Sergey N. Andrianov, Sergey A. Moiseev

Eur. Phys. J. B (2017) 90: 165.

DOI: 10.1140/epjb/e2017-80328-8

We have shown the possibility of non-Dicke superradiance for non-ideal magnon Bose-Einstein condensate (BEC) in a broadband frequency bath. Here, it is found that all the stored energy in the system of Bose-condensed magnons can be irradiated into a short pulse with a time delay caused by the strong frequency modulation of magnons due to direct inter-particle interactions in the Bose-condensed state. The last mechanism radically distinguishes this effect from the well-known Dicke superradiance of two-level atomic ensemble where the delay is connected with enhancement of the inter-atomic correlations due to exchange by virtual photons. In our case, the superradiance is the consequence of Bose-condensation in the coherent state where the particles are coupled by direct interaction. We have discussed the conditions for observation of this effect for Bose-condensed magnons in a solid-state sample with a spatial size smaller comparing with the wavelength of the emitted field. In general, we had shown that this kind of superradiance can proceed in samples with ferromagnetic type interaction. As for the antiferromagnetic ones, the effect of magnon superradiance takes place without delay.

N.M. Arslanov and S.A. Moiseev

*Quantum Electron.* **47** 783 (2017)

DOI: 10.1070/QEL16467

The possibility of enhancing the quantum efficiency of photon echo broadband quantum memory in rare-earth-ion-doped crystals with a frequency comb structure of optical transition inhomogeneous broadening is studied. We have found the optimal parameters of the frequency combs for implementing the pre-assigned quantum efficiency in the chosen spectral range of the optical transitions of rare-earth ions with real parameters. The obtained results allow the conditions to be formulated for increasing the efficiency of broadband quantum memory. The possibilities of experimental implementation of such memory are also discussed.

M.M. Minnegaliev, E.I. Baibekov, K.I. Gerasimov, S.A. Moiseev, M.A. Smirnov and R.V. Urmancheev

*Quantum Electron.* **47** 778 (2017)

The longitudinal and transverse relaxation times for a transition between hyperfine sublevels of the lower electronic states of the ^{4}I_{15/2} and ^{4}I_{9/2} multiplets of ^{167}Er^{3+} ions in ^{7}LiYF_{4} crystals have been determined for the first time using two-pulse and stimulated photon echo measurements in zero magnetic field at a temperature of 4 K. The decay of the photon echo signal has been shown to be modulated, which is tentatively attributed to the superhyperfine interaction of the ^{167}Er^{3+} ions with their ^{19}F^{−} nearest neighbours. The contributions of various types of interaction to the ultranarrow linewidth (~24 MHz) of the transition in question are discussed. Our results demonstrate that this optical transition of the ^{167}Er^{3+} ion in ^{7}LiYF_{4} crystals is potentially attractive for use in Raman quantum memory schemes.

Gerasimov, K.I., Moiseev, S.A. & Zaripov, R.B.

We have demonstrated a combination of frequency comb spin-echo protocol in a conventional microwave pulsed electron spin resonance spectrometer with gradient pulses of the external magnetic field applied for on-demand retrieval of signal microwave pulses at the required moments of time. A natural high-finesse periodic structure was used as a carrier of stored information. The structure is made out of hyperfine lines of electron spin resonance of tetracyanoethylene anion radicals in toluene at room temperature. Herein, we have also observed that using the pulses of gradient magnetic field can increase the memory capacity. The experimental results demonstrated promising opportunities for controlling electron nuclear spin coherence, which could be useful for implementation of broadband microwave or optical-microwave noise free quantum memory protocols.

Appl Magn Reson (2017)

**DOI**:10.1007/s00723-017-0892-y.

Chun Xiao Zhou, Rui Zhang, Miao Di Guo, S. A. Moiseev, and Xue Mei Su

We investigate the quantum interference effect of single photon transfer in a two-atom cavity system caused by the excitation phase. In the proposed system, the two identical atoms are firstly put into a timed state by an external single photon field. During the excitation, the atoms grasp different phases which depend on the spatial position of the atoms. Due to the strong resonant interaction between the atoms and optical cavity mode, the absorbed input photon can be efficiently transferred from the atoms to the cavity mode. We show that photon transfer is sensitive to the quantum interference caused by the excitation phases of atoms. The atomic positions can also determine the coupling constants between the atoms and cavity mode as well as the interatomic dipole–dipole interaction which causes additional interference effects on the quantum transfer. Based on the characteristics of the excitation phase, we find that it is a feasible scheme to generate a long-lived dark state and it could be useful for storage and manipulation of single photon fields by controlling the excitation phase.

J. Phys. B: At. Mol. Opt. Phys. 50125501 (2017).

К. И. Герасимов, М. М. Миннегалиев, С. А. Моисеев, T. Chanelière and A. Louchet-Chauvet

Экспериментально реализован протокол квантовой памяти, основанный на восстановлении спящего эха (ROSE) в кристалле Tm^{3+}:Y_{3}Al_{5}O_{12} в схеме с ортогональной геометрией распространения сигнального и контролирующего световых полей, которая наиболее удобна для дальнейшей реализации высокоэффективной квантовой памяти в одномодовом оптическом резонаторе. В данной схеме продемонстрирована эффективность восстановления сигнала спящего эха ~13% при времени хранения 36 mс. Также показана возможность записи и считывания последовательностей из нескольких световых импульсов. Рассмотрены достоинства и недостатки представленной схемы, предложены способы увеличения эффективности и времени хранения.

Оптика и спектроскопия т. 123, № 2 (2017)

Moiseev S.A., Gubaidullin F.F., Kirillov R.S., Latypov R.R., Perminov N.S., Petrovnin K.V., Sherstyukov O.N.

In this paper we present universal broadband multiresonator quantum memory based on the spatial-frequency combs of the microresonators coupled with a common waveguide. We find a Bragg-type impedance matching condition for the coupling of the microresonators with a waveguide field that provides an efficient broadband quantum storage. The analytical solution obtained for the microresonator fields enables sustainable parametric control of all the memory characteristics. We also construct an experimental prototype of the studied quantum memory in the microwave spectral range that demonstrates basic properties of the microwave microresonators, their coupling with a common waveguide, and independent control of the microresonator frequencies. Experimentally observed narrow lines of the microresonators confirm the possibility of multiresonator quantum memory implementation.

Phys. Rev. A **95**, 012338 (2017)

**DOI**: 10.1103/PhysRevA.95.012338

Narkis M. Arslanov, Ali A. Kamli, Sergey A. Moiseev

Investigation of light in waveguide structures is a topical modern problem that has long-standing historical roots. A *parallel-plate waveguide* is a basic model in these studies and is intensively used in numerous investigations of nano-optics, integrated circuits and nanoplasmonics. In this letter we have first found an approximate analytical solution which describes the light modes with high accuracy in the subwavelength waveguides. The solution provides a way of obtaining a clear understanding of the light properties within the broadband spectral range in the waveguide with various physical parameters. The potential of the analytical solution for studies of light fields in the waveguides of nano-optics and nanoplasmonics has also been discussed.

Laser Physics **27**, 025103 (5pp) (2017).

Moiseev, E.S., Moiseev, S.A.

We demonstrate that a photon echo can be implemented by all-optical means using an array of on-chip high-finesse ring cavities whose parameters are chirped in such a way as to support equidistant spectra of cavity modes. When launched into such a system, a classical or quantum optical signal—even a single-photon field—becomes distributed between individual cavities, giving rise to prominent coherence echo revivals at well-defined delay times, controlled by the chirp of cavity parameters. This effect enables long storage times for high-throughput broadband optical delay and quantum memory.

Laser Physics Letters, Volume 14, Number 1, 015202 (2017)

R. V. Urmancheev, K. I. Gerasimov, M. M. Minnegaliev and S. A. Moiseev

In this paper, we generalize McCall Hahn area theorem to the echo pulse irradiation in the optically depth medium where absorption line consists of several unresolved spectral optical transitions and is characterized by a symmetrical form. Some of the obtained analytical results are compared with experimental studies in Tm^{3+}:Y_{3}Al_{5}O_{12 } crystal at 793 nm.

Bulletin of RAS: Physics – 2017, Vol. 81, N. 5.

N. S. Perminov, R. S. Kirillov, R. R. Latypov, S. A. Moiseev and O. N. Sherstyukov

We study the dynamics of the interaction of microcavities that are connected to the common waveguide in the circuit multiresonator quantum memory. Were obtained optimal conditions for the implementation of quantum memory and dynamic picture of the energy exchange between different microcavities.

Bulletin of RAS: Physics – 2017, Vol. 81, N. 5.

K.I. Gerasimov, M.M. Minnegaliev, B.Z. Malkin, E.I. Baibekov, and S.A. Moiseev

We performed high-resolution magneto-optical spectroscopy of the hyperfine transitions from 4I15/2 to the 4I13/2 and 4I9/2 multiplets of 167Er3+ and 166Er3+ in an isotopically purified 7LiYF4 crystal in various external magnetic fields up to 0.7 T. The obtained experimental results are interpreted in the framework of the generalized theoretical approach. The derived model successfully explains all the experimentally observed optical hyperfine transitions by using a single set of basic parameters found for the crystal-field interaction, magnetic dipole and electric quadrupole hyperfine interactions, together with Zeeman interactions at different orientations of the external magnetic field. A number of the studied quantum transitions appears to be promising for use in Raman quantum storage at optical telecommunication wavelengths.

Phys. Rev. B **94**, 054429 (2016).

**DOI**: 10.1103/PhysRevB.94.054429

Gleim A.V., Egorov V.I., Nazarov Y.V., Smirnov S.V., Chistyakov V.V., Bannik O.I., Anisimov A.A., Kynev S.M., Ivanova A.E., Collins R.J., Kozlov S.A., Buller G.

A quantum key distribution system based on the subcarrier wave modulation method has been demonstrated which employs the BB84 protocol with a strong reference to generate secure bits at a rate of 16.5 kbit/s with an error of 0.5% over an optical channel of 10 dB loss, and 18 bits/s with an error of 0.75% over 25 dB of channel loss. To the best of our knowledge, these results represent the highest channel loss reported for secure quantum key distribution using the subcarrier wave approach. A passive unidirectional scheme has been used to compensate for the polarization dependence of the phase modulators in the receiver module, which resulted in a high visibility of 98.8%. The system is thus fully insensitive to polarization fluctuations and robust to environmental changes, making the approach promising for use in optical telecommunication networks. Further improvements in secure key rate and transmission distance can be achieved by implementing the decoy states protocol or by optimizing the mean photon number used in line with experimental parameters.

Optics express – 2016, Vol. 24, No. 3, pp. 2619-2633.

**DOI**: 10.1364/OE.24.002619

Gaidash A., Egorov V., Gleim A.

We discuss a method for revealing a photon-number-splitting (PNS) attack in a quantum key distribution (QKD) system, which is based on analyzing the statistical distribution of photon numbers detected in each time interval. A relation for estimating the difference between the expected photon-number distribution and the one appearing in the course of a PNS attack is derived. An equation defining the minimum number of counts necessary for revealing the attack with desired probability is given. Formulas for calculating the amount of raw keys known to an illegitimate user due to a PNS attack are obtained depending on the system’s total loss. The main advantage of the method is the possibility of using it in QKD systems without significant modifications in the protocol or experimental setup.

Journal of the Optical Society of America B: Optical Physics – 2016, Vol. 33, No. 7, pp. 1451-1455.

Ivanova A.E., Chivilikhin S.A., Gleim A.V.

In this paper mathematical description of using of fiber Y-splitter and optical splitter with two input and two output ports in quantum random number generation systems were obtained.

Journal of Physics: Conference Series – 2016, Vol. 735, No. 1, pp. 012077.

**DOI**: 10.1088/1742-6596/735/1/012077

Gaidash A.A., Kozubov A.V., Egorov V.I., Gleim A.V.

Subcarrier wave quantum key distribution systems demonstrate promising capabilities for secure quantum networking. However for this class of devices no implementation of secure decoy states protocol was developed. It leaves them potentially vulnerable to photon-number splitting attacks on quantum channel and limiting the key distribution distance. We propose a practical solution to this problem by calculating the required parameters of light source and modulation indices for signal and decoy states in a subcarrier wave system and describing the corresponding experimental scheme.

Journal of Physics: Conference Series – 2016, Vol. 741, No. 1, pp. 012090.

**DOI**: 10.1088/1742-6596/741/1/012090

Moiseev, E.S., Moiseev, S.A.

We have proposed a compact scheme of quantum random access memory (qRAM) based on the impedance matched multi-qubit photon echo quantum memory incorporated with the control four-level atom in two coupled QED cavities. A set of matching conditions for basic physical parameters of the qRAM scheme that provides an efficient quantum control of the fast single photon storage and readout has been found. In particular, it has been discovered that the efficient qRAM operations are determined by the specific properties of the excited photonic molecule coupling the two QED cavities. Herein, the maximal efficiency of the qRAM is realized when the cooperativity parameter of the photonic molecule equals to unity that can be experimentally achievable. We have also elaborated upon the new quantum address scheme where the multi-time-bin photon state is used for the control of the four-level atom during the readout of the photonic qubits from the quantum memory. The scheme reduces the required number of logical elements to one. Experimental implementation by means of current quantum technologies in the optical and microwave domains is also discussed.

Journal of Modern Optics, Volume 63, Issue 20, pp 2081-2092(2016)

**DOI: **10.1080/09500340.2016.1182222

Gerasimov, K.I., Minnegaliev, M.M., Malkin, B.Z., Baibekov, E.I., **Moiseev**, S.A.

We performed high-resolution magneto-optical spectroscopy of the hyperfine transitions from I15/24 to the I13/24 and I9/24 multiplets of Er3+167 and Er3+166 in an isotopically purified LiYF47 crystal in various external magnetic fields up to 0.7 T. The obtained experimental results are interpreted in the framework of the generalized theoretical approach. The derived model successfully explains all the experimentally observed optical hyperfine transitions by using a single set of basic parameters found for the crystal-field interaction, magnetic dipole and electric quadrupole hyperfine interactions, together with Zeeman interactions at different orientations of the external magnetic field. A number of the studied quantum transitions appears to be promising for use in Raman quantum storage at optical telecommunication wavelengths.

Phys. Rev. B, Volume 94, Issue 5, 054429 (2016)

**DOI:**** **10.1103/PhysRevB.94.054429

Moiseev S. A. , Andrianov S. N.

A quantum transistor based quantum computer where the multiqubit quantum memory is a component of the quantum transistor and, correspondingly, takes part in the performance of quantum logical operations is considered. Proceeding from the generalized Jaynes–Cummings model, equations for coefficients of the wave function of the quantum system under consideration have been obtained for different stages of its evolution in processes of performing logical operations. The solution of the system of equations allows one to establish requirements that are imposed on the parameters of the initial Hamiltonian and must be satisfied for the effective operation of the computer; it also demonstrates the possibility of a universal set of quantum operations. Thus, based on the proposed approach, the possibility of constructing a compact multiatomic ensemble based on quantum computer using a quantum transistor for the implementation of two-qubit gates has been demonstrated.

Optics and Spectroscopy, Volume 121, Issue 6, pp 886–896(2016)

**DOI**: 10.1134/S0030400X16120195

S. A. Moiseev, and V. A. Skrebnev

We propose an alternate pulse sequence for dynamical averaging of the dipole-dipole interactions and inhomogeneity of the magnetic fields in the nuclear-spin system. The sequence contains a short cycle of the periodic resonant pulse excitation that offers new possibilities for implementing the long-lived multiqubit quantum memory on the condensed spin ensembles that are so important for the construction of a universal quantum computer and long-distance quantum communications.

Phys. Rev. A 91, 022329 (2015)

**DOI**: 10.1103/PhysRevA.91.022329

Agus Muhamad Hatta, Ali A. Kamli, Ola A. Al-Hagan and Sergey A. Moiseev

Slow light with electromagnetically induced transparency (EIT) in the core of optical bre containing three-level atoms is investigated. The guided modes are treated in the weakly guiding approximation which renders the analysis into manageable form. The transparency window and permittivity prole of the core due to the strong pump eld in the EIT scheme is calculated. For a specic permittivity prole of the core due to EIT, the propagation constant of the weak signal eld and spatial shape of fundamental guided mode are calculated by solving the vector wave equation using the nite dierence method. It is found that the transparency window and slow light eld can be controlled via the optical bre parameters. The reduced group velocity of slow light in this conguration is useful for many technological applications such as optical memories, eective control of single photon elds, optical buer and delay line.

S A Moiseev and V A Skrebnev

We have proposed a new pulse sequence for the dynamical decoupling of decoherence effects in the ensemble of nuclear spins. The sequence provides a symmetric cycle that offers a strong suppression of the decoherence effects caused by the dipole–dipole interactions and the inhomogeneous local magnetic fields in nuclear spin ensemble dynamics. We have discussed a potential of the proposed pulse sequence for the long-lived storage of the multi-qubit quantum states.

J. Phys. B: At. Mol. Opt. Phys. 48 (2015) 135503 (5pp)

**DOI**: 10.1088/0953-4075/48/13/135503

S. A. Moiseev, A. I. Sidorova and B. S. Ham

We have studied stationary and quasistationary signal light pulses in cold -type atomic media driven by counterpropagating control laser fields at the condition of electromagnetically induced transparency. By deriving a dispersion relation we present spectral and temporal properties of the signal light pulse and a significant influence of atomic decoherence on the coupled stationary light pulses for spatial splitting. Finally we discuss quasistationary light pulse evolution characterized by frozen spatial spreading for a robust coherent control of slow light pulses.

Phys. Rev. A 89, 043802 (2014)

**DOI**: 10.1103/PhysRevA.89.043802

K. I. Gerasimov, S. A. Moiseev, V. I. Morosov, and R. B. Zaripov

The controllable storage and on demand retrieval of the microwave pulses by using the photon echo quantum memory approach based on a spin frequency comb of inhomogeneous broadening (SFC- protocol) have been demonstrated. We have used an electron-nuclear spin ensemble of tetracyanoethylene anion radicals in toluene which has a natural periodic structure of narrow electron-spin resonance (ESR) hyperfine lines. On-demand retrieval of the stored field has been realized by using two pulses of the magnetic field gradient of an opposite polarity which hold the electron spins in a dephased excited state during the storage time. The obtained experimental results demonstrate promising properties for coherent controlling the electron-nuclear spin ensemble of radicals in liquid that could be useful for implementation of room-temperature broadband quantum memory.

Proc. of SPIE Vol. 9533 953310-1

**DOI**: 10.1117/12.2185472

S. N. Andrianov and S. A. Moiseev

Recently, great progress has been made in the creation of a solid-state quantum computer using superconducting qubits on Cooper pairs of charged electrons.However, this approach hasmet limitations due to decoherence effects caused by the strong Coulomb interaction of the superconducting qubitwith the environment. Here, we propose the solution of this problem by switching to another Bose-Einstein condensate (BEC), uncharged long-livedmagnons, wherein the magnon BEC qubit can be realized due to themagnon blockade isolating a pair of themagnon condensate energy levels in the mesoscopic and nanoscopic ferromagnetic dielectric sample.We demonstrate the singlequbit gates by operating quantum transition between these states in the external microwave field.We also consider implementation of the two-qubit gates by using the interaction between such magnon BEC qubits due to exchange by virtual photons in a microwave cavity. Finally, we discuss the condition for long-lived magnon BEC qubits, a scalable architecture, and promising advantages of the multiqubit quantum computer based on the magnon qubit.

Phys. Rev. A 90, 042303 (2014)

**DOI**: 10.1103/PhysRevA.90.042303

K. I. Gerasimov, S. A. Moiseev, V. I. Morosov and R. B. Zaripov

We have demonstrated the storage of electromagnetic pulses by exploiting a spin-echo quantum memory protocol. Therein, we have used an electron-nuclear spin ensemble of tetracyanoethylene anion radicals in toluene which has a natural periodic structure of narrow electron-spin resonance (ESR) hyperfine lines. Robust storage up to three temporal modes has been achieved with storage time ∼1 μs at room temperature on a conventional pulsed ESR spectrometer. On-demand retrieval of the stored field has been realized by holding the electron spins in a dephased state during the storage time. A longer storage time and the highest overall finesse ∼20 of the ESR spectrum have been attained by using multipulse dynamical decoupling of the electron spins from the noisy environment. The obtained experimental results suggest that the electron-nuclear spin ensemble of radicals in liquid should be a promising system for the room-temperature quantum memory.

Phys. Rev. A 90, 042306 (2014)

**DOI**: 10.1103/PhysRevA.90.042306

Sergey N. Andrianov, Vladimir V. Bochkarev, and Sergey Moiseev

We have analysed the kinetics of Bose-Einstein condensed (BEC) magnons after pulsed excitation in a ferromagnet at room and low temperatures. For this purpose, we have derived the kinetic

equations using the nonequilibrium statistical operator method to describe the general form of the interactions in the magnon system. On the basis of this approach, we have analysed the nonlinear properties of the magnon BEC kinetics caused by interactions with magnon reservoir modes and phonons. We have found that formation of a quasi-stationary BEC magnon state is possible not only at room temperature but also at low temperatures, where the magnon-phonon interaction leads to formation of a residual BEC state with magnon population much larger than at room temperature. It was also observed that a moderately strong four-particle part of the magnon-magnon interaction violating the number of magnons is sufficient to facilitate magnon BEC formation. The predicted long-lived magnon BEC state could be promising for realisation of macroscopic qubits.

Eur. Phys. J. B (2014) 87: 128