image: Optica Quantum October issue.
Credit: Optica Publishing Group, Optica Quantum
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. October marks the one-year anniversary of Optica Quantum’s launch in 2023, acknowledged by the Editor-in-Chief and Deputy Editors in their commemorative editorial.
Summaries of the 10 research articles in the latest issue are provided below.
Ronen Shekel, Ohad Lib, and Yaron Bromberg, "Shaping entangled photons through arbitrary scattering media using an advanced wave beacon," Optica Quantum 2, 303-309 (2024). https://doi.org/10.1364/OPTICAQ.525445
Utilizing entangled photons in real-world applications is challenging, due to scattering and aberrations. To compensate for this effectively, a strong, classical feedback source is required. A novel feedback mechanism, based on Klyshko's advanced-wave picture is proposed and demonstrated.
Andrew Kolmer Forbes, Philip Daniel Blocher, and Ivan H. Deutsch, "Modeling local decoherence of a spin ensemble using a generalized Holstein–Primakoff mapping to a bosonic mode," Optica Quantum 2, 310-328 (2024).
https://doi.org/10.1364/OPTICAQ.528078
A new method represents the dynamics of local decoherence of spin ensembles in a bosonic mode by generalizing the Holstein-Primakoff mapping to include all permutationally symmetric states of the spin ensemble. It is further shown how one can use this method to more efficiently describe noisy dynamics of spins, and how to use the formalism to calculate quantities of interest like the quantum Fisher information.
Hari Kumar Yadalam, Matthias Kizmann, and Shaul Mukamel, "Ultrafast four-wave-mixing spectroscopy with two vacuum fields and coincidence-double-heterodyne detection," Optica Quantum 2, 330-338 (2024).
https://doi.org/10.1364/OPTICAQ.523848
The interpretation of ultrafast nonlinear wave mixing spectroscopic signals with classical light is complicated by their dependence on multiple light-matter interaction pathways. A quantum interferometric spectroscopy scheme employing coherent light pulses and vacuum modes in conjunction with coincidence detection is proposed to selectively probe a single perturbative pathway contributing to the photon-echo signal. Application to a Frenkel dimer demonstrates clear advantages over the corresponding classical signal.
Laura Serino, Werner Ridder, Abhinandan Bhattacharjee, Jano Gil-Lopez, Benjamin Brecht, and Christine Silberhorn, "Orchestrating time and color: a programmable source of high-dimensional entanglement," Optica Quantum 2, 339-345 (2024).
https://doi.org/10.1364/OPTICAQ.532334
Flexible control over entanglement dimensionality can facilitate practical implementations of high-dimensional quantum communication protocols, such as quantum key distribution, enabling highly efficient and secure communication. Such control is demonstrated by implementing a photon pair source that generates maximally entangled time-frequency states with programmable dimensionality from 1 to 20, based on a dispersion-engineered waveguide and spectral shaping of the pump pulse.
Gianvito Chiarella, Tobias Frank, Pau Farrera, and Gerhard Rempe, "Two-cavity-mediated photon-pair emission by one atom," Optica Quantum 2, 346-350 (2024).
https://doi.org/10.1364/OPTICAQ.529241
Photon-pair sources are widely used in quantum optics and quantum information experiments. An efficient photon-pair source consisting of a single atom coupled to two crossed optical fiber cavities is presented. It achieves an in-fiber photon-pair emission efficiency of 16% and study the properties of the emitted photons in different atom-cavity coupling regimes.
Dotan Halevi, Boaz Lubotzky, Kfir Sulimany, Eric G. Bowes, Jennifer A. Hollingsworth, Yaron Bromberg, and Ronen Rapaport, "High-dimensional quantum key distribution using orbital angular momentum of single photons from a colloidal quantum dot at room temperature," Optica Quantum 2, 351-357 (2024).
https://doi.org/10.1364/OPTICAQ.528214
High-dimensional quantum key distribution (HDQKD) offers improved key rates over traditional QKD, but has been limited by indeterministic photon sources. Full emulation of an HDQKD system is demonstrated using single colloidal giant quantum dots as a deterministic, compact, and room-temperature single-photon source. By encoding information in the orbital angular momentum of photons, the system achieves improved key rates compared to traditional QKD while maintaining comparable error rates, paving the way for practical, high-performance HDQKD systems.
Inbar Hurvitz, Anatoly Shukhin, Leonid Vidro, Hagai Eisenberg, and Ady Arie, "Phase analysis of biphoton joint spectra by interference between different SPDC sources," Optica Quantum 2, 358-364 (2024).
https://doi.org/10.1364/OPTICAQ.537375
This study introduces a method for phase-sensitive analysis of bi-photon joint spectral amplitudes (JSAs) by exploiting interference between two nonlinear photonic crystals. The approach enables direct access to phase information traditionally inaccessible via standard joint spectral intensity measurements, simplifying the reconstruction of quantum states. This technique has broad potential for developing advanced quantum technologies, such as quantum state manipulation, phase-sensitive measurements, and improved precision in quantum communication protocols.
A. Brzosko, R. I. Woodward, Y. S. Lo, M. Pittaluga, P. R. Smith, J. F. Dynes, and A. J. Shields, "Metro-scale QKD using multimode fiber," Optica Quantum 2, 365-370 (2024). https://doi.org/10.1364/OPTICAQ.534258
Multimode fiber (MMF) links are widely used in metropolitan-scale fiber networks. This demonstration of a proof-of-principle high-performance QKD protocol carried out over MMF at distances up to 17 km confirms their suitability for modern QKD system deployment, unlocking new opportunities for quantum applications using legacy fiber.
A. Miguel-Torcal, A. González-Tudela, F. J. García-Vidal, and A. I. Fernández-Domínguez, "Multiqubit quantum state preparation enabled by topology optimization," Optica Quantum 2, 371-378 (2024).
https://doi.org/10.1364/OPTICAQ.530865
Using a topology optimization procedure, inverse-designed nanophotonic cavities enable the preparation of pure states of pairs and triples of distant quantum emitters (Bell and W states, respectively). The devices involve moderate values of the dielectric constant, operate under continuous laser driving, and generate entanglement by tailoring both the coupling between the emitters and their decay. These findings open the way towards the efficient and fast preparation of multiqubit quantum states with engineered features.
Cameron Simmons, Peter Barrow and Ross Donaldson, “Dawn and dusk satellite quantum key distribution using time- and phase-based encoding and polarization filtering,” Optica Quantum 2, 381-389 (2024).
https://doi.org/10.1364/OpticaQ.527880
The scattering that produces daylight causes partial polarization, which is greatest perpendicular to the sun. Existing technology can be leveraged to filter by polarization, providing significant reductions in background light. Time and phase encoded satellite quantum key distribution benefits from polarization filtering, particularly at dawn and dusk, expanding the window in which it can operate.
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