Noise-Immunity Kazan Quantum Line at 143 Km Regular Fiber Link

arXiv:1910.10011v1 [quant-ph] 22 Oct 2019 itneQshv enrcnl bandwt SPAD with obtained detectors. recently SSPD been long- and and have networks QCs quantum urban distance stable Promis- for results supercon- [12–16]. ing (SSPD) high-efficiency detector and single-photon 11] avalancheducting single-photon [10, (SPAD) used: quan- detector widely of communica- are types quantum detectors main two tum high performance, func- ensure devices main (QC) opera- to tion its during Currently, as maintenance well of tion. as complexity system, and the cost tionality ratio, of noise reliability to signal and utilization, determines signal largely quantum which the detector, photon the critical is expensive element the quan- [4–9], most schemes In communication temperature. tum room at operating module of detection capable single-photon and modulator beamsplit- phase polarization the ter, a quantum 3], were (bps). which [2, a second of protocol components per BB84 with main phase-coded bits nm a 60 used 1550 about system of of This (SKR) wavelength rate a distance key at secret a km over 67 demonstrated [1]. was of work the distribution in key of implemented The cities was Swiss Lausanne the and between Geneva line channel communication fiber-optic urban standard in a using (QKD) distribution euiyaayi a enpromdfrti ytmby system this for performed been The has conditions. analysis weather security enabling diverse during stabilised, is distribution automatically system key QKD and of robust prototype The compact, net- of Tokyo. fiber link central km in telecommunication work 45 metropolitan standard installed a that over kbps. an period deployed 300 total day around was a of 34 system rate a providing The key over sustained system data a key QKD to secure corresponded rate of Gbit bit 878 high proto- of a the of presented type using group Mach-Zehnder by UK-Japan with [17], a 19] interferometers, [18, of In protocol composed BB84 photodiode. detector phase-coding avalanche SPAD Peltier a contained cooled [1], described work system, in communication quantum commercial Cwt SPAD. with QC key quantum of system commercial first the of One lgI Bannik I. Oleg NECT UNU NETWORKS QUANTUM INTERCITY aksM Arslanov M. Narkis nteln f3 eiesfradsac f13k uig1. h 16.5 during km 143 of distance long- a demonstrated for the ra decibels of generation 37 perspectives key commercialization of secret line Average the wave. in subcarrier Re noise-immunity in the high in coding providing Apastovo of prototype village distribution urban-type key the and Kazan of city os-muiyKznqatmln t13k eua brlin fiber regular km 143 at line quantum Kazan Noise-immunity eeprmnal eosrt ogdsac unu com quantum long-distance a demonstrate experimentally We 1 h elkondmntaino a of demonstration well-known The , 2 ea .Gilyazov R. Lenar , 2 1 aa unu omncto t,1 .Mr,Kzn401,R 420111, Kazan Marx, K. 10 Ltd, Communication Quantum Kazan aa unu etr aa ainlRsac ehia Un Technical Research National Kazan Center, Quantum Kazan ..ANTplvKI 0K ax aa 211 usaand Russia 420111, Kazan Marx, K. 10 A.N.Tupolev-KAI, n.a. 1 , 2 lkad .Litvinov A. Aleksandr , 1 , 2 ru .Gleim V. Artur , 1 , 2 letR Yafarov R. Albert , oswt o akcutrt.Sal maintenance-free pho- Stable detect rate. 30 count to with dark employed low link were a with detectors optical tons SSPD loop-back were km receiver loss. 90 photon dB a the and metropolitan to Tokyo transmitter connected photon the A in installed area. 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Classical Sync. operation was achieved for 25 days, where the average se- ALICE Channel BOB ± EF cure key generation rate 1.1 0.5 kbps and the quantum DL 2 D bit error rate 2.6%. The experiments have shown a sig- (Sync.) (Sync.) VCO Amplifier PLL FPGA PLL nificant impact of meteorological conditions on the main VCO CC EPM B FPGA parameters of QKD system. CC EPM To move from existing commercial QKD-systems oper- AMD A 143km ating at distances of about 100 km to new solutions stable Circulator F CDC Quantum B A PC OI OAM DL 1 OPM OA Channel OPM at ultra-long distances about of 150-200 km, it is desir- (Signal) SSPD able to use optical schemes that do not include interferometers. In this work we realized stable interferometer- free one-way QKD system at 143 km regular fiber line by Figure 1. One-way scheme for the long-distance QC complex. DL1 and DL2: diode laser 1 and 2; OI: optical isolator; OAM: using subcarrier waves phase-coding protocol and discuss optical amplitude modulator; OPM: optical phase modulator; prospective of this system for ultra-long distance QC. OA: optical attenuator; FPGA: field-programmable gated- array and these serve (in conjunction with the control com- NOISE IMMUNITY PROTOTYPE FOR puters) as the control apparatus of this system; VCO: volt- ULTRA-LONG DISTANCE QC age control oscillator; PLL: phase looked loop; EPM: electrical phase modulator; AMD: amplitude modulator driver; Noise immunity problem. Noise immunity and ac- CDC: chromatic dispersion compensator; PC: polarization controller; F: optical filter; SSPD: superconducting single- tive intelligent stabilization [30–32] are very impor- photon detector; EF: electrical filter; D: photodiode; Φ: opti- tant characteristics of systems for ultra-long distance cal phase modulator; CC: classical computer. QCs. The characteristics allow to classify the existing long-distance QCs [33, 34] by using extensive quantum sidebands. The relative phase of the subcarrier waves is analysis [35] (traditional for cryptography) and intelli- determined by the phase of the modulating electromag- gent noise-analysis [36–39] (traditional for steganogra- netic field with modulation index of 0.033. Further, the phy, friend identification systems and general type com- optical signal was attenuated by the variable attenua- plex systems). For solution of the problems of noise im- tor to the sidebands power level defined by the protocol, munity in relation to the influences on both the fiber namely, no more than 0.2 photons per modulation cy- communication line and QKD apparatus in the network cle. Chromatic dispersion compensator was introduced nodes, we must accordingly abandon the use of interfer- to eliminate the detrimental influence of chromatic dis- ometers [40] reducing vibration resistance of nodes and persion effect on the interferometric visibility on the re- polarization coding sensitive to deformations, vibration ceiver unit side. Alice overall output power was 79.3 pW. and temperature changes in the fiber. Both Alice’s and Bob’s phase modulators contained an Phase-coding as a solution. The unique noise immu- linear polarizer aligned with the electro-optical crystal nity is inherent to the subcarrier wave phase-coding pro- axis to ensure fully modulated signal. tocol [41] what distinguishes this approach from many To maximize signal utilization, Bob used a polarization others [42–44]. A quantum signal is not directly gener- controller at its input to compensate for polarization dis- ated by the source in the one-way QKD system of sub- tortions introduced by the fiber optics line. Following carrier frequencies, but is created as a result of phase the maximum counting rate at the output of a single- modulation of carrier wave at Alice and Bob sides [41]. photon detector, the controller automatically aligns the A description of a typical technological implementation signal polarization along the axis of the OPM polarizer. of this protocol can be found in [45]. Below we offer a After the phase modulation, the input light was filtered modified variant of this QKD-system. at narrow band notch filter. Components and properties. We propose a QKD- Our approach uses only one sideband, introducing an system of one-way QC shown in Fig. 1. Tunable wave- additional 3 dB signal loss, while that allows us to filter length continuous wave mode DFB-laser with 5 kHz fre- out both carrier wavelength and fiber line background quency linewidth was used as a carrier wavelength source spurious noise in a cheap simple way using only one spec- for quantum channel. The wavelength was adjusted in tral filter. One of the sidebands is launched to a SSPD- accordance with the filter bandwidth in the receiving detector. SSPD operates at a temperature of 2.1 K and unit (Bob side). The laser radiation was launched to has a low dark count rate of 0.5 Hz with a high quantum the electro-optical amplitude modulator for generation of efficiency of 50 %. short phase modulator was a sequence of 2.5 ns pulses at the repetition rate of 100 MHz. Then the generated pulse were transmitted to the optical phase modulator (OPM) EXPERIMENTAL DEMONSTRATION providing uniform phase modulation over the entire pulse duration. 4.8 GHz electromagnetic field was also applied For the field tests, we used Kazan-Apastovo regular to the radio-frequency input of OPM to generate optical fiber link with a length of 143 km and losses of 37 dB 3 in the quantum channel and 45 dB in the synchroniza-

secret key rate, bps ranged data tion channel with erbium-doped ﬁber ampliﬁer. The to-

(a)

tal time for continuous testing was 16.5 hours. About 18 700 kbit of key information was generated in the quantum channel with an average value of the secret quantum

key generation rate of 12 bps. The value of QBER was 15 in the stable range from 0.5 % to 3.5 %, on average, the value of QBER ∼ 2 % (see Fig. 2). This generation rate allows to change the 256-bit encryption key up to two 12 times per minute. The data of the stable experimental demonstration show the possible using of the proposed

QKD system in commercial long-range QCs. 9 In our work, the results were obtained in a long- distance and regular trunk telecommunication ﬁber be-

6 tween the cities of the Russian Federation. Basic char- [10,90]-percentile trend channel at 50 points acteristics of the tests of our QKD system for urban

QBER, % ranged data quantum networks [46, 47] and intercity trunk lines [48] 4 are presented in Tab. I. For comparison, Tab. I also (b) presents the basic characteristics of the well-known long-

range QKD systems discussed in the introduction which 3 were also tested under real conditions [49].

Kazan quantum lines Length SKR Detector Loss (dB); Group 2 (km) (bps) QBER (%) 4 12 2 · 10 ∗SPAD 7; 4 Russia † 143 12 SSPD 37; 2 Russia 1 International commercial systems 67 60 [1] SPAD 14; 6 Switzerland 5 0 100 200 300 400 500 45 3 · 10 [17] SPAD 14; 4 Japan 5 measurement number 66 5 · 10 [22] SPAD 21; 5 China 97 800 [25] SSPD 33; 3 Japan Figure 2. Distributions for (a) secret key rate (∼ 12 bps) and 90 1 · 103 [28] SSPD 30; 3 Japan (b) QBER (∼ 2%) for two-day measurements. Name Kazan-Q1 Detector SSPD Table I. Basic characteristics of the proposed QKD system: ∗Kazan city quantum network (previous ﬁeld tests, Kazan, or SPAD May 2017 [46, 47]), †intercity long-distance QC (current ex- Coding Phase in Active Phase periment, Kazan-Apastovo, August 2019 [48]). subcarrier wave element modulator Security Quantum and QRNG On PD with It is worth noting that in [50, 51] and [52, 53] tests of var- classical robust-defense ious QKD systems at shorter distances and using ultra- Noise Network nodes Decoys and Amplitude low loss ﬁbers are presented. immunity and lines diagnostics modulator and AI

Table II. Outlook for the complex ”Kazan-Q1”. Here: QRNG: INNOVATION OUTLOOK quantum random number generator; PD: PIN-photodiode; AI: artiﬁcial intelligence. Based on the demonstrated QKD prototype, we propose the concept of a universal QC complex ”Kazan-Q1” ”Kazan-Q1” in the context of world achievements in the (see outlook Tab. II and patents [54–58]) which combines area of innovative quantum technologies: the technological simple solutions, noise immunity of the 1) statistical monitoring with AI for keys and electronic subcarrier wave coding and robust quantum-classical in- components based on the robust nonparametric criteria formation protection based on the extended statistical [37, 60–63]; data mining against new types of quantum attacks [59]. 2) compact [64–66] planar implementation [67] without We see the following distinctive features and prospects using interferometers for the main components [9]: beam for the development of the long-distance QC complex splitter [68–70], planar phase modulator [71], high purity 4

QRNG on PD [72] with robust-defense [61, 73–76]; 3) implementation of advanced decoy states [77, 78] in Konstantin Sergeevich Melnik, a complex using intelligent monitoring methods [37, 61] (b. 1993), in 2018 graduated from Institute of Radio for quantum diagnostics of network integrity and intru- Electronics and Telecommunications of Kazan National sion detection [79–81]; Research Technical University in the direction of "Radio 4) advanced post-processing [82] for error correction Engineering", PhD student at the Kazan Quantum and modeling in optical simulator for testing and spe- Center of the KNRTU-KAI. cialization of software for specific urban conditions. Area of interest: quantum communications, optoelec- Acknowledgments. Research is financially supported tronics, photonics. by a grant of the Government of the Russian Federation, E-mail: [email protected] project No. 14.Z50.31.0040, February 17, 2017. We are very grateful to the companies of PJSC Narkis Musavirovich Arslanov, ”Tattelecom” and PJSC ”Rostelecom” for providing (b. 1980), in 2003 graduated from the the Physics De- working fiber-optic communication lines and for officially partment of Kazan Federal University, senior researcher documenting Russia’s record [48] for the range of long- at the Kazan Quantum Center of the KNRTU-KAI. distance QC during this experimental demonstration. Area of interest: quantum communications, photonics. E-mail: [email protected]

INFORMATION ABOUT AUTHORS Aleksandr Alekseevich Litvinov, (b. 1985), in 2008 graduated the department of Theory Oleg Igorevich Bannik, of Relativity and Gravity of the Physics Department of (b. 1988), in 2012 graduated from the faculty of elec- Kazan Federal University in the direction of “Physics”, tronics of Saint Petersburg Electrotechnical University engineer at the Kazan Quantum Center of the KNRTU- in the direction of "Electronics and Microelectron- KAI. ics", researcher at the Kazan Quantum Center of the Area of interest: quantum communications, optoelec- KNRTU-KAI. tronics, robust methods, quantum memory, software, Area of interest: quantum communications, optoelec- economics. tronics, photonics. E-mail: [email protected] E-mail: [email protected] Albert Ruslanovich Yafarov, Lenar Rishatovich Gilyazov, (b. 1977), in 2006 graduated from the Department of (b. 1985), in 2008 graduated from the the Physics Geography of Kazan State University in 2006 with a Department of Kazan Federal University, researcher at degree in Geography, engineer at the Kazan Quantum the Kazan Quantum Center of the KNRTU-KAI. Center of the KNRTU-KAI. Area of interest: quantum communications, optoelec- Area of interest: quantum communications, robust tronics, photonics. methods, quantum memory, project management, public E-mail: [email protected] relations, economics. E-mail: [email protected] Artur Viktorovich Gleim, (b. 1990), in 2012 graduated from ITMO University Sergey Andreevich Moiseev, in the direction of "Photonics and Optoinformatics", (b. 1957), in 1979 graduated with honors from the phys- candidate of technical sciences, head of lab. at the ical faculty of Kazan State University in the direction Kazan Quantum Center of the KNRTU-KAI. of "Radiophysics". Doctor of Phys.-Math. Sciences, Area of interest: quantum communications, optoelec- prof. Department of Radio-photonics and Microwave tronics, photonics. Technologies, KNRTU-KAI, Director of the Kazan E-mail: [email protected] Quantum Center KNRTU-KAI. Area of interest: optics and spectroscopy, quantum Nikolay Sergeevich Perminov, memory, quantum informatics, quantum communica- (b. 1985), in 2008 graduated the department of Theory tions, nonlinear and coherent optics. of Relativity and Gravity of the Physics Department of E-mail: [email protected] Kazan Federal University in the direction of “Physics”, researcher at the Kazan Quantum Center of the KNRTU-KAI. ∗ [email protected] Area of interest: optimal control, quantum informatics, [1] D. Stucki, N. Gisin, O. Guinnard, G. Ribordy, and statistics, software, economics. H. Zbinden, “Quantum key distribution over 67 km with E-mail: [email protected] a plug&play system,” New Journal of Physics, vol. 4, 5

no. 1, p. 41, 2002. recovery time of snspds and its application for quantum [2] C. Bennett and G. Brassard, “Quantum cryptography: communication,” in Quantum Information and Measure- Public key distribution and coin tossing,” in Theoretical ment, pp. S1D–3, Optical Society of America, 2019. Computer Science, vol. 560, pp. 175–179, 01 1984. [17] A. Dixon, J. Dynes, M. Lucamarini, B. Fröhlich, [3] A. Muller, T. Herzog, B. Huttner, W. Tittel, H. Zbinden, A. Sharpe, A. Plews, S. Tam, Z. Yuan, Y. Tanizawa, and N. Gisin, “Plug and play systems for quantum H. Sato, S. Kawamura, M. Fujiwara, M. Sasaki, and cryptography,” Applied Physics Letters, vol. 70, no. 7, A. Shields, “High speed prototype quantum key distri- pp. 793–795, 1997. bution system and long term field trial,” Optics express, [4] N. Gisin, G. Ribordy, W. Tittel, and H. Zbinden, “Quan- vol. 23, no. 6, pp. 7583–7592, 2015. tum cryptography,” Reviews of modern physics, vol. 74, [18] V. Scarani and R. Renner, “Quantum cryptography no. 1, p. 145, 2002. with finite resources: Unconditional security bound for [5] U. L. Andersen, J. S. Neergaard-Nielsen, P. Van Loock, discrete-variable protocols with one-way postprocessing,” and A. Furusawa, “Hybrid discrete-and continuous- Physical review letters, vol. 100, no. 20, p. 200501, 2008. variable quantum information,” Nature Physics, vol. 11, [19] H.-K. Lo, H. F. Chau, and M. Ardehali, “Efficient quan- no. 9, p. 713, 2015. tum key distribution scheme and a proof of its uncon- [6] E. Diamanti, H.-K. Lo, B. Qi, and Z. Yuan, “Practical ditional security,” Journal of Cryptology, vol. 18, no. 2, challenges in quantum key distribution,” npj Quantum pp. 133–165, 2005. Information, vol. 2, p. 16025, 2016. [20] M. Lucamarini, K. Patel, J. Dynes, B. Fröhlich, [7] W. Zhang, D.-S. Ding, Y.-B. Sheng, L. Zhou, B.-S. Shi, A. Sharpe, A. Dixon, Z. Yuan, R. Penty, and A. Shields, and G.-C. Guo, “Quantum secure direct communication “Efficient decoy-state quantum key distribution with with quantum memory,” Physical review letters, vol. 118, quantified security,” Optics express, vol. 21, no. 21, no. 22, p. 220501, 2017. pp. 24550–24565, 2013. [8] F. Yan, A. M. Iliyasu, and P. Q. Le, “Quantum image pro- [21] S.-K. Liao, W.-Q. Cai, W.-Y. Liu, L. Zhang, Y. Li, J.-G. cessing: a review of advances in its security technologies,” Ren, J. Yin, Q. Shen, Y. Cao, Z.-P. Li, F.-Z. Li, X.-W. International Journal of Quantum Information, vol. 15, Chen, L.-H. Sun, J.-J. Jia, J.-C. Wu, X.-J. Jiang, J.-F. no. 03, p. 1730001, 2017. Wang, Y.-M. Huang, Q. Wang, Y.-L. Zhou, L. Deng, [9] A. Ac´ın, I. Bloch, H. Buhrman, T. Calarco, C. Eichler, T. Xi, L. Ma, T. Hu, Q. Zhang, Y.-A. Chen, N.-L. Liu, J. Eisert, D. Esteve, N. Gisin, S. J. Glaser, F. Jelezko, X.-B. Wang, Z.-C. Zhu, C.-Y. Lu, R. Shu, C.-Z. Peng, J.- S. Kuhr, M. Lewenstein, M. F. Riedel, P. O. Schmidt, Y. Wang, and J.-W. Pan, “Satellite-to-ground quantum R. Thew, A. Wallraff, I. Walmsley, and F. K. Wilhelm, key distribution,” Nature, vol. 549, no. 7670, p. 43, 2017. “The quantum technologies roadmap: a european com- [22] Y. Mao, B.-X. Wang, C. Zhao, G. Wang, R. Wang, munity view,” New Journal of Physics, vol. 20, no. 8, H. Wang, F. Zhou, J. Nie, Q. Chen, Y. Zhao, Q. Zhang, p. 080201, 2018. J. Zhang, T.-Y. Chen, and J.-W. Pan, “Integrating quan- [10] A. Tosi, N. Calandri, M. Sanzaro, and F. Acerbi, “Low- tum key distribution with classical communications in noise, low-jitter, high detection efficiency ingaas/inp backbone fiber network,” Optics express, vol. 26, no. 5, single-photon avalanche diode,” IEEE Journal of selected pp. 6010–6020, 2018. topics in quantum electronics, vol. 20, no. 6, pp. 192–197, [23] T.-Y. Chen, J. Wang, H. Liang, W.-Y. Liu, Y. Liu, 2014. X. Jiang, Y. Wang, X. Wan, W.-Q. Cai, L. Ju, L.-K. [11] J. Zhang, M. A. Itzler, H. Zbinden, and J.-W. Pan, Chen, L.-J. Wang, Y. Gao, K. Chen, C.-Z. Peng, Z.-B. “Advances in ingaas/inp single-photon detector systems Chen, and J.-W. Pan, “Metropolitan all-pass and inter- for quantum communication,” Light: Science & Applica- city quantum communication network,” Optics express, tions, vol. 4, no. 5, p. e286, 2015. vol. 18, no. 26, pp. 27217–27225, 2010. [12] C. M. Natarajan, M. G. Tanner, and R. H. Hadfield, “Su- [24] J. Yin, J.-G. Ren, H. Lu, Y. Cao, H.-L. Yong, Y.- perconducting nanowire single-photon detectors: physics P. Wu, C. Liu, S.-K. Liao, F. Zhou, Y. Jiang, X.-D. and applications,” Superconductor science and technol- Cai, P. Xu, G.-S. Pan, J.-J. Jia, Y.-M. Huang, H. Yin, ogy, vol. 25, no. 6, p. 063001, 2012. J.-Y. Wang, Y.-A. Chen, C.-Z. Peng, and J.-W. Pan, [13] W. Zhang, L. You, H. Li, J. Huang, C. Lv, L. Zhang, “Quantum teleportation and entanglement distribution X. Liu, J. Wu, Z. Wang, and X. Xie, “Nbn superconduct- over 100-kilometre free-space channels,” Nature, vol. 488, ing nanowire single photon detector with efficiency over no. 7410, p. 185, 2012. 90% at 1550 nm wavelength operational at compact cry- [25] A. Tanaka, M. Fujiwara, S. W. Nam, Y. Nambu, S. Taka- ocooler temperature,” Science China Physics, Mechanics hashi, W. Maeda, K.-i. Yoshino, S. Miki, B. Baek, & Astronomy, vol. 60, no. 12, p. 120314, 2017. Z. Wang, A. Tajima, M. Sasaki, and A. Tomita, “Ul- [14] P. Zolotov, A. Divochiy, Y. Vakhtomin, M. Moshkova, tra fast quantum key distribution over a 97 km in- P. Morozov, V. Seleznev, and K. Smirnov, “Photon- stalled telecom fiber with wavelength division multiplex- number-resolving SSPDs with system detection efficiency ing clock synchronization,” Optics express, vol. 16, no. 15, over 50% at telecom range,” AIP Conference Proceedings, pp. 11354–11360, 2008. vol. 1936, no. 1, p. 020019, 2018. [26] H.-K. Lo, X. Ma, and K. Chen, “Decoy state quantum [15] K. Roy, T. Ahmed, H. Dubey, T. P. Sai, R. Kashid, key distribution,” Physical review letters, vol. 94, no. 23, S. Maliakal, K. Hsieh, S. Shamim, and A. Ghosh, p. 230504, 2005. “Number-resolved single-photon detection with ultralow [27] W.-Y. Hwang, “Quantum key distribution with high loss: noise van der waals hybrid,” Advanced Materials, vol. 30, toward global secure communication,” Physical Review no. 2, p. 1704412, 2018. Letters, vol. 91, no. 5, p. 057901, 2003. [16] C. Autebert, M. Perrenoud, M. Caloz, G. Gras, E. Amri, [28] K. Shimizu, T. Honjo, M. Fujiwara, T. Ito, K. Tamaki, H. Zbinden, and F. Bussières, “Direct measurement of the S. Miki, T. Yamashita, H. Terai, Z. Wang, and M. Sasaki, 6

“Performance of long-distance quantum key distribution [45] A. Gleim, V. Egorov, Y. V. Nazarov, S. Smirnov, over 90-km optical links installed in a field environment V. Chistyakov, O. Bannik, A. Anisimov, S. Kynev, of tokyo metropolitan area,” Journal of Lightwave Tech- A. Ivanova, R. Collins, S. A. AU Kozlov, and G. S. Buller, nology, vol. 32, no. 1, pp. 141–151, 2013. “Secure polarization-independent subcarrier quantum [29] S. N. Molotkov, “Analog of differential–phase quantum key distribution in optical fiber channel using bb84 pro- cryptography on coherent states with provable crypto- tocol with a strong reference,” Optics express, vol. 24, graphic security,” JETP letters, vol. 102, no. 6, pp. 396– no. 3, pp. 2619–2633, 2016. 403, 2015. [46] O. Bannik, V. Chistyakov, L. Gilyazov, K. Melnik, [30] S. Kulik, S. Molotkov, and T. Potapova, “Method of A. Vasiliev, N. Arslanov, A. Gaidash, A. Kozubov, the balancing of Mach-Zehnder fiber-optic interferome- V. Egorov, S. Kozlov, A. Gleim, and S. Moiseev, “Multin- ters in single-pass quantum cryptography,” JETP letters, ode subcarrier wave quantum communication network,” vol. 98, no. 10, pp. 626–631, 2014. in QCrypt 2017 held at the University of Cambridge on [31] S. P. Kulik and S. N. Molotkov, “On the on-line stabi- 18-22, September 2017 in Cambridge, United Kingdom, lization of visibility of interference in fiber optic quantum p. Th413, Centre for Photonic Systems, University of cryptography,” JETP letters, vol. 99, no. 12, pp. 725–730, Cambridge, 2017. 2014. [47] KQC KNRTU-KAI, ITMO, and PJSC ”Tattelecom”, [32] K. Balygin, A. N. Klimov, S. P. Kulik, and S. N. “The first multi-node quantum network in the Molotkov, “Active stabilization of the optical part in fiber CIS was successfully launched in Kazan,” News- optic quantum cryptography,” JETP Letters, vol. 103, center of KNRTU-KAI, 12 may 2017. In no. 6, pp. 420–424, 2016. Russian news: Первая в СНГ многоузловая [33] S. N. Molotkov, “On the resistance of the quantum key квантовая сеть успешно заработала в Казани. distribution with phase-time encoding for long commu- https://kai.ru/news/new?id=5931227. nication channels,” JETP letters, vol. 88, no. 4, pp. 275– [48] KQC KNRTU-KAI, PJSC ”Rostelecom”, and 280, 2008. PJSC ”Tattelecom”, “In Russia, quantum encryp- [34] S. N. Molotkov, “On a solution to the problem of ensur- tion has been successfully tested on the fiber op- ing the security of quantum cryptography for an infinite tic with a record distance,” Press-center of PJSC communication channel,” JETP letters, vol. 93, no. 12, ”Rostelecom”, 25 september 2019. In Russian p. 747, 2011. news: В России успешно протестировали квантовое [35] S. N. Molotkov, “On the complexity of search for keys шифрование на ВОЛС с рекордным расстоянием. in quantum cryptography,” JETP letters, vol. 103, no. 5, https://www.company.rt.ru/press/news/ pp. 345–349, 2016. d452080/?backurl=/press/#_ftnref1. [36] R. R. Nigmatullin, G. Maione, P. Lino, F. Saponaro, and [49] “Notes on academic discussions and some recent ideas on W. Zhang, “The general theory of the quasi-reproducible certification ranks.” Early, in [83] attempt was reported experiments: How to describe the measured data of com- to realize a stable long-distance QC at regular fiber line, plex systems?,” Communications in Nonlinear Science where for the conditions analogous to the our conditions and Numerical Simulation, vol. 42, pp. 324–341, 2017. (37dB losses), the value SKR/clock-rate≈7 bps/100MHz [37] R. R. Nigmatullin and A. S. Vorobev, “The “universal” was obtained, which is about 2 times lower than the val- set of quantitative parameters for reading of the trendless ues 12 bps/100MHz of our experimental results (see Tab. sequences,” Fluctuation and Noise Letters, p. 1950023, I). However, in this work [83], it was impossible to ob- 2019. tain a sufficiently stable operation of the QKD system for [38] R. Nigmatullin, A. Vorobev, H. Budnikov, A. Sidelnikov, several days to be sure of required security parameters. and E. Maksyutova, “Detection of additives with the We assume that after resolving stabilization issues (as help of discrete geometrical invariants,” Applied Sciences, was done, for example, in a series of works [30–32]), the vol. 9, no. 5, p. 926, 2019. QKD system [83, 84] could be able to operate in regular [39] R. R. Nigmatullin and J. A. T. Machado, “Forecasting long-distances lines. New scientific ideas [85] about ultra- of random sequences and prony decomposition of finance high quantum security, which so far operate in essence data,” Analysis, vol. 36, no. 2, pp. 75–88, 2016. only with one single concept of informational entropy [40] S. N. Molotkov, “Multiplex quantum cryptography based [86], are proved in the framework of standard statisti- on time coding without interferometers,” Journal of Ex- cal methods. However, it is well known that the quan- perimental and Theoretical Physics Letters, vol. 79, no. 9, titative proof of the randomness of the number genera- pp. 445–449, 2004. tor, which is the most significant primitive of any true [41] J.-M. Merolla, Y. Mazurenko, J.-P. Goedgebuer, and quantum crypto-system, uses at least 20-30 different sta- W. T. Rhodes, “Single-photon interference in sidebands tistical tests (NIST, U1) [75, 87, 88]. In simple terms, of phase-modulated light for quantum cryptography,” the significance level of the most traditional evidence of < Physical review letters, vol. 82, no. 8, p. 1656, 1999. quantum security is about 1/20-1/30 (∼ 5%) with re- [42] S. Wehner, D. Elkouss, and R. Hanson, “Quantum in- spect to the advanced statistical methods (such as data ternet: A vision for the road ahead,” Science, vol. 362, mining, including NIST-algorithms, and artificial intelli- no. 6412, p. eaam9288, 2018. gence) that are now applied in all high-tech areas. There- [43] I. B. Djordjevic, “Recent quantum-key distribution fore, the development of classification and certification schemes,” in Physical-Layer Security and Quantum Key ranks must go only together with modern methods of Distribution, pp. 391–416, Springer, 2019. artificial intelligence (AI). We are currently developing [44] M. Razavi, A. Leverrier, X. Ma, B. Qi, and Z. Yuan, and patenting methods for robust classification of com- “Quantum key distribution and beyond: introduction,” plex noise-like data for the basic primitives of quantum JOSA B, vol. 36, no. 3, pp. QKD1–QKD2, 2019. crypto-complexes [37, 54–58, 61–63, 89, 90]. 7

[50] D. Bacco, I. Vagniluca, B. Da Lio, N. Biagi, A. Della Fr- tions of a quantum channel,” patent application of era, D. Calonico, C. Toninelli, F. S. Cataliotti, M. Bellini, the Russian Federation, no. 2019117287, 2019. In L. K. Oxenløwe, and A. Zavatta, “Field trial of a finite- Russian: Банник О.И., Гилязов Л.Р., Литвинов key quantum key distribution system in the florence А.А., Арсланов Н.М., Мельник К.С., Моисеев С.А., metropolitan area,” arXiv preprint arXiv:1903.12501, Перминов Н.С., Яфаров А.Р., Гильмутдинов А.Х., 2019. Устройство для передачи квантовых состояний с [51] I. Choi, Y. R. Zhou, J. F. Dynes, Z. Yuan, A. Klar, компенсацией хроматических искажений квантового A. Sharpe, A. Plews, M. Lucamarini, C. Radig, J. Neu- канал, заявка на патент 2019117287. bert, H. Griesser, M. Eiselt, C. Chunnilall, G. Lepert, [58] N. Perminov, R. Nigmatullin, O. Bannik, L. Gilyazov, A. Sinclair, J.-P. Elbers, A. Lord, and A. Shields, “Field K. Melnik, A. Litvinov, and A. Yafarov, “Method for trial of a quantum secured 10 gb/s dwdm transmis- defense random number generator,” patent application sion system over a single installed fiber,” Optics express, of the Russian Federation, no. 2019129707, 2019. In vol. 22, no. 19, pp. 23121–23128, 2014. Russian: Перминов Н.С., Нигматуллин Р Р., Банник [52] N. Walenta, D. Caselunghe, S. Chuard, M. Domer- О.И., Гилязов Л.Р., Мельник К.С., Литвинов А.А., gue, M. Hagerman, R. Hart, D. Hayford, R. Houl- Яфаров А.Р., Способ защиты генератора случайных mann, M. Legré, T. McCandlish, L. Monat, A. Morrow, чисел, заявка на патент 2019129707. G. Ribordy, D. Stucki, M. Tourville, P. Trinkler, and [59] A. Y. Bykovsky and I. Kompanets, “Quantum cryptog- R. Wolterman, “Towards a north american qkd backbone raphy and combined schemes of quantum cryptography with certifiable security,” in Proc. Qcrypt, 2015. communication networks,” Quantum Electronics, vol. 48, [53] A. Boaron, G. Boso, D. Rusca, C. Vulliez, C. Autebert, no. 9, p. 777, 2018. M. Caloz, M. Perrenoud, G. Gras, F. Bussières, M.-J. Li, [60] R. R. Nigmatullin, “New noninvasive methods for ‘read- D. Nolan, A. Martin, and H. Zbinden, “Secure quantum ing’of random sequences and their applications in nan- key distribution over 421 km of optical fiber,” Physical otechnology,” in New trends in nanotechnology and frac- review letters, vol. 121, no. 19, p. 190502, 2018. tional calculus applications, pp. 43–56, Springer, 2010. [54] O. Bannik, L. Gilyazov, A. Litvinov, N. Arslanov, [61] N. Perminov, O. Bannik, D. Y. Tarankova, and R. Nig- K. Melnik, S. Moiseev, A. Gleim, S. Kynev, and matullin, “RCF-defense for quantum randomness,” arXiv V. Chistyakov, “Device for transmitting quantum states preprint arXiv:1810.04295, 2018. with automatic calibration of the basis states of the [62] M. A. Smirnov, N. S. Perminov, R. R. Nigmatullin, A. A. receiver,” patent application of the Russian Federa- Talipov, and S. A. Moiseev, “Sequences of the ranged tion, no. 2019111179, 2019. In Russian: Банник amplitudes as a universal method for fast noninvasive О.И., Гилязов Л.Р., Литвинов А.А., Арсланов Н.М., characterization of SPAD dark counts,” Applied optics, Мельник К.С., Моисеев С.А., Глейм А.В., Кынев vol. 57, no. 1, pp. 57–61, 2018. С.М., Чистяков В.В., Устройство для передачи [63] N. S. Perminov, M. A. Smirnov, R. R. Nigmatullin, квантовых состояний с автоматической калибровкой A. A. Talipov, and S. A. Moiseev, “SRA vs his- базисных состояний приемника, заявка на патент tograms in the noise analysis of SPAD,” arXiv preprint 2019111179. arXiv:1712.02612, 2017. [55] O. Bannik, L. Gilyazov, A. Litvinov, N. Arslanov, [64] K. Mel’nik, N. Arslanov, O. Bannik, L. Gilyazov, K. Melnik, S. Moiseev, A. Gleim, S. Kynev, and V. Egorov, A. Gleim, and S. Moiseev, “Using a het- V. Chistyakov, “Device for transmitting quantum erodyne detection scheme in a subcarrier wave quan- states with filtering the background illumination of tum communication system,” Bulletin of the Russian a quantum channel,” patent application of the Rus- Academy of Sciences: Physics, vol. 82, no. 8, pp. 1038– sian Federation, no. 2019117522, 2019. In Rus- 1041, 2018. sian: Банник О.И., Гилязов Л.Р., Литвинов А.А., [65] G. Zhang, J. Haw, H. Cai, F. Xu, S. Assad, J. Fitzsimons, Арсланов Н.М., Мельник К.С., Моисеев С.А., Глейм X. Zhou, Y. Zhang, S. Yu, J. Wu, W. Ser, L. C. Kwek, А.В., Кынев С.М., Чистяков В.В., Устройство and A. Q. Liu, “An integrated silicon photonic chip plat- для передачи квантовых состояний с фильтрацией form for continuous-variable quantum key distribution,” фоновой засветки квантового канала, заявка на Nature Photonics, pp. 1–4, 2019. патент 2019117522. [66] T. A. Eriksson, T. Hirano, B. J. Puttnam, [56] O. Bannik, L. Gilyazov, A. Litvinov, N. Arslanov, G. Rademacher, R. S. Lu´ıs, M. Fujiwara, R. Namiki, K. Melnik, S. Moiseev, N. Perminov, A. Yafarov, and Y. Awaji, M. Takeoka, N. Wada, and M. Sasaki, A. H. Gilmutdinov, “Device for transmitting quantum “Wavelength division multiplexing of continuous variable states with compensation for polarization distortions quantum key distribution and 18.3 tbit/s data channels,” of a quantum channel,” patent application of the Rus- Communications Physics, vol. 2, no. 1, p. 9, 2019. sian Federation, no. 2019117383, 2019. In Russian: [67] A. Orieux and E. Diamanti, “Recent advances on in- Банник О.И., Гилязов Л.Р., Литвинов А.А., Арсланов tegrated quantum communications,” Journal of Optics, Н.М., Мельник К.С., Моисеев С.А., Перминов vol. 18, no. 8, p. 083002, 2016. Н.С., Яфаров А.Р., Гильмутдинов А.Х., Устройство [68] B. Desiatov, A. Shams-Ansari, M. Zhang, C. Wang, and для передачи квантовых состояний с компенсацией M. Lonˇcar, “Ultra-low-loss integrated visible photonics поляризационных искажений квантового канала, using thin-film lithium niobate,” Optica, vol. 6, no. 3, заявка на патент 2019117383. pp. 380–384, 2019. [57] O. Bannik, L. Gilyazov, A. Litvinov, N. Arslanov, [69] S. Tao, Q. Fang, J. Song, M. Yu, G. Lo, and D. Kwong, K. Melnik, S. Moiseev, N. Perminov, A. Yafarov, and “Cascade wide-angle y-junction 1× 16 optical power A. H. Gilmutdinov, “Device for transmitting quan- splitter based on silicon wire waveguides on silicon-on- tum states with compensation of chromatic distor- insulator,” Optics express, vol. 16, no. 26, pp. 21456– 8

21461, 2008. [81] A. Gaidash, A. Kozubov, and G. Miroshnichenko, “Meth- [70] M. Thomaschewski, V. A. Zenin, C. Wolff, and ods of decreasing the unambiguous state discrimination S. I. Bozhevolnyi, “Plasmonic monolithic lithium nio- probability for subcarrier wave quantum key distribution bate directional coupler switches,” arXiv preprint systems,” JOSA B, vol. 36, no. 3, pp. B16–B19, 2019. arXiv:1908.01858, 2019. [82] W. Jia, Y. Zhang, H. Yu, and Y. Bian, “A quantum key [71] T. Ren, M. Zhang, C. Wang, L. Shao, C. Reimer, distribution protocol based on LDPC error correcting Y. Zhang, O. King, R. Esman, T. Cullen, and M. Lonˇcar, codes,” in Proceedings of the ACM Turing Celebration “An integrated low-voltage broadband lithium niobate Conference-China, p. 124, ACM, 2019. phase modulator,” IEEE Photonics Technology Letters, [83] D. Stucki, C. Barreiro, S. Fasel, J.-D. Gautier, O. Gay, vol. 31, no. 11, pp. 889–892, 2019. N. Gisin, R. Thew, Y. Thoma, P. Trinkler, F. Vannel, , [72] J. C. Campbell, “Recent advances in avalanche photodi- and H. Zbinden, “Continuous high speed coherent one- odes,” Journal of Lightwave Technology, vol. 34, no. 2, way quantum key distribution,” Optics express, vol. 17, pp. 278–285, 2016. no. 16, pp. 13326–13334, 2009. [73] M. Avesani, D. G. Marangon, G. Vallone, and P. Villoresi, [84] I. H. L. Grande and M. A. Larotonda, “Implementation of “Source-device-independent heterodyne-based quantum a hybrid scheme for coherent plug-and-play quantum key random number generator at 17 gbps,” Nature commu- distribution,” Quantum Information Processing, vol. 17, nications, vol. 9, no. 1, p. 5365, 2018. no. 7, p. 176, 2018. [74] M. Ioannou, J. B. Brask, and N. Brunner, “How much [85] S. Sajeed, P. Chaiwongkhot, A. Huang, H. Qin, randomness can be generated from a quantum black-box V. Egorov, A. Kozubov, A. Gaidash, V. Chistiakov, device?,” arXiv preprint arXiv:1811.02313, 2018. A. Vasiliev, A. Gleim, and V. Makarov, “An ap- [75] P. Grangier and A. Auffèves, “What is quantum in quan- proach for security evaluation and certification of a com- tum randomness?,” Philosophical Transactions of the plete quantum communication system,” arXiv preprint Royal Society A: Mathematical, Physical and Engineer- arXiv:1909.07898, 2019. ing Sciences, vol. 376, no. 2123, p. 20170322, 2018. [86] A. S. Holevo, “Bounds for the quantity of informa- [76] D. Drahi, N. Walk, M. J. Hoban, W. S. Kolthammer, tion transmitted by a quantum communication channel,” J. Nunn, J. Barrett, and I. A. Walmsley, “Certified quan- Problemy Peredachi Informatsii, vol. 9, no. 3, pp. 3–11, tum randomness from untrusted light,” arXiv preprint 1973. arXiv:1905.09665, 2019. [87] A. Rukhin, J. Soto, J. Nechvatal, M. Smid, and [77] S. Molotkov, K. Kravtsov, and M. Ryzhkin, “Are there E. Barker, “A statistical test suite for random and pseu- enough decoy states to ensure key secrecy in quantum dorandom number generators for cryptographic applica- cryptography?,” Journal of Experimental and Theoretical tions,” tech. rep., Booz-Allen and Hamilton Inc Mclean Physics, vol. 128, no. 4, pp. 544–551, 2019. Va, 2001. [78] A. Huang, S.-H. Sun, Z. Liu, and V. Makarov, “Quan- [88] P. L’Ecuyer and R. Simard, “Testu01: Ac library for tum key distribution with distinguishable decoy states,” empirical testing of random number generators,” ACM Physical Review A, vol. 98, no. 1, p. 012330, 2018. Transactions on Mathematical Software (TOMS), vol. 33, [79] K. Kravtsov, I. Radchenko, S. Kulik, and S. Molotkov, no. 4, p. 22, 2007. “Relativistic quantum key distribution system with one- [89] N. Perminov, O. Bannik, L. Giliazov, K. Melnik, and way quantum communication,” Scientific reports, vol. 8, D. Y. Tarankova, “Statistical evaluation of a physical ran- no. 1, p. 6102, 2018. dom number generator,” Bulletin of the Russian Academy [80] A. Gaidash, A. Kozubov, and G. Miroshnichenko, “Coun- of Sciences: Physics, vol. 83, no. 3, pp. 374–376, 2019. termeasures for advanced unambiguous state discrimina- [90] R. R. Nigmatullin, “The statistics of the fractional mo- tion attack on quantum key distribution protocol based ments: Is there any chance to “read quantitatively” on weak coherent states,” Physica Scripta, 2019. any randomness?,” Signal Processing, vol. 86, no. 10, pp. 2529–2547, 2006.