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Category: quantum physics – Page 13

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.

Australian scientists unveil first quantum battery that could one day charge devices in seconds

A new development from Australia’s national science agency is offering a glimpse of a future in which charging your phone, laptop, or even grid-scale storage systems could take a fraction of the time it does now.

Researchers in Australia say they have built the world’s first fully functioning proof-of-concept quantum battery.

Scientists from the CSIRO, the University of Melbourne, and RMIT announced that they had successfully developed and tested a quantum battery prototype, Lab Worldwide reported.

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.

New technique enables LIGO to peer farther into the distant universe

Scientists at the University of California, Riverside, have developed a new way to help gravitational-wave observatories see farther into the universe by solving one of their biggest challenges: tiny heat-induced distortions in the massive mirrors at the heart of the detectors.

The technique, described in a paper published in Classical and Quantum Gravity, uses thermal imaging to reveal microscopic distortions caused by powerful lasers. By measuring those distortions more precisely, observatories such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) could improve their sensitivity and detect weaker, more distant gravitational-wave events.

The goal for the next generation of gravitational-wave detectors is to achieve about 10 times the sensitivity of today’s instruments,” said Jonathan Richardson, an associate professor of physics and astronomy at UC Riverside who led the study. “One of the key obstacles to achieving that is reducing the fundamental quantum-mechanical noise that limits the precision of the measurements.”

From quantum error correction to emergent gravity: Probing holographic universes at QLab

One of the deepest ambitions in modern physics is understanding how the fabric of space and time could emerge from fundamental quantum degrees of freedom to establish a quantum theory of gravity.

In the new paper, “Observation of gravity-like signatures in holographic codes on a quantum computer,” posted to the arXiv preprint server, researchers from the National Quantum Laboratory (QLab@UMD), the Duke Quantum Center, the Virginia Tech Center for Quantum Information Science and Engineering, Caltech’s Institute for Quantum Information and Matter, IonQ and BlueQubit have successfully simulated toy models of quantum gravity according to the AdS/CFT correspondence. The team, led by Crystal Noel and Charles Cao, includes quantum-computation pioneers John Preskill and Christopher Monroe.

Using the IonQ Forte ion-trap quantum computer, the study implements the intriguing HaPPY quantum error-correction code, which forms a bridge between quantum computing and quantum gravity. This code simulates a highly simplified model of a universe with a negative cosmological constant that features a so-called bulk-boundary correspondence, in which the properties of a higher-dimensional gravitational universe (bulk) are completely determined by a lower-dimensional quantum system without gravity living on the boundary. The team successfully demonstrated fundamental entanglement properties of these systems.

Frozen fiber couples light and sound 1,000 times more strongly than standard glass fibers

Researchers have developed a new type of optical fiber by freezing a glass capillary filled with liquid. It guides light and sound waves simultaneously and enables highly efficient coupling between them. The high coupling strength lowers the energy consumption of photonic neuromorphic computing schemes and quantum signal processing applications by several orders of magnitude.

When volcanoes erupt, one can observe streams of liquid lava cool and solidify into rock formations at the bottoms of volcanoes. The same physical process—a liquid changing into a solid phase upon cooling—can be observed when lakes start freezing during cold winters. These phase changes always come with changes in the physical properties of the material, such as the density or refractive index that govern how sound and light move through it.

This fundamental physical process is also used during the melting of glass preforms to loosen their structure while drawing optical fiber. These fibers then guide light through their cores, allowing the transmission of information via light very quickly over long distances, which is why they are widely used for telecommunications applications.

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.”

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