WASHINGTON—The new issue of Optica Quantum is available. A Gold Open Access journal from Optica Publishing Group, Optica Quantum provides a home for high-impact research in quantum information science and technology enabled by optics and photonics.
Summaries of the 10 research articles in the latest issue are provided below.
Takuma Nakamura, Dahyeon Lee, Jason Horng, Florent Lecocq, John Teufel, and Franklyn Quinlan, "Cryogenic photonic link using an extended-InGaAs photodiode and short pulse illumination towards high-fidelity drive of superconducting qubits," Optica Quantum 3, 221-227 (2025).
https://doi.org/10.1364/OpticaQ.546795
Optical interconnects offer a path towards drive and readout of large numbers of superconducting qubits. High-speed extended-InGaAs detectors combined with short pulse detection can improve fidelity while reducing heat load.
Dong Beom Kim, Xiye Hu, Alfred B. U'ren, Karina Garay-Palmett, and Virginia O. Lorenz, "Spatio-spectral quantum state estimation of photon pairs from optical fiber using stimulated emission," Optica Quantum 3, 228-237 (2025).
https://doi.org/10.1364/OpticaQ.547491
This work demonstrates an optical fiber-based photon-pair source programmed to control the spatial-spectral correlations of generated photons, along with a new way of estimating quantum states in the spatial domain using stimulated emission. These advances streamline the process of measuring and optimizing the quantum state, reveal parity birefringence dispersion in fiber, and offer insights for developing future high-dimensional entangled photon sources.
Akitada Sakurai, Aoi Hayashi, William John Munro, and Kae Nemoto, "Quantum optical reservoir computing powered by boson sampling," Optica Quantum 3, 238-245 (2025).
https://doi.org/10.1364/OpticaQ.541432
Zhenghao Li, Matthew J.H. Kendall, Gerard J. Machado, Ruidi Zhu, Ewan Mer, Hao Zhan, Aonan Zhang, Shang Yu, Ian A. Walmsley, and Raj B. Patel, "Boosting photon-number-resolved detection rates of transition-edge sensors by machine learning," Optica Quantum 3, 246-255 (2025).
https://doi.org/10.1364/OpticaQ.555325
Machine learning-based signal processing algorithms allow transition-edge sensors (TESs)—highly sensitive photon-number resolving (PNR) detectors—to operate with near-unity efficiency, ultra-low dark count rates, and large dynamic range. Higher PNR detection rates could speed up quantum computing and quantum communication, and also enable quicker and more precise measurements in fields like bio-imaging and astronomy.
Lida Zhang, Fan Yang, Klaus Mølmer, and Thomas Poh, "Unidirectional quantum-optical elements for waveguide-QED with subwavelength Rydberg-atom arrays in free space," Optica Quantum 3, 256-268 (2025).
https://doi.org/10.1364/OpticaQ.545710
A two-dimensional subwavelength atomic array with Rydberg-Rydberg interaction is proposed to achieve near-perfect unidirectional light–matter coupling and subsequent realization of versatile nonlinear optical elements based on different interferometric setups in free space. Such nonlinear optical elements are exploited to deterministically generate tunable single photons and implement two-photon logical operations with near-unity fidelity.
Alessandra Gatti, Matteo Clerici, and Lucia Caspani, "Enhancing upconversion with space-time entanglement: from twin photons to twin-beams," Optica Quantum 3, 269-279 (2025).
https://doi.org/10.1364/OpticaQ.554539
Spatial and temporal entanglement in parametric down-conversion can enhance the efficiency of second harmonic generation, outperforming classical illumination even in regimes with many photons per mode. This work demonstrates that quantum advantages in upconversion persist well beyond the single-photon regime, offering practical pathways for optimizing nonlinear optical processes with entangled light sources.
Xiao Liu, Daniel I. Shahar, Dong Beom Kim, Virginia O. Lorenz and Siddharth Ramachandran, "Generation and engineering of orbital angular momentum biphotons in optical fibers," Optica Quantum 3, 280-288 (2025).
https://doi.org/10.1364/OpticaQ.560642
Direct generation of photon pairs carrying orbital angular momentum in ring-core fibers offers a fiber-based quantum source solution. This low-noise photon-pair source features a large coincidence-to-accidental ratio with highly engineerable spectral and spatial properties, and can pave the way for future high-dimensional entanglement in quantum communication and scalable quantum information processing.
N. Coste, D. A. Fioretto, S. E. Thomas, S. C. Wein, H. Ollivier, I. Maillette de Buy Wenniger, A. Henry, N. Belabas, A. Harouri, A. Lemaitre, I. Sagnes, N. Somaschi, O. Krebs, L. Lanco and P. Senellart, "Deterministic and efficient source of frequency-polarization hyper-encoded photonic qubits," Optica Quantum 3, 289-294 (2025).
https://doi.org/10.1364/OpticaQ.545703
Deterministic generation of photonic qubits hyper-encoded in frequency and polarization is achieved using a semiconductor quantum dot in a cavity. This approach brings the advantages of quantum dot sources to the field of quantum information processing based on frequency encoding.
Zongfeng Li, Yisheng Lei, Trevor Kling and Mahdi Hosseini, "Efficient storage of multidimensional telecom photons in a solid-state quantum memory," Optica Quantum 3, 295-302 (2025).
https://doi.org/10.1364/OpticaQ.564321
Solid-state quantum memories operating at telecom wavelengths are critical for multiplexed quantum optical communication and computation. An efficient optical pumping technique is demonstrated, enhancing the storage efficiency of erbium-doped crystal memories by more than an order of magnitude under moderate temperature and magnetic field conditions. High-fidelity multidimensional qubit storage is also achieved on this platform.
Gamze Gül, Gregory S. Kanter, Shannon G. Tan, Mehmet Berkay On, Roberto Proietti, S. J. Ben Yoo and Prem Kumar, "Noise impact of classical headers on the quantum payload in quantum wrapper networking," Optica Quantum 3, 303-311 (2025).
https://doi.org/10.1364/OpticaQ.564321
Quantum Wrapper Networking (QWN) enables control and monitoring of quantum information by wrapping quantum payloads with classical bits. This study shows that noise from classical light in fiber has negligible effect on polarization-entangled photon pairs over a 48 km fiber link, supporting QWN's scalability future quantum information networks.
