Lifeboat Foundation

Quantum walks are a powerful theoretical model using quantum effects such as superposition, interference and entanglement to achieve computing power beyond classical methods.

A research team at the National Innovation Institute of Defense Technology from the Academy of Military Sciences (China) recently published a review article that thoroughly summarizes the theories and characteristics, physical implementations, applications and challenges of quantum walks and quantum walk computing. The review was published Nov. 13 in Intelligent Computing in an article titled “Quantum Walk Computing: Theory, Implementation, and Application.”

As quantum mechanical equivalents of classical random walks, quantum walks use quantum phenomena to design advanced algorithms for applications such as database search, network analysis and navigation, and quantum simulations. Different types of quantum walks include discrete-time quantum walks, continuous-time quantum walks, discontinuous quantum walks, and nonunitary quantum walks. Each model presents unique features and computational advantages.

A method for imaging spin waves in magnetic materials uses flash-like intensity variations in a laser beam to capture the wave motion at specific moments in time.

The magnetic moments, or spins, in certain materials can twirl in a coordinated wave pattern that might one day be used to transmit information in so-called spintronic devices. Researchers have developed a new way to image these spin waves using an infrared laser that essentially flashes on and off at a frequency that matches that of the spin waves [1]. Unlike other spin-wave probes, this strobe method can directly capture phase information that is relevant to certain applications, such as hybrid devices that combine spin waves with other types of waves.

A spin wave can be triggered in a magnetic material when some perturbation causes a spin to oscillate, which can then generate a wave of oscillations that ripple through neighboring spins. Spin waves have several properties that make them good candidates for information carriers. For one, they have relatively small wavelengths—a few hundred nanometers at a frequency of 1 GHz, whereas a 1-GHz photon has a wavelength of about 30 cm. This compactness could conceivably allow researchers to build spintronic components, such as waveguides and logic gates, at the nanoscale. Another advantage of these waves is that the spins remain in place, and only their orientation changes. So the heat losses that affect the moving charges in traditional electronics don’t exist.

The search for superconductivity in hydrogen-rich compounds known as hydrides has been an emotional rollercoaster ride for the scientific community. Excitement mounted a few years ago, as hydride experiments had physicists imagining that a Holy Grail, room-temperature superconductivity, might be within reach. But the field was shocked in 2023 by allegations of malpractice and fraud. Now a group of physicists—leading superconductivity experts who aren’t involved in hydride research—has offered an independent assessment of the available body of work on these materials [1]. They conclude that there is overwhelming evidence for superconductivity in hydrides.

“The more I read the foundational literature, and the more I learned about the way that results were being repeated, the more it became clear to me that hydride superconductivity is completely genuine,” says Andrew Mackenzie of the Max Planck Institute for Chemical Physics of Solids in Germany and the University of St Andrews in the UK.

Mackenzie was one of the initiators of the group’s work. “At conferences last spring, guys my age were having lots of young people coming up to ask: What’s going on in hydrides?” he says. After a communal discussion at a superconductivity meeting in Berlin in August, he and other researchers thought that something needed to be done to address young researchers’ concerns. They organized a group that would review available data with the goal of delivering an objective evaluation of hydride superconductivity claims, says Jörg Schmalian of the Karlsruhe Institute of Technology in Germany, who is one of the article’s cosigners.

In 2011 physicists made a surprising observation: A cuprate material exposed to intense pulses of light appeared to superconduct fleetingly at a temperature above its critical temperature. Could this be a clue to finding higher-temperature superconductors? The answer remains unclear. “There are still continuing debates about whether the light-induced state is really superconducting,” says Morihiko Nishida from the University of Tokyo. Now he and his colleagues have provided new hints concerning the nature of the light-induced state and its connection to electronic wave patterns called charge-density waves (CDWs) [1].

The researchers studied two cuprates, called LNSCO and LSCO, that both contain the element lanthanum. These materials superconduct at temperatures below 10 K, but at slightly higher temperatures, they transition to one of several low-conductivity states in which a wave pattern is imprinted onto the electron distribution. Previous work by this group suggested that these CDWs play a role in light-induced superconductivity [2], but it was unclear whether the wavelength—short or long—of the CDWs had any effect.

In their new experiments, Nishida and colleagues fired near-infrared pulses at their cuprate samples and recorded the electron response with a terahertz probe beam. In the CDW region of parameter space, they observed a light-induced conducting state whose frequency matched that of a superconducting resonance effect. The implication that the light-induced state is superconducting needs to be confirmed with other experiments, but the team’s work has revealed that both short-and long-wavelength CDWs play a role. The results have a bearing on models that suggest that the pairing of electrons—a key feature of superconductivity—occurs in CDW states at temperatures above the normal onset of superconductivity (see Synopsis: Picking out Waves in a Material’s Charge Distribution).

UC Santa Barbara researchers developed a compact, low-cost laser that matches the performance of lab-scale systems. Using rubidium atoms and advanced chip integration, it enables applications like quantum computing, timekeeping, and environmental sensing, including satellite-based gravitational mapping.

For experiments requiring ultra-precise atomic measurements and control—such as two-photon atomic clocks, cold-atom interferometer sensors, and quantum gates—lasers are indispensable. The key to their effectiveness lies in their spectral purity, meaning they emit light at a single color or frequency. Today, achieving the ultra-low-noise, stable light necessary for these applications relies on bulky and expensive tabletop laser systems designed to generate and manage photons within a narrow spectral range.

But what if these atomic applications could break free from the confines of labs and benchtops? This is the vision driving research in UC Santa Barbara engineering professor Daniel Blumenthal’s lab, where his team is working to replicate the performance of these high-precision lasers in lightweight, handheld devices.

Astronomers have discovered a massive dormant black hole from the early universe, just 800 million years after the Big Bang, using the James Webb Space Telescope.

This black hole, with a mass 400 million times that of our Sun, challenges existing models of black hole growth due to its size and low accretion rate.

Unprecedented black hole size and behavior.

A new model reveals how molecular interactions drive order in active systems.

Scientists from the Department of Living Matter Physics at the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) have found that non-reciprocal interactions can enhance order in active systems. Using a newly developed model, they demonstrated how the degree of non-reciprocity influences the formation of patterns, providing deeper insight into the organization of complex, dynamic systems.

Living matter exhibits unique characteristics not found in simpler physical systems. One striking example is the uneven interaction between different types of particles. For instance, one molecule may be attracted to another, while the second is repelled — similar to how a predator pursues its prey, which instinctively tries to escape. This phenomenon, known as non-reciprocal interaction, can produce complex, large-scale patterns, as has been shown previously. These patterns often resemble essential structures found in living systems, such as the organization within a cell.

Scientists have found evidence of a strange state of matter called a quantum spin liquid in a material known as pyrochlore cerium stannate.

In this mysterious state, magnetic particles don’t settle into a fixed pattern but stay in constant motion, even at extremely low temperatures. Researchers used advanced tools like neutron scattering and theoretical models to detect unusual magnetic behavior that behaves like waves of light. This breakthrough could lead to new discoveries in physics and future technologies like quantum computing.

Quantum Spin Liquids

Scientists used AI to estimate the brain age of 739 healthy seniors and found that lifestyle and health conditions impact brain aging.

Researchers at Karolinska Institutet have used an AI tool to estimate the biological age of brains from MRI scans of 70-year-olds. Their analysis revealed that factors harmful to vascular health, such as inflammation and high blood sugar levels, are linked to older-looking brains, while a healthy lifestyle was associated with younger-looking brains. These findings were published today (December 20) in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

Leveraging AI to determine brain age.