Volume 15 Issue 12, December 2019

High-magnetic-field experiments on the recently discovered unconventional superconductor UTe₂ are consistent with p-wave pairing arising while time-reversal symmetry is broken. In turn, this suggests that this material is a candidate for a chiral superconductor that may be exploited for topological quantum computing.

An unusual flavour of critical phenomena with a stable quantum critical phase of matter is observed in a strongly correlated material and linked to the underlying lattice structure.

Non-Hermitian systems with gain and loss give rise to exceptional points with exceptional properties. An experiment with superconducting qubits now offers a first step towards studying these singularities in the quantum domain.

This Perspective argues that ergodicity — a foundational concept in equilibrium statistical physics — is wrongly assumed in much of the quantitative economics literature. By asking the extent to which dynamical problems can be replaced by probabilistic ones, many economics puzzles are resolved in a natural and empirically testable fashion.

Experiments with two counter-propagating laser beams report the observation that the photon momentum is shared between the electron and parent ion in strong-field ionization, which results from the photon’s magnetic field acting on the electron.

The Kibble–Zurek mechanism, that is, the spontaneous formation of topological defects in a system crossing a continuous phase transition, is observed in a strongly interacting Fermi gas, where the underlying symmetry plays a crucial role.

The dynamics of a single dissipative qubit undergoing non-Hermitian quantum dynamics in the vicinity of an exceptional point is experimentally studied in a superconducting transmon circuit.

Conventional on-axis electron energy-loss spectroscopy can detect vibrational modes in crystals and amorphous solids at atomic resolution by isolating the specific signal from the background signal and the dipole contributions.

Matter-wave interference experiments demonstrate quantum superposition of molecules consisting of up to 2,000 atoms—the heaviest objects to show this quantum behaviour to date. This provides a bound on potential modifications to quantum mechanics.

The predicted metallization of hydrogen has long fascinated high-pressure physicists. Conductivity and spectroscopic measurements now reveal that above pressures of 350 GPa, hydrogen starts to conduct in a manner akin to a semimetal.

The recently discovered spin-triplet superconductor UTe₂ is found to display a number of other ‘re-entrant’ superconducting phases under ultrahigh magnetic fields.

Few-layer magnetic materials sometimes show a different form of magnetism from their thicker equivalents. The authors contend that the mechanism is changes in the stacking order in the thin limit that modify the interlayer exchange interaction.

A phase of quantum-critical behaviour is observed in a kagome lattice material. This arises from the interplay of strong interactions between electrons, and the frustration that arises both from the interactions and the lattice geometry.

Spin-polarized tunnelling data show that the breakdown of antiferromagnetic order and the collapse of the spectral gap are not correlated in Sr₂IrO₄. This indicates that short-range magnetic correlations are not behind the emergence of the pseudogap.

A quantum circuit-based algorithm inspired by convolutional neural networks is shown to successfully perform quantum phase recognition and devise quantum error correcting codes when applied to arbitrary input quantum states.

X-ray pump–probe experiments reveal that the molecular structure of C₆₀ molecules substantially delays their fragmentation following photoionization. This may help to understand X-ray laser-induced radiation damage on molecules.

Vacuum fluctuations in the vicinity of nanophotonic structures can lead to the conversion of a free electron into a polariton and a high-energy photon, whose frequency can be controlled by the electromagnetic properties of the nanostructure.

The remarkably large thermal Hall response recently observed in the copper oxides challenges our understanding of the excitations in an insulating antiferromagnet. Here, a possible explanation of the underlying physics is provided.

In a model system crosslinked by motors, cytoskeletal polymers slide past each other at speeds independent of their polarity. This behaviour is best described within an active-gel framework that deviates from the dilute limit set by existing theory.

Tell Bartolo Luque and Fernando Ballesteros how far the Sun is from the Earth, and they will tell you the size of the Universe.