EDITORS' SUGGESTION
Controlled engineering of vortex-pinning sites in cuprate superconductors is a pivotal goal in manufacturing devices based on magnetic flux quanta. This study employs focused helium-ion beams to create ultradense hexagonal arrays of defects in YBaCuO thin films, achieving lattice spacings as small as 20 nm. Efficient pinning by a remarkably high matching field of 6 T is observed from the critical temperature down to 2 K. This research expands the range of temperatures and magnetic fields for exploring vortex matter using regular artificial vortex-pinning landscapes.
Max Karrer et al.
Phys. Rev. Applied 22, 014043 (2024)
EDITORS' SUGGESTION
In quantum information science, online Hamiltonian learning emerges as a promising tool to compensate for uncontrolled environmental effects, thereby enhancing qubit quality factors. Several estimation schemes have been proposed to boost learning efficiency, but experimental implementation has been hindered by hardware limitations. Here the authors perform physics-informed, adaptive Bayesian Hamiltonian estimation for a singlet-triplet spin qubit, using a quantum controller powered by a field-programmable gate array. These techniques allow for significantly faster and more accurate real-time tracking of low-frequency noise in solid-state qubits.
Fabrizio Berritta et al.
Phys. Rev. Applied 22, 014033 (2024)
EDITORS' SUGGESTION
Despite being formidable tools in artificial intelligence, artificial neural networks consume substantial energy during their training phase. This study introduces hardware-based artificial neural networks that utilize artificial and natural noncollinear spin textures, significantly reducing energy consumption and enhancing operational efficiency. The authors demonstrate two such spin-texture-based physical reservoirs, which exhibit robust information-processing capabilities in two nonlinear benchmark tests. Additionally, they implement a direct-feedback-alignment algorithm within hardware, further advancing the efficiency of deep neural networks.
Haotian Li et al.
Phys. Rev. Applied 22, 014027 (2024)
EDITORS' SUGGESTION
Measuring the local density of states (LDOS) in continuous systems poses substantial challenges. By leveraging the Purcell effect in an elastic wave lattice, the authors achieve discrete, contactless measurements of the LDOS. This study further analyzes the distribution of fractional LDOS across various disclination structures. This method illuminates the exploration of bulk topology by examining LDOS localized at edges or within disclinations. The findings bear promising implications for characterizing topological phases and enhancing control of structural vibration.
Meng-Yang Liu et al.
Phys. Rev. Applied 22, 014025 (2024)
EDITORS' SUGGESTION
Recent theoretical developments have demonstrated that the optimal field profile for coupling circular apertures within the Fresnel zone is a generalized cylindrical vector beam (CVB), composed of Bessel beams with different complex weights. However, there has not been a systematic method to generate such generalized CVBs. This study uses mode-converting metasurfaces to control the modal distribution within a cylindrical cavity to generate generalized CVBs, a milestone in the development of next-generation wireless power transfer operating in the Fresnel zone. Furthermore, this method allows exploration of CVBs that can be optimized and tailored for specific applications or functions.
Faris Alsolamy and Anthony Grbic
Phys. Rev. Applied 22, 014001 (2024)
LETTER
This study employs a non-Hermitian process that effectively balances coherent and dissipative channels, ensuring the unidirectional transfer of photonic qubits. The significance of this approach lies in its applicability to unidirectional routing in both the classical and quantum domains, which is currently challenging to achieve in the synthesis of qubit unidirectional routers and spin-wave diodes. Additionally, this system’s fully optical tunable properties can reverse the direction of qubit transfer. This scheme is expected to greatly impact the design of unidirectional devices in quantum communication and information processing.
En-Ze Li et al.
Phys. Rev. Applied 21, L061002 (2024)
EDITORS' SUGGESTION
Optical phase determination using just a few photons is crucial for applications in biological imaging and quantum information processing, yet is hampered by shot noise from the source and readout noise from the sensor. Employing a skipper CCD, which can arbitrarily decrease readout noise, the authors investigate these noise sources individually and demonstrate a significant improvement in detection fidelity with reduced detector noise. With fewer than three photons per pixel, the accuracy of phase estimation suffers, regardless of detection noise. This insight highlights the skipper CCD’s potential to enhance high-fidelity phase detection in ultralow-light scenarios.
Q. Pears Stefano et al.
Phys. Rev. Applied 21, 064050 (2024)
EDITORS' SUGGESTION
The authors demonstrate all-optical modulation on a chip, which is important for scalable all-optical information processing and quantum computing, as it supports fan-out and cascaded operations. Using quantum Zeno blockade, logical operations are realized in an interaction-free manner, solely through parametric nonlinear optics. This scheme can thus be implemented at room temperature and on highly integrated chips, as opposed to approaches using single emitters, where cryogenic cooling is required.
Zhan Li et al.
Phys. Rev. Applied 21, 064049 (2024)
EDITORS' SUGGESTION
Diamond-based nitrogen-vacancy (N-) centers hold the potential to overcome the sensor limitations for magnetocardiography (MCG), but their invasive measurement scheme is incompatible with clinical settings. This study presents a noninvasive diamond MCG system based on N- center ensembles enhanced by techniques such as magnetic flux concentration, and demonstrates a practical instance of noninvasive MCG measurement on a living animal. These results mark a substantial step toward deploying diamond MCG in biophysical applications, highlighting its future potential in biomagnetic observations.
Ziyun Yu et al.
Phys. Rev. Applied 21, 064028 (2024)
