PERSPECTIVE
The authors offer an overview of progress and a future perspective of large-scale optical quantum entanglement. They cover a broad range of topics from the basics of continuous-variable optical quantum entanglement and a multiplexing methodology for the generation of large-scale quantum entanglement to future approaches toward practical usages of large-scale optical quantum entanglement. The content includes both pedagogical content and the search for future directions beyond the current frontier.
Warit Asavanant and Akira Furusawa
Phys. Rev. A 109, 040101 (2024)
LETTER
The authors theoretically describe the stabilization of crystalline structures in interaction-driven Bose-Einstein condensates by analytically deriving a complex-valued Ginzburg-Landau equation for pattern formation. The resulting equation captures the competition between linear instability induced by the drive and nonlinear suppression induced by interactions and, in agreement with recent experiments, explains the emergence of square grid density patterns as stable states.
Keisuke Fujii et al.
Phys. Rev. A 109, L051301 (2024)
EDITORS' SUGGESTION
Boson sampling is a promising candidate for showcasing quantum advantage. However, achieving this advantage involves pinpointing the optimal balance between shallow-depth circuits, which are susceptible to classical simulation, and larger-depth circuits prone to noise. Here, the authors introduce a linear-optical circuit design with nonlocal gates, aimed at enhancing the probability of demonstrating advantage even with shallow circuit depths.
Byeongseon Go, Changhun Oh, Liang Jiang, and Hyunseok Jeong
Phys. Rev. A 109, 052613 (2024)
EDITORS' SUGGESTION
In an open system, environment-induced synchronization can occur between the expectation values of spin observables of a pair of qubits. Here, the authors apply a machine learning method to predict the emergence of such synchronization.
F. Mahlow et al.
Phys. Rev. A 109, 052411 (2024)
LETTER
In the context of cavity optomechanics in the strong-coupling regime, the authors present a method for generating nonclassical motional states of a mechanical resonator. The states’ nonclassical nature, which is manifested by a strongly negative Wigner function, is found to be due to the interplay between the intrinsically nonlinear optomechanical interaction and the laser drive applied to the cavity.
Jonathan L. Wise, Clément Dutreix, and Fabio Pistolesi
Phys. Rev. A 109, L051501 (2024)
LETTER
The authors investigate whether nonequilibrium environments can promote localization rather than destabilize it. By studying the impact of quantum jumps on the localization transition in driven-dissipative systems, the authors reveal pathways to enhance localized regimes using simple yet realistic postselection schemes.
Sparsh Gupta, Hari Kumar Yadalam, Manas Kulkarni, and Camille Aron
Phys. Rev. A 109, L050201 (2024)
LETTER
Not all entanglement is distillable, i.e., extractable in pure form. In this work, the authors show that being assisted by catalysts, which generally can help transform quantum states, is not enough to change this; certain entangled states will stay “bound entangled” even when catalysts are allowed.
Ludovico Lami, Bartosz Regula, and Alexander Streltsov
Phys. Rev. A 109, L050401 (2024)
EDITORS' SUGGESTION
The authors investigate the thermodynamic properties of a two-dimensional dilute Bose-Fermi mixture of ultracold atoms at zero temperature through two complementary methods: perturbation theory to the second order in the interactions and quantum Monte Carlo. They find good agreement between analytic expressions and numerical results for weak interactions, while significant discrepancies appear in the regime close to mechanical instability, indicating phase separation of the bosonic component.
Jacopo D'Alberto et al.
Phys. Rev. A 109, 053302 (2024)
LETTER
The authors perform spin-noise spectroscopy on an unpolarized Rb vapor in the spin-exchange-relaxation-free regime and observe noise spectral distributions that deviate strongly from Lorentzian models that accurately describe lower-density regimes. This observation shows that new kinds of information can be extracted from noise spectra and may improve atomic vapor sensors.
K. Mouloudakis et al.
Phys. Rev. A 109, L040802 (2024)
LETTER
This work focuses on enhancing the dispersive readout of a single electron spin qubit by utilizing displaced squeezed vacuum states for the probe photons. The built-in quantum correlations of squeezed photons lead to significant improvements in qubit readout fidelity and speed.
Chon-Fai Kam and Xuedong Hu
Phys. Rev. A 109, L040402 (2024)
LETTER
The authors investigate the nonequilibrium dynamics of the order parameter of a fermionic condensate following an abrupt change in the pairing interaction at nonzero temperature. They express the magnitude of the resulting oscillations with Tan’s contact, and identify strong thermal effects as the temperature approaches the critical value, in particular for the nonlinear evolution which follows deep quenches.
H. Kurkjian et al.
Phys. Rev. A 109, L041302 (2024)
EDITORS' SUGGESTION
The authors theoretically analyze the performance of long-distance quantum communication protocols, specifically quantum repeaters based on Gottesman-Kitaev-Preskill (GKP) qudits. Previously, only the qubit case has been studied. They construct three quantum repeater schemes and find that, while in most cases any benefits of using higher dimensions is negated by worse error correction, there are some regimes where the use of qudits does increase the secret key rate.
Frank Schmidt, Daniel Miller, and Peter van Loock
Phys. Rev. A 109, 042427 (2024)
LETTER
The authors establish a connection between nonstabilizerness and a readily measurable property – the entanglement spectrum. This connection not only provides a deeper understanding of quantum complexity but also offers a practical way to probe nonstabilizerness even in noisy environments.
Emanuele Tirrito et al.
Phys. Rev. A 109, L040401 (2024)
