) at Texas Children’s Hospital to distinguish alterations in gene function that contribute to Parkinson’s disease from those that protect from the condition. The study, published in Neurobiology of Disease, revealed novel risk factors and previously unrecognized therapeutic targets, offering hope for a future in which effective therapies will be available to prevent, slow down or stop this devastating disease.
“Parkinson’s disease is the most common neurodegenerative movement disorder—it affects more than 10 million people worldwide,” said corresponding author Dr. Juan Botas, professor of molecular and human genetics and molecular and cellular biology at Baylor. Botas also is a member of the Duncan NRI and director of the High Throughput Behavioral Screening Core at Texas Children’s.
“People with the condition have tremors, muscle stiffness and balance problems. They move slowly with a shuffling gait; their symptoms often start gradually and worsen over the years. Current therapies only relieve symptoms but do not prevent the gradual loss of brain cells called neurons that cause the disease,” said Dr. Botas.
Scientists invent artificial neurons that ‘talk’ to real brain cells, paving way to better brain implants
Engineers have printed tiny, artificial neurons that can “talk” to mouse brain cells, and the development could pave the way to innovations in computing and medicine.
The work, published April 15 in the journal Nature Nanotechnology, adds to a growing field that aims to build computers that mimic the inner workings of the brain.
On computing quantum waves exactly from classical action
The fundamental quantum postulates on the existence of a wave function, its propagation with the Schrödinger equation in theorem 3.2 and the wave collapse at a measurement in lemma 3.3 are derived from the classical theorem 2.4. Furthermore, analytic computations of the classical action are simpler than solving the Feynman path integral and potentially easier than solving the Schrödinger equation directly. In addition, theorem 3.2 is a multi-particle result.
The J classical multipaths in theorem 3.2 and lemma 3.3 are strictly determined by the initial and final conditions. In the double slit experiment, the probabilistic quantum observation results from the non-Lipschitz constraint force in the slit. For the harmonic oscillator, the Coulomb wave, the particle in the box, or the spinning particle, the initial probabilistic density distribution is classically propagated forward in time. In the EPR experiment [64,65], theorem 2.4 determines a constant angular momentum χo↑,χo↓ over time, and lemma 3.3 in turn allows a classical interpretation that the decision which spin correlation is sensed behind the filters is already taken when the particles separate.
Quantum chips could scale faster with new spin-qubit readout that reduces sensors and wiring
Quantum computers, devices that process information leveraging quantum mechanical effects, could tackle some tasks that are difficult or impossible to solve using classical computers. These systems represent data as qubits, units of information that can exist in multiple states at once, unlike the bits used by classical computers that represent data using binary values (“0” or “1”).
Some of the quantum computers developed in recent years store quantum information in the spin (i.e., intrinsic angular momentum) of electrons or nuclei that are trapped in small semiconductor-based structures, known as quantum dots. For these devices to operate reliably, however, engineers need to be able to precisely measure the quantum states of the spin qubits they rely on, a process that is known as qubit readout. It would also be advantageous for these states to be precisely measured in a way that is architecturally compact, or in other words, using space-efficient hardware as opposed to numerous bulkier components.
Researchers at Quantum Motion and University College London (UCL) recently introduced a new approach to clearly read out the states of spin qubits leveraging high-frequency electrical signals. This method, introduced in a paper published in Nature Electronics, was developed by Jacob F. Chittock-Wood and his colleagues while he was completing his Ph.D. at UCL.