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Category: particle physics – Page 4

Detecting the body’s magnetic fields with a low-power Ramsey-based magnetometer

Our bodies generate extremely weak magnetic fields as electric currents flow through the heart, brain and other tissues. These signals are used in magnetocardiography and magnetoencephalography to assess heart function and brain activity, respectively. These fields can be detected at room temperature using diamond sensors containing nitrogen-vacancy (NV) centers, in which a carbon atom is replaced by a nitrogen atom adjacent to an empty lattice site.

However, conventional NV-center sensors typically require watt-level lasers to detect the extremely weak biomagnetic fields, which are usually below the picotesla level. These high-power lasers generate significant heat, limiting how close the sensor can be placed to biological tissue. Since biomagnetic fields rapidly weaken with distance, overcoming thermal and close-proximity challenges is essential for practical biomagnetic sensing.

A research team led by Professor Takayuki Iwasaki from the Department of Electrical and Electronic Engineering, School of Engineering, Institute of Science Tokyo, Japan, has developed a diamond quantum magnetometer using a low-power laser of just 210 mW, a light-trapping diamond waveguide and a compact microwave antenna. The new sensor limits its temperature rise to only 13 K while allowing it to be placed just 2 mm (0.08 inches) from the sample, enabling close-proximity biomagnetic measurements without compromising thermal safety.

The First Room-Temperature Quantum Material of Its Kind Is Spun From Atoms of Gold

Materials in a quantum state come with exotic properties that bend the laws of physics and offer huge potential to scientists – but they’re usually also incredibly delicate, and require ultra-low temperatures to exist and function.

That presents a problem when it comes to making the most of these materials and their characteristics: they need to move out of large lab refrigerators.

We’re now another step towards that being possible.

A Map to a Long-Sought Quantum Simulator

The Sachdev-Ye-Kitaev (SYK) model describes information scrambling in black holes and an unusual metallic phase in high-temperature superconductors. Despite those and other far-reaching applications, realizing the model in the lab has been extremely challenging because the particle interactions required are intricate and long-ranged. Now Charles Creffield at the Complutense University of Madrid and his colleagues have detailed how this model could be simulated in existing cold-atom setups [1]. Their strategy provides a practical path to exploring quantum phenomena that are currently confined to theory.

Rather than engineer the requisite particle interactions from the outset, the team started with a much simpler setup emulating the Hubbard model, which is used to understand how electrons moving in a lattice give rise to superconductivity and other phenomena. Ultracold atoms are placed in a one-dimensional optical lattice, where they hop between lattice sites and mutually repel each other when occupying the same site. The lattice is then periodically shaken to make the rate of hopping oscillate in time. This modulation suppresses the atoms’ ordinary motion and generates effective interactions between all the atoms at once, closely resembling the particle behavior of the SYK model.

Using detailed numerical simulations, the researchers went on to show that their Hubbard-based system reproduces several key features of the SYK model, including its characteristic chaotic dynamics and fast spreading of quantum information. The team emphasizes that its approach could be enacted straightforwardly using currently available cold-atom technologies. Such an implementation would offer a controlled, versatile platform for simulating the SYK model and possibly for probing the uncertain physics of quantum chaos and quantum gravity.

Aligned graphite particles unlock stable levitation above magnets, study finds

A diamagnetic substance is slightly repelled by magnetic fields. With a strong enough magnet, the diamagnetic force can override gravity, and the substance will float in the air. Graphite, the main component of pencil lead, is considered one of the best substances for such real-world levitation, and its potential application in sensing weak external perturbations is drawing growing interest.

Until recently, graphite’s electrical conductivity posed an obstacle because electric currents suppress this levitation. Previous research found that a glass coating efficiently blocks the current but also causes the particles to point in all directions, weakening the lifting force.

A team of researchers at Kyoto University happened to be developing a possible solution: making single-crystal equivalents of various substances from fine powders by aligning microcrystals in a uniform direction. Though the scientists specialize in nuclear magnetic resonance spectroscopy, once they came across the graphite levitation issue, they realized they could make a substantial contribution to solving this conundrum.

Quantum sensing microscope illuminates transistor design

Artificial intelligence faces an energy crisis stemming from a physical traffic jam inside modern computer chips. Processors must continually shuffle data, such as the billions of parameters in complex models, between separate computing and memory nodes. This traffic jam, known as the “von Neumann bottleneck,” hinders the speed and energy efficiency of advanced processors.

To tackle this problem, scientists are developing spintronics, which leverages the electron’s “spin,” or intrinsic magnetic orientation, for more efficient devices. A long-sought milestone in this field is a single device, known as a “spin transistor,” that combines a magnetic bit with a semiconducting switch, allowing it to compute and store data simultaneously.

“The major challenge is understanding how magnetism and electrical current interact in nanoscale devices,” said Boston College physics professor Brian Zhou, whose group led the study. “We developed a single-spin quantum microscope to observe magnetic states inside atomically thin devices as they actively process electrical information.”

A New Compact Instrument Enables High-Fidelity Measurements of Energetic Particles on CubeSats

Successfully launched on July 23, 2025, the REAL instrument can distinguish between these potential modes, making it possible to investigate their relative importance and determine which, if any, waves are responsible for electron fallout. Leveraging recent advancements in sensor miniaturization, the instrument includes three sensor heads — a low-, medium-, and high-energy head with two, five, and four simultaneous look directions, respectively — integrated with four electronic boards. Together, they occupy only about half of the REAL CubeSat and use a time resolution sufficient to resolve microbursts of electrons with energies ranging from 40 keV up to 2 MeV. As its parent 3U CubeSat flies in LEO, REAL points along Earth’s magnetic field and can simultaneously measure the quantity, energy, and angle of the particles as they fall into the atmosphere — a first-of-its-kind capability.

“Most CubeSats can observe particles from only a single direction, so they have to spin in order to build up a full picture — and that takes a few seconds, too slow to capture microbursts,” said space physicist Robyn Millan of Dartmouth College, who serves as the REAL mission principal investigator. “With REAL, we’ve managed to squeeze three sensors, each with multiple look directions, into the top of this 100-by-100-millimeter head, allowing us to capture those measurements all at once. We’re really proud of that.”

The high-energy head consists of a 30-millimeter-thick aluminum collimator with four apertures, each spanning 20 degrees of pitch angle. Each aperture connects to an active area on a solid-state detector (SSD) at the base. The medium-energy head similarly uses an SSD base but instead employs five active areas that connect to a 22-millimeter-thick aluminum collimator with five apertures, each spanning 20 degrees of pitch angle. The low-energy head, on the other hand, is a miniature electrostatic analyzer (ESA) consisting of titanium electrodes sandwiched between etched silicon selector slits. These lie on top of a microchannel plate (MCP). The low-energy head uses 36 apertures, two look directions (±40 degrees), and 15 channels to measure electrons with lower energies, from 1 keV to 40 keV.

Everything from cells to stars to particles exists on the edge of chaos

Complex systems, be they living beings or fundamental particles, need to have enough structure to hang together along with unpredictability that can allow for change. Columnist Thomas Lewton explores whether this idea is simply a pattern seen across the cosmos or could be a “theory of everything”

Noise Proofing Molecules for New-Physics Searches

Certain molecules can be placed into states that are less sensitive to external noise, offering researchers a quiet system for probing fundamental physics.

Molecules are like tiny sandboxes for exploring fundamental physics. Within the molecular environment, bound electrons and nucleons can be exposed to exceptionally strong fields, inducing effects that can’t easily be observed elsewhere. By measuring transitions within these molecules, researchers can look for small deviations from theory, which could be signs of new physics beyond the standard model of particle physics. However, molecules are very sensitive to external fields, causing “noise” that can hide the small internally induced deviations. Yuiki Takahashi and colleagues at Caltech have come up with a potential solution, which counterintuitively uses external fields to make molecules immune to external fields [1]. By exposing small triatomic molecules to carefully tuned electromagnetic fields, the researchers have placed the molecules into special states where their sensitivity to noise is reduced by a factor of several hundred.

The Large Hadron Collider is being upgraded so that it can unlock the secrets of the Higgs boson

Deep beneath the French-Swiss border, the world’s largest scientific instrument has fallen silent. After years of smashing protons together at nearly the speed of light, CERN’s Large Hadron Collider (LHC) has stopped operations and entered a long shutdown.

While no particle collisions are taking place at the LHC, thousands of scientists, engineers and technicians are dismantling parts of the machine, installing new technologies and preparing one of the most ambitious upgrades ever attempted in experimental physics.

When it switches on again, around 2030, it will become the High-Luminosity Large Hadron Collider (HL-LHC), capable of delivering roughly seven times more data than the collider that discovered the Higgs boson.

How quantum circuits based on neutral atoms could find and fix errors

Quantum computers, devices that process information by leveraging the laws of quantum mechanics, have been found to outperform classical computers in some advanced tasks. Instead of storing information in the form of classical binary bits (i.e., 0 or 1), quantum computers rely on quantum bits (i.e., qubits), which can also exist in combinations of 0 and 1 states.

Despite their potential, quantum computers are known to be highly prone to errors. This is because qubits are very sensitive to heat, magnetic fields and other changes in their surroundings, which can disrupt the delicate quantum states they rely on to store and process data.

Researchers at Princeton University recently introduced a new approach for developing quantum computers that make fewer errors and whose errors are easier to detect and correct.

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