Articles in 2021

High-precision mass measurements of exotic zirconium nuclei are reported, and reveal a double-shell closure for the deformed nucleus ⁸⁰Zr, which is more strongly bound than previously thought.

A search for axion-like dark matter with a quantum sensor that enhances potential signals is reported. This work constrains the parameter space of different interactions between nucleons and axion-like particles and between nucleons and dark photons.

Active fluids exhibit properties reminiscent of equilibrium systems when their degrees of freedom are statistically decoupled. A theory for the fluctuating hydrodynamics of these fluids offers a probe of their anomalous transport coefficients.

Scanning tunnelling microscopy provides evidence for topological superconductivity in a naturally occurring transition metal dichalcogenide material.

Current quantum computers do not have error correction, which means noise may prevent them outperforming classical devices in useful tasks. An analysis of quantum optimization shows that current noise levels are too high to produce a quantum advantage.

The cell cortex stiffens during cell division, facilitating the necessary shape changes. Microrheology measurements now reveal that the rest of the cell interior actually softens, in a process that probably involves two key biomolecules trading roles.

A state that breaks time-reversal symmetry is observed in the normal phase above the superconducting critical temperature in a multiband superconductor. This could be explained by correlations between the Cooper pairs formed in different bands.

Atoms in a semiconductor can have non-zero nuclear spins, creating a large ensemble with many quantum degrees of freedom. An electron spin coupled to the nuclei of a semiconductor quantum dot can witness the creation of entanglement within the ensemble.

Measurements of the phase diagram of water reveal first-order phase transitions to face- and body-centred cubic superionic ice phases. The former is suggested to be present in the interior of ice giant planets.

Quantum networks require a connection between quantum memories and optical links, which often operate in different frequency ranges. An optomechanical device exploiting the strain dependence of a colour-centre spin provides such a spin–optics interface at room temperature.

Entangled photon states can be used to make quantum information more robust. A photonic experimental implementation with eight qubits shows that error-protection schemes can increase the success rate of running a quantum algorithm.

Moiré potentials substantially alter the electronic properties of twisted bilayer graphene at a magic twist angle. A propagating plasmon mode, which can be observed with optical nano-imaging, is associated with transitions between the moiré minibands.

Superionic water is believed to exist in the interior of ice giant planets. By combining machine learning and free-energy methods, the phase behaviours of water at the extreme pressures and temperatures prevalent in such planets are predicted.

Non-Abelian topology allows topological charges in multi-gap systems to be converted by braiding of different band nodes. Such multi-gap effects are experimentally observed in an acoustic semimetal.

The hyperfine states of ultracold polar molecules are a strong candidate for storing quantum information. Identifying and eliminating all detectable causes of decoherence has extended the qubit coherence time beyond 5.6 s in RbCs molecules.

Realizing the potential of dipolar molecular gases to explore quantum physics needs elastic, tunable interactions and low temperatures. This is now possible due to advances in control that suppress molecular losses and enable efficient cooling.

Some quantum spin liquids are expected to have an effective Fermi surface of fractionalized spinon excitations. The two-dimensional spin liquid candidate 1T-TaSe₂ has charge density modulations that may be caused by an unstable spinon Fermi surface.

Proton acceleration by a super-critical collisionless shock is observed in laboratory experiments, and numerical simulations suggest shock surfing as the underlying acceleration mechanism.

Optical frequency combs are a key technology in precision time keeping, spectroscopy and metrology. A theoretical proposal shows that introducing topological principles into their design makes on-chip combs more efficient and robust against fabrication defects.

Frictional motion between two surfaces in contact starts with the formation of nucleating rupture fronts. It is now shown that these emerge from nucleation fronts, which develop from a certain stress level onwards and with a characteristic velocity.