Lattice defects on the toric code, like twists and punctures, can exhibit exotic behavior and have been suggested as viable building-block candidates for topological quantum computing. Here the authors build an encoding around a new defect, namely a mixed-boundary puncture. They show that this strategy allows for non-Abelian fusion and braiding properties reminiscent of Majorana exchange.

The authors design and implement a laser system using novel phase modulation and highly dispersive element techniques for realizing high-fidelity control over atomic hyperfine states, which are useful as qubits in quantum information processing. This approach is demonstrated in a neutral ${}^{87}$Rb atomic system and could also be applied to trapped-ion systems.

Studying out-of-equilibrium dynamics or quench dynamics in cold-atom systems has become a paradigm for studying phase transitions. In this paper, the authors experimentally study the relaxation dynamics of a trapped ultracold Bose gas cooled across the BEC threshold. They find, among other things, a delay in the onset of condensate formation depending on the collision rate of the gas and a universal condensate growth depending only on the cooling rate.

In an effort to better bridge quantum optics and strong-field physics, the authors demonstrate the ability of intense laser-atom interactions to generate coherent-state superpositions and tune their quantum properties. They show that these superpositions can transition from optical “cat” states to “kitten” states with a change in atomic density, and report the highest-photon-number optical cat state to date.

The authors report a theoretical study on the process of stimulated Compton scattering in the close-to-threshold ionization of the hydrogen molecule with x-ray attosecond radiation by solving the time-dependent Schrödinger equation with nondipole corrections. They show how to control and isolate the nondipole-induced nonlinear photoelectron emission by adjusting the x-ray laser parameters and molecular alignment.

Testing quantum mechanics against alternative theories must be done in a way that does not make assumptions about the validity of any particular theory, in particular, without presuming the correctness of quantum theory. Here, the authors set bounds on possible deviations from quantum theory using the formalism of Generalized Probabilistic Theories by experimentally probing a three-level system consisting of a photon shared among three modes. They find no evidence for the breakdown of quantum theory.

It may be naively assumed that certain entanglement measures, like the entanglement entropy of a pure state, approach zero in the classical limit. Here, however, the authors show that the limit is both well-behaved and nonzero: for a bipartite system of N particles, it coincides with the Shannon entropy of N bits. These results have been demonstrated previously in the context of quantum field theory, but here the authors use fully analytic methods to provide a general physical interpretation.

The authors present a joint experimental and theoretical study of the diffraction of a rubidium Bose-Einstein condensate by an optical lattice in the quasi-Bragg regime. The results focus on the diffraction losses and multiport features, which could guide the future studies of atom interferometry.

The authors experimentally demonstrate that, counterintuitively, the heralding of zero photons in an ancillary mode can reduce the mean photon number in an optical mode despite the fact that no photons have been removed from the system. This scheme finds an immediate application in the process of noiseless attenuation.

Multiplexing techniques could boost the chances of achieving end-to-end entanglement of a signal in a trapped-ion-based quantum-computer network.

Synopsis on:
Prajit Dhara et al.
Phys. Rev. A 105, 022623 (2022)

At the beginning of 2021, eight Physical Review journals began publishing Letters which are intended for the accelerated publication of important new results targeted to the specific readership of each journal.

We are very pleased to offer the readers of Physical Review a new, carefully curated collection of articles from the vibrant field of laser-plasma particle acceleration. Some of the articles have already been published, and others will be forthcoming. This Collection is the latest in the journal’s series of Special Collections on current or emerging fields and topics.

APS Editor in Chief, Michael Thoennessen, discusses a new opportunity for communicating authors to include their pronouns together with their contact email in order to promote a more respectful, inclusive, and equitable environment.

Physicists working in optics, atomic and molecular physics, and quantum information reflect on landmark papers and how they influence research today.

Special Feature in Physics