Letters

Unconventional superconductivity is often associated with the presence of other kinds of electronic order. Observations of charge order in infinite-layer nickelate superconductors show that they fit this pattern.

Qudits are generalizations of qubits that have more than two states, which gives them a performance advantage in some quantum algorithms. The operations needed for a universal qudit processor have now been demonstrated using trapped ions.

Both inter- and intraband transitions contribute to high-harmonic generation in solids, but their exact roles are not fully understood. Experiments with quantum dots show that enhanced intraband transitions lead to increased carrier injection and thus enhanced harmonic generation.

A method to engineer higher-order interactions between photons provides a route to create non-classical and entangled states across multiple modes.

Magnetic skyrmions—a type of localized spin texture—have been theoretically predicted to annihilate with counterparts known as antiskyrmions. By means of electron microscopy, such annihilation has now been observed in a cubic chiral magnet.

Combinatorial optimization is one of the areas for which quantum computing promises to overcome classical devices. An experiment with arrays of Rydberg atoms now shows how to solve combinatorial graph problems with auxiliary atomic wires.

The LHCb Collaboration reports the observation of an exotic, narrow, tetraquark state that contains two charm quarks, an up antiquark and a down antiquark.

The flat portions of the band structure in bilayer graphene are shown to support interaction-driven symmetry-broken states, similar to moiré heterostructures.

Many-body open quantum systems are predicted to undergo a phase transition towards a pure state through frequent projective measurements. The phases separated by this transition have now been observed with random circuits on a trapped-ion computer.

Transport experiments highlight a technique to detect transitions in the topological state of two-dimensional materials, with possible applications in memory devices.

Unless you are nearby, it is difficult to verify where someone is. Access to a single qubit and classical computation and communication makes it possible to securely check someone’s position as long as adversaries’ quantum resources are limited.

Heat transport in electronic systems is influenced by nearby superconductors due to the so-called proximity effect. Combining this with the manipulation of superconductivity using magnetic fields enables the control of nanoscale thermal transport.

The presence or absence of a strange metal phase in twisted bilayer graphene has been controversial. Now, measurements over a wide range of temperature and doping give much stronger evidence for its existence.

Correlated insulating states are common in twisted bilayer graphene when the density of carriers is close to an integer per moiré unit cell. Now, such states emerge at half-integer fillings and show signs of being spin or charge density waves.

The nuclear spins of noble gases are isolated from sources of decoherence but also from external control fields. Optically addressable alkali-metal atoms can couple strongly to noble-gas spins, potentially providing a mechanism for coherent control.

Many nanophotonic devices rely on optical nonlinearities, which can be indirectly engineered. The quantum interference of different nonlinear pathways directly controls the Kerr nonlinearity without changing the device design.

The change in a band structure when a magnetic field is applied should depend on the momentum of the electronic state, but this is hard to measure. Now, this effect is demonstrated in a topological magnet.

The capabilities of optically accessible Rydberg levels are limited by their lifetime. An experiment demonstrates how to detect and manipulate long-lived circular states through the coupling of valence electrons in alkaline-earth Rydberg atoms.

The Mott metal-to-insulator transition plays a key role in theoretical studies of high-temperature superconductors. A mathematical analysis of the theory of metals identifies a renormalization-group fixed point describing Mott physics.

A spin glass is a disordered system with randomized competing magnetic interactions. Now, a metamaterial artificial spin glass based on nanomagnets is reported, with rudimentary features of a neural network.