Lifeboat Foundation

Implementing a fault-tolerant quantum processor requires coupling qubits to generate entanglement. Superconducting qubits are a promising platform for quantum information processing, but scaling up to a full-scale quantum computer necessitates interconnecting many qubits with low error rates. Traditional methods often limit coupling to nearest neighbors, require large physical footprints, and involve numerous couplers, complicating fabrication.

For instance, coupling 100 qubits pairwise demands a vast number of couplers. Moreover, controlling individual circuit elements and couplers with separate cables for even 1,000 qubits would require an impractically large volume of cables, making it infeasible to fit such a system in a large lab, let alone manage millions of qubits. This highlights the need for more efficient and scalable coupling methods.

A team of theoretical physicists led by Mohd Ansari at FZJ, in collaboration with the experimental team of Britton Plourde at Syracuse University, introduced a novel approach using a multimode coupler that enables tunable coupling strength between any pair of qubits.

Electrons inherently carry both spin and orbital angular momentum (i.e., properties that help to understand the rotating motions and behavior of particles). While some physicists and engineers have been trying to leverage the spin angular momentum of electrons to develop new technologies known as spintronics, these particles’ orbital momentum has so far been rarely considered.

Currently, generating an orbital current (i.e., a flow of orbital angular momentum) remains far more challenging than generating a spin current. Nonetheless, approaches to successfully leverage the orbital angular momentum of electrons could open the possibility for the development of a new class of devices called orbitronics.

Researchers at Keio University and Johannes Gutenberg University report the successful generation of an orbital current from magnetization dynamics, a phenomenon called orbital pumping. Their paper, published in Nature Electronics, outlines a promising approach that could allow engineers to develop new technologies leveraging the orbital angular momentum of electrons.

Charge density waves are quantum phenomena occurring in some materials, which involve a static modulation of conduction electrons and the periodic distortion of the lattice. These waves have been observed in numerous condensed matter materials, including high-temperature superconductors and quantum Hall systems.

While many studies have investigated these states, so far experimental observations of the boundary states that emerge from charge density waves are still scarce. In a recent paper, published in Nature Physics, researchers at Princeton University and other institutes worldwide have visualized the bulk and boundary modes of the charge density wave in the topological material Ta₂Se₈I.

“Our research group focuses on discovering and investigating novel topological properties of quantum matter utilizing various state-of-the-art experimental techniques that probe electronic structure of the materials,” Maksim Litskevich, co-author of the paper, told Phys.org. “In recent years, the physics community has experienced excitement exploring the intriguing and rich properties of Kagome materials, which intricately intertwine geometry, topology, and electronic interactions.”

In a study published in Nature, a research team has, for the first time, observed the antiferromagnetic phase transition within a large-scale quantum simulator of the fermionic Hubbard model (FHM).

This study highlights the advantages of quantum simulation. It marks an important first step towards obtaining the low-temperature phase diagram of the FHM and understanding the role of quantum magnetism in the mechanism of high-temperature superconductivity. The team was led by Prof. Pan Jianwei, Prof. Chen Yuao, and Prof. Yao Xingcan from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences.

Strongly correlated quantum materials such as high-temperature superconductors are of scientific importance and have potential economic benefits. However, the physical mechanisms underlying these materials remain unclear, posing challenges to their large-scale preparation and application.

A team of experimental physicists led by the University of Cologne have shown that it is possible to create superconducting effects in special materials known for their unique edge-only electrical properties. This discovery provides a new way to explore advanced quantum states that could be crucial for developing stable and efficient quantum computers.

Their study, titled “Induced superconducting correlations in a quantum anomalous Hall insulator,” has been published in Nature Physics.

Superconductivity is a phenomenon where electricity flows without resistance in certain materials. The quantum anomalous Hall effect is another phenomenon that also causes zero resistance, but with a twist: It is confined to the edges rather than spreading throughout.

The Brewster reflectionless effect stands out as one of the simplest yet pivotal discoveries in manipulating waves. Initial investigations were limited to isotropic materials, but later, thanks to the advent of metamaterials, the phenomenon was found to expand into anisotropic materials.

An anomalous Brewster effect has recently been demonstrated in metamaterials, thus increasing the number of degrees of freedom. In materials without magnetic responses, the Brewster effect exclusively applies to transverse–magnetic (TM, or p–wave polarization) waves. Building on the equivalence between TM mode and 2D acoustics, the Brewster effect in acoustics with zero reflection has been demonstrated by utilizing acoustic metamaterials.

In their paper published in the journal Science Bulletin, the researchers first demonstrated this universal theory by matching the continuous boundary conditions and analyzing the relationship between the reflection coefficient and various parameters, proposing a precise method to confirm the near-zero reflection condition. Subsequently, they incorporated intrinsic losses into the permittivity tensors, illustrating a novel method to achieve asymmetric vortex transmission.

While taking snapshots with the high-speed electron camera at the Department of Energy’s SLAC National Acceleratory Laboratory, researchers discovered new behavior in an ultrathin material that offers a promising approach to manipulating light that will be useful for devices that detect, control or emit light, collectively known as optoelectronic devices, and investigating how light is polarized within a material. Optoelectronic devices are used in many technologies that touch our daily lives, including light-emitting diodes (LEDs), optical fibers and medical imaging.

As reported in Nano Letters, the team, led by SLAC and Stanford professor Aaron Lindenberg, found that when oriented in a specific direction and subjected to linear terahertz radiation, an ultrathin film of tungsten ditelluride, which has desirable properties for polarizing light used in optical devices, circularly polarizes the incoming light.

Terahertz radiation lies between the microwave and the infrared regions in the electromagnetic spectrum and enables novel ways of both characterizing and controlling the properties of materials. Scientists would like to figure out a way to harness that light for the development of future optoelectronic devices.

Up to 3% of people with diabetes have an allergic reaction to insulin. A team at Forschungszentrum Jülich has now studied a method that could be used to deliver the active substance into the body in a masked form—in the form of tiny nanoparticles.

The insulin is only released in the target organ when the pH value deviates from the slightly alkaline environment in the blood. The molecular transport system could also serve as a platform for releasing other drugs in the body precisely at the target site.

It’s an old dream in pharmacy: To deliver an active ingredient to the exact place in the body where it is most needed—a cancer drug, for example, directly to the tumor tissue. This minimizes its side effects on other organs and ensures that it has its maximum effect at its target.

Using the High-Altitude Water Cherenkov (HAWC) observatory, an international team of astronomers has observed a very-high energy gamma-ray source designated TeV J2032+4130. Results of the observational campaign, presented July 3 on the preprint server arXiv, provide crucial information regarding the nature of this source.

Sources emitting gamma radiation with photon energies between 100 GeV and 100 TeV are called very-high energy (VHE) gamma-ray sources, while those with photon energies above 0.1 PeV are known as ultra-high energy (UHE) gamma-ray sources. The nature of these sources is still not well understood; therefore, astronomers are constantly searching for new objects of this type to characterize them, which could shed more light on their properties in general.

TeV J2032+4130 was identified in 2005 by the High Energy Gamma Ray Astronomy (HEGRA) experiment as the first VHE gamma-ray source in the TeV range with no lower-energy counterpart. Previous observations of TeV J2032+4130 have revealed that it consists of two sources, namely HAWC J2030+409 and HAWC J2031+415, which is coincident with a pulsar wind nebula (PWN).