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
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)
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 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)
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)
LETTER
Many-body theory is used to study positron binding in halogenated hydrocarbons . As well as reproducing recent experimental binding energies, the general effect of halogenation is discussed and explained: fluorinated molecules generate a weaker positron-molecule correlation potential than their chlorinated and brominated counterparts owing to fluorinated molecules having higher molecular orbital ionization energies and a lower density of electron states near the highest occupied molecular orbitals.
J. P. Cassidy et al.
Phys. Rev. A 109, L040801 (2024)
LETTER
In a parity-time (PT) symmetric photonic dimer structure, the authors analytically obtained the phase diagram with quantum jumps induced by loss and gain, defined a Hermitian exchange operator to characterize different PT phases, and engineered the quantum state and Hong-Ou-Mandel interferences. Their study paves the way for quantum state engineering, quantum interferences, and logic operations in non-Hermitian photonic systems.
Xinchen Zhang et al.
Phys. Rev. A 109, L041503 (2024)
LETTER
The authors show that a resonator designed to operate at an absorbing exceptional point is substantially better at capturing a naturally emitted decaying waveform than a conventional cavity with a similar factor. This enhanced performance can lead to improved protocols for classical and quantum state transfer between resonant cavities.
Asaf Farhi et al.
Phys. Rev. A 109, L041502 (2024)
EDITORS' SUGGESTION
The authors study the interaction between two polar molecules in rotational states differing by two or more quanta. They find that the resultant repulsive van der Waals interaction can potentially suppress collisional losses at low temperatures.
Etienne F. Walraven and Tijs Karman
Phys. Rev. A 109, 043310 (2024)
LETTER
The authors derive bounds on the suppression of the bandwidth-integrated local density of states (LDOS). They show that effective one-dimensional gratings which support a slow light mode can achieve near-perfect LDOS suppression even in the presence of material loss.
Benjamin Strekha et al.
Phys. Rev. A 109, L041501 (2024)
