Research articles

Electrons in f orbitals can create localized states that interact strongly and drive strange metal and critical behaviour via the Kondo mechanism. Now a mechanism of geometric frustration enables similar phenomena with d electrons.

Time crystals spontaneously produce periodic oscillations that are robust to perturbations. A time crystal phase with a long coherence time has now been produced using the electron and nuclear spins of a semiconductor sample.

When applying sufficient strain, the flow of dense granular matter becomes critical. It is now shown that this state corresponds to random loose packing for spheres with different friction coefficients and that these packings can be mapped onto the frictionless hard-sphere system.

Dense suspensions are granular materials suspended in a liquid at high packing fractions, exhibiting high viscosity. The latter is now shown to be related to the formation of a network of rigid clusters at large shear stress.

High-precision photoemission measurements determine that the superconducting pairing symmetry in KFe₂As₂ is the same as in other types of iron-based superconductors, despite having different features in the band structure.

Inducing coherent interactions between distinct magnon modes—collective excitations of magnetic order—has been challenging. A canted antiferromagnet has demonstrated coherent magnon upconversion induced by terahertz laser pulses.

The mechanism of charge density wave formation has been hard to explain due to accompanying structural distortions. Now low-dimensional HfTe₂ is revealed to host a purely electronic exitonic charge density wave driven by reduced screening effects.

The transition from a metastable state to the ground state in classical many-body systems is mediated by bubble nucleation. This transition has now been experimentally observed in a quantum setting using coupled atomic superfluids.

Raman sideband cooling is a method used to prepare atoms and ions in their vibrational ground state. This technique has now been extended to molecules trapped in optical tweezer arrays.

The phase diagram of confined ice is different from that of bulk ice. Simulations now reveal several 2D ice phases and show how strong nuclear quantum effects result in rich proton dynamics in 2D confined ices.

The kernel method in machine learning can be implemented on near-term quantum computers. A 27-qubit device has now been used to solve learning problems using kernels that have the potential to be practically useful.

Light passing through complex media is subject to scattering processes that mix together different photonic modes. This complexity can be harnessed to implement quantum operations.

In quasi-crystals, constituents do not form spatially periodic patterns, but their structures still give rise to sharp diffraction patterns. Now, quasi-crystalline patterns are found in a system of spherical macroscopic grains vibrating on a substrate.

The dynamics of isolated quantum many-body systems far from equilibrium is the object of intense research. Magnetization measurements in a spinor atomic gas now offer a way to classify universal dynamics based on symmetry and topology.

Active flows in biological systems swirl. A coupling between active flows, elongated deformations and defect dynamics helps preserve self-organised structures against disordered swirling.

Non-Hermitian systems can be described in terms of gain and loss with a coupled environment—a hard feature to tune in quantum devices. Now an experiment shows non-Hermitian topology in a quantum Hall ring without relying on gain and loss.

Cell motion along linear confinements is deterministic. Now a model predicts deterministic oscillations in cellular polarization at a Y junction in a set-up with adhesive patterns.

Electric polarization is well defined for insulators but not for metals. Electric-like polarization is now realized via inhomogeneous lattice strain in metallic SrRuO₃, generating a pseudo-electric field. This field affects the material’s electronic bands.

Phases of matter can host different transport behaviours, ranging from diffusion to localization. Anomalous transport has now been observed in an interacting Bose gas in a one-dimensional lattice subject to a pulsed incommensurate potential.

Using the valley degree of freedom in analogy to spin to encode qubits could be advantageous as many of the known decoherence mechanisms do not apply. Now long relaxation times are demonstrated for valley qubits in bilayer graphene quantum dots.