Letters in 2019

Three-dimensional spin–orbit coupling is synthesized for ultracold fermions trapped in optical Raman lattice. The band structure bearing a nodal-line semimetal character is reconstructed through a series measurement of spin textures.

High harmonics are generated from a thin film by leveraging the epsilon-near-zero effect. These kinds of harmonic are found to exhibit a pronounced spectral redshift as well as linewidth broadening caused by the time-dependency of this effect.

Disorder present in monolayer NbSe₂ is found to be able to enhance its superconductivity. A systematic study reveals the origin—disorder-induced multifractality of the electron wavefunctions strengthens the local interactions.

The authors predict that Berry flux can be spontaneously generated in a metal by plasmonic oscillations in response to illumination by light. They show that this topological ‘Berryogenesis’ can work in graphene.

Experiments report the generation and manipulation of eight photons on a silicon chip. Integrating linear and nonlinear photonic circuitry, three different boson sampling approaches are implemented and used to compute molecular vibronic spectra.

The authors demonstrate that individual atoms on a surface can be detected and distinguished from each other with subångström resolution using the electron spin resonance.

Quantum gas microscopes provide high-resolution real-space snapshots of quantum many-body systems. Now machine-learning techniques are used in choosing theoretical descriptions according to the consistency of their predictions with these snapshots.

Machine learning can help to identify quantum phase transitions. Here a trained neural network is applied to single-shot density images from a quantum gas experiment, realizing the Haldane model and the Bose–Hubbard model.

A prediction of the existence of trapped acoustic-gravity waves in stratified fluids provides a platform for probing topological phenomena in the lab—with possible implications for astrophysical and geophysical flows.

It is shown that composite fermions in the fractional quantum Hall regime form paired states in double-layer graphene. Pairing between layers gives a phase similar to an exciton condensate and pairing within a layer may lead to non-abelian states.

Transport data reveal interlayer composite fermion fractional quantum Hall states in double-layer graphene. The authors also show that these can pair up to form an interlayer composite fermion exciton condensate.

A Josephson junction array is used to show the phase mode associated with superconductivity surviving deep in the insulating regime at high frequency. This generates a device with an effective fine structure constant larger than unity.

Strong quantum correlations in an ultracoherent optomechanical system are used to demonstrate a displacement sensitivity that is below the standard quantum limit.

The Kondo effect—the screening of a magnetic impurity’s local moment by the electron Fermi sea in a metal—has been observed in a charge-insulating quantum spin liquid material, where the spinon excitations take the role of electrons.

According to the Unruh effect, for an accelerating observer the vacuum is filled with thermal radiation. Experiments now simulate this effect, recreating the statistics of Unruh radiation in the matter-wave field of a Bose–Einstein condensate.

This study presents a proposal for an all-optical method for manipulating chiral superconductors. Light pulses can switch the handedness of the chirality, potentially enabling controlled local writing of domain walls and associated Majorana modes.

A collective excitation behaving as a single emergent entity, known as a quasiparticle, often becomes unstable when encountering a continuum of many-body excited states. However, under certain conditions, the result can be totally different.

Colloidal clusters are shown to undergo directional locking when driven across a patterned surface. The role of the Fourier components of the particle–surface interaction suggests a means of leveraging this behaviour for nanoscale manipulation.

The decay asymmetry and helicity phase of polarized baryon–antibaryon pairs are measured at the BESIII experiment, testing charge–parity symmetry and revealing a discrepancy of the Λ → pπ⁻ decay asymmetry with respect to the current world average.

AlPt is shown to be a chiral topological material with four-fold and six-fold degeneracies in the band structure. Fermi arc edge states span the whole Brillouin zone and their dispersion enables identification of the handedness of the chiral material.