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Security of entanglement-based QKD with realistic parametric down-conversion sources
Laser Physics Letters. 2023. Vol. 20. No. 8. Article 085203.
K S Kravtsov
The paper analyzes security aspects of practical entanglement-based quantum key distribution
(QKD), namely, BBM92 or entanglement-based BB84 protocol. Similar to prepare-and-measure
QKD protocols, practical implementations of the entanglement-based QKD have to rely upon nonideal
photon sources. A typical solution for entanglement generation is the spontaneous parametric
down-conversion. However, this process creates not only single photon pairs, but also quantum
states with more than two photons, which potentially may lead to security deterioration. We show
that this effect does not impair the security of entanglement-based QKD systems. We also review
the available security proofs and show that properties of the entanglement source have nothing to
do with security degradation.
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
Копьев А., JETP Letters 2026 Vol. 123 No. 5 P. 310–316
The incompressible three-dimensional Euler equations develop very thin pancake-like regions of exponen tially increasing vorticity. The characteristic thickness of such regions decreases exponentially with time, while the other two dimensions do not change considerably, making the flow near each pancake strongly anisotropic. The pancakes emerge in increasing number with time, which may enhance the anisotropy ...
Added: September 18, 2026
Ponosova A., Zhluktova I., Ruzhitskaya D. et al., Applied Physics Letters 2025 Vol. 127 No. 19 P. 194002
Quantum key distribution systems offer cryptographic security, provided that all their components are thoroughly characterized. However, certain components might be vulnerable to laser-damage attacks, particularly when subjected to untested laser parameters. Here, we show that exposing 1550-nm fiber-optic isolators to 1061-nm sub-nanosecond pulsed illumination with 1.16 W average power permanently degrades their isolation performance at ...
Added: December 5, 2025
Lankin A. V., Norman G., Russian Journal of Physical Chemistry A 2025 Vol. 99 No. 11 P. 2833–2904
We present the current state of quantum mechanics, the prospects for its development, and the
strengthening of its influence on scientific and technological progress. We look at quantum mechanics from
four perspectives. The first perspective astonished physicists already with the advent of quantum mechanics—
it is (1) a new way of looking at the world. Over the course ...
Added: November 20, 2025
V. I. Morozov, O. O. Evsyutin, S. I. Nefedov, Problems of Information Transmission 2025 Vol. 61 No. 1 P. 8–26
One of the main applications of quantum communication is quantum key distribution, which solves the problem of secure distribution of cryptographic keys between remote users. This paper investigates the performance of a phase-time coding quantum key distribution protocol belonging to the BB84 protocol family. We construct a simulation model that takes into account the peculiarities ...
Added: April 22, 2025
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
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
Khmelev A., Duplinsky A, Bakhshaliev R et al., Optics Express 2024 Vol. 32 No. 7 P. 11964–11978
The Micius satellite is the pioneering initiative to demonstrate quantum teleportation, entanglement distribution, quantum key distribution (QKD), and quantum-secured communications experiments at the global scale. In this work, we report on the results of the 600-mm-aperture ground station design which has enabled the establishment of a quantum-secured link between the Zvenigorod and Nanshan ground stations ...
Added: April 25, 2024
Miller A., Pismenuk L., Duplinsky AV et al., EPJ QUANTUM TECHNOLOGY 2023 Vol. 10 No. 1 Article 52
A satellite-constellation based global quantum network could allow secure quantum communication between remote users worldwide. Such a constellation could be formed of micro- or even nanosatellites, which have the advantage of being more cost-effective than larger expensive spacecrafts. At the same time, the features of quantum communication impose a number of technical requirements that are ...
Added: April 25, 2024
S P Kulik, K S Kravtsov, S N Molotkov, Laser Physics Letters 2022 Vol. 19 No. 2 Article 025203
The analysis of the security of quantum key distribution systems with respect to an attack with nondemolishing measurement of the number of photons (photon number splitting—PNS attack) is carried out under the assumption that in the communication channel in each parcel there is a pure Fock state with a different number of photons, and the ...
Added: March 12, 2024
Vinetskaya P. M., Kravtsov K. S., Borshchevskaia N. A. et al., Laser Physics Letters 2023 Vol. 20 No. 5 Article 055201
Entangled quantum key distribution (QKD) is a promising way to generate pairs of unconditionally secret keys. In this paper we review possible realizations of entanglement-based QKD and assess their feasibility in terms of implementation complexity and provided security. We also propose a novel active basis choice approach that enables to use only one single-photon detector ...
Added: March 12, 2024
Смирнов И. А., Короченцев Д. А., Черкесова Л. В. et al., Научное обозрение 2020 Т. 3 С. 30–35
Authors consider vulnerabilities of quantum cryptography and quantum key distribution systems. Despite
of reliability on quantum communication line as such, direction of successful hacker’s attack is transmitting data
software, or vulnerabilities in hardware–and–software implementation of quantum key distribution systems. For
domestic quantum technologies application, it is possible to use Russian certified encryption systems («Kuznechik»,
GOST 34.12–2015, or «Magma», GOST ...
Added: May 10, 2023