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Ultrafast NbN superconducting single-photon detector integrated in a parabolic mirror
Superconductor Science and Technology. 2025. Vol. 38. No. 10. Article 105009.
This work describes research and development of a superconducting nanowire single-photon detector (SNSPD) integrated with a parabolic mirror fabricated in a silicon wafer by focused ion beam etching. Using finite-difference time-domain simulations of the electromagnetic field distribution within the mirror and on its surface, the geometry of the molybdenum mirror was designed for efficient collection of light into a 1.5 µm spot. Reduction of the area of the SNSPD to 1.5 µm × 1.5 µm resulted in low kinetic inductance and faster operation. Although the detector response is currently limited by the 1 GHz band of the read-out electronics, the simulation suggests reduction of the detector dead time to 348 ps.
Войтович В. И., Makhov I., Мельниченко И. А. et al., Optics Letters 2026 Vol. 51 No. 17 P. 4872–4875
The influence of cavity surface passivation with SiO2 coating deposited by the plasma-enhanced chemical vapor deposition technique is investigated for injection microdisk lasers with an InGaAsN/GaAs quantum well active region. The electroluminescence spectra of the microdisk lasers with cavity diameters ranging from 12 to 32 μm with and without sidewall surface passivation were studied for a ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Оптика и спектроскопия 2026 Т. 134 № 3 С. 272–277
Представлены результаты по реализации генерации при повышенных температурах в лазерах с длиной волны генерации 980 nm на основе вертикального микрорезонатора с использованием непоглощающих на длине волны оптической накачки зеркал. Минимальная пороговая мощность накачки составила ~0.8 mW и соответствовала температуре 150 K. Добротность микрорезонатора, определенная на пороге генерации, превысила 13000. Максимальная рабочая температура микролазера составила 195 ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2026 Т. 52 № 12 С. 40–43
Реализована одночастотная генерация при 300 K в лазерах на основе вертикального микрорезонатора. Для лазеров с полупроводниковым выводным зеркалом пороговая плотность мощности накачки составила 6.5 kW/cm2. Добротность микрорезонатора и длина волны излучения, определенные на пороге генерации, равнялись 8800 и ~ 959.8 nm. Применение конструкции микрорезонатора с гибридным выводным зеркалом позволило повысить добротность микрорезонатора (до 12 360) ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2026 Т. 52 № 18 С. 30–34
Представлены результаты реализации генерации при комнатной температуре в планарных вертикальных микрорезонаторах на основе зеркал Al0.2Ga0.8As/Al0.9Ga0.1As. При 300 K пороговая плотность мощности и добротность на пороге генерации составили 11.4± 0.7 kW/cm2 и 5070± 160 соответственно. Двукратное превышение порога генерации привело к увеличению добротности микрорезонатора до 19 000. Эффективный латеральный теплоотвод подтвержден малым сдвигом энергии кванта, который составил ...
Added: September 25, 2026
Budkov Y., Kiselev M. G., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124508
We develop a three-mode statistical-mechanical theory for a two-conformer
solute in a near-critical solvent. A compressible lattice model with
vacancies yields the Gaussian free-energy functional for a critical conserved
density, an orthogonal noncritical conserved mode, and the local conformer
fraction. Their couplings follow from packing and cohesive interactions,
rather than being introduced phenomenologically. Kawasaki transport of the
two conserved fields and ...
Added: September 24, 2026
Kryzhanovskaya N., Makhov I., Dragunova A., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2026 Vol. 19 No. 1.1 P. 98–104
The planar microcavity structure was grown using molecular-beam epitaxy.
Single-mode lasing was observed at a wavelength of 960 nm for pillars with a diameter of
15 μm. At 300 K, the lasing threshold was approximately 30 mW. Increasing the pump
power to 2.7 times the threshold power resulted in a mode energy shift of approximately
1 meV. This shift ...
Added: September 23, 2026
Andreeva S., Gavrilov A. A., Dzhikirba K. R. et al., Physical Review B: Condensed Matter and Materials Physics 2026 Vol. 114 Article 134515
We examine plasma excitations with linear dispersion in a system of superconducting electrons in thin
NbN disks. Using frequency-domain terahertz spectroscopy, we study the evolution of plasmons up to critical
temperature Tc. The observed excitations tend to shift to the lower frequencies while temperature is increasing
and the spectral features vanish at T > Tc. We study the ...
Added: September 23, 2026
Образцова А. А., Ivanov K., Moiseev E. et al., Journal of Physics D: Applied Physics 2026 Vol. 59 No. 30 P. 305103
We demonstrate a thermo-optically tunable microlaser based on an InGaAs/GaAs quantum-dot (QD) active region employing a deformed limaçon-shaped cavity. The asymmetric geometry effectively lifts the degeneracy of high-Q whispering-gallery modes, enabling single-mode lasing. A side-mode suppression ratio exceeds 25 dB over a wide current range. Under continuous-wave electrical pumping, the device achieves a peak output power ...
Added: September 23, 2026
Budkov Y., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124105
Exact theories of electrolyte structure must satisfy the nonlocal constraints imposed by electrostatic screening, yet these constraints are most commonly formulated only for homogeneous bulk systems and at the level of two-point correlations. Here, we develop a unified field-theoretic framework that extends them to general inhomogeneous ionic fluids and nonlinear charge correlations. Using a standard ...
Added: September 22, 2026
Боровицкая И. В., Пименов В. Н., Коршунов С. Н. et al., Перспективные материалы 2026 № 10 С. 37–54
Проведено сравнение, обобщение и систематизация механизмов эрозии и разрушения
поверхности малоактивируемых материалов, перспективных для использования в
качестве материалов вакуумной камеры термоядерных реакторов: ванадия, его сплава
V – 10 Ti – 6 Cr – 0,05 Zr – 0,1 Si и вольфрама при последовательном воздействии на
них ионных и тепловых потоков. Тепловые потоки имитировали с помощью мощного
импульсного лазерного излучения (ЛИ), создаваемого ...
Added: September 22, 2026
Iontsev M.A., Mukhin S. I., Fistul M. V., Physical Review B: Condensed Matter and Materials Physics 2016 Vol. 94 No. 17 P. 174–510
We report a theoretical study of the ac response of superconducting quantum metamaterials (SQMs), i.e., an array of qubits (two-level systems) embedded in a low-dissipative resonator. By making use of a particular example of a SQM, namely the array of charge qubits capacitively coupled to the resonator, we obtain a second-order phase transition between an ...
Added: September 22, 2026
Shilov A. L., Elesin L., Kravtsov M. et al., Nature Communications 2026 Vol. 17 No. 1 Article 9734
Identifying the microscopic processes limiting conductivity is essential for understanding correlated quantum materials. In twisted bilayer graphene, metallic resistivity follows ρ ~ Tα with widely varying α, fueling competing interpretations from phonon-limited transport and umklapp scattering to strange metallicity and heavy-fermion renormalization. Here, we use terahertz excitation to selectively heat electrons while keeping the lattice cold, separating ...
Added: September 20, 2026
Ibrahim A., Derkach D., Kaledin M. et al., Computer Physics Communications 2026 Vol. 329 Article 110407
We present RLABC (Reinforcement Learning for Accelerator Beamline Control), an open-source Python framework that automatically transforms standard Elegant beamline configurations into reinforcement learning environments. RLABC integrates with the widely-used Elegant beam dynamics simulation code via SDDS-based interfaces, enabling researchers to apply modern RL algorithms to beamline optimization with minimal RL-specific development. Validation on a test ...
Added: September 20, 2026
Filyaev A. A., Losev A. V., Zavodilenko V. V. et al., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2023 Vol. 16 No. 3.1 P. 237–241
In this paper an important parameter of single-photon detectors, such as quantum efficiency, is considered. Errors in determining this parameter lead to significant errors in the parameters of a quantum key distribution system, where such detectors find their application. Three models are proposed to estimate photon detection efficiency or quantum efficiency and their main advantages ...
Added: May 6, 2026
Makarov V., Abrikosov A., Chaiwongkhot P. et al., Physical Review Applied 2024 Vol. 22 No. 4 P. 044076-1–044076-34
A commercial quantum key distribution (QKD) system needs to be formally certified to enable its wide deployment. The certification should include the system’s robustness against known implementation loopholes and attacks that exploit them. Here we ready a fiber-optic QKD system for this procedure. The system has a prepare-and-measure scheme with decoy-state BB84 protocol, polarization encoding, ...
Added: December 8, 2024
Лескина Э. И., Юрист 2022 № 11 С. 2–6
The development of end-to-end technologies is a priority for many states. The Russian Federation is no exception. The amount of data is growing exponentially every day, and one of the priority tasks is to ensure proper data protection, to ensure information security in general. Quantum technologies are able to provide such security, as well as ...
Added: October 2, 2024
Лескина Э. И., Юрист 2023 № 3 С. 2–7
The subject of this article is the dynamics of the legal regulation of data in the conditions of the formation and development of the metauniverse. The object of the article is the social relations that develop in the process of data circulation in the era of the metaverse. As a result of the study, the ...
Added: October 2, 2024
Ruzhitskaya D., Zhluktova I., Ponosova A. et al., Conference on Lasers and Electro-Optics/Europe (CLEO/Europe 2023) and European Quantum Electronics Conference 2023 Article eb_p_14
Quantum key distribution (QKD) systems provide quantum-safe key exchange. Therefore, complete security analysis of implementations of QKD protocols is in the focus of interest of a worldwide information-security community. For today, a number of QKD loopholes are closed by countermeasures, which are also considered in emerging QKD security evaluation and certification [1–3]. However, new threats ...
Added: September 13, 2024
Nefedov S., Ozhegov R., Evsyutin O. et al., Наноиндустрия 2024 Т. 17 № S10-2 (128) С. 553–558
The paper considers challenges of creating a quantum key distribution system for long-distance trunk line. Besides, it presents the results of design, prototyping and examination of equipment implementing the quantum key distribution protocol with phase-time coding. ...
Added: August 2, 2024
Дуплинский А. В., Хмелев А. В., Мерзлинкин В. Е. et al., Вестник Томского государственного университета. Управление, вычислительная техника и информатика 2023 № 63 С. 103–110
Quantum key distribution is a technology that allows you to generate an encryption key with a high level of secrecy for the secure exchange of information between users. In the last decade, the concept of quantum secure communications has become increasingly widespread around the world. This article outlines the idea of a quantum key distribution ...
Added: April 25, 2024
Losev A., Zavodilenko V. V., Koziy A. et al., IEEE Journal of Quantum Electronics 2022 Vol. 58 No. 3 P. 1–11
We have performed a detailed study of the dependence of afterpulse probability in InGaAs/InP sine-gated SPAD on the dead time and the existing approach for its implementation. We demonstrated an electrical scheme combining sinusoidal gating and active reset. We have shown when such solutions are beneficial from the key distribution point of view, and enough ...
Added: May 12, 2023
Khmelev A., Ivchenko E., Miller A. et al., Entropy 2023 Vol. 25 No. 4 P. 670
Satellite-based link analysis is valuable for efficient and secure quantum communication, despite seasonal limits and restrictions on transmission times. A semi-empirical quantum key distribution model for satellite-based systems was proposed that simplifies simulations of communication links. Unlike other theoretical models, our approach was based on the experimentally-determined atmospheric extinction coefficient typical for mid-latitude ground stations. ...
Added: May 11, 2023
Merzlinkin V., Khmelev A., Duplinsky AV et al., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2022 Vol. 15 No. 3.3 P. 202–206
Quantum communication is a transmission technology that allows legitimate users to share a secret key. The BB84 protocol employs four linear polarization states for encoding in our quantum key distribution system. However, the optical elements affect the polarization features of quantum state, which leads to errors in decoded key. To reduce mistakes and increase device ...
Added: May 11, 2023
Marychev P., Водолазов Д. Ю., Journal of Physics: Condensed Matter 2021 Vol. 33 No. 38 P. 385301
We have calculated kinetic inductance Lk of a thin superconductor/ferromagnet/normal metal strip in an in-plane Fulde–Ferrell (FF) state. We consider range of parameters when FF state appears at temperature TFF < Tc (Tc is a transition temperature to superconducting state) when the paramagnetic response of FN layers overcomes the diamagnetic response of S layer. We ...
Added: January 12, 2023