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Ya. Kazakov A.,St. Petersburg State University of Aerospace Instrumentation
International Journal of Quantum Information | Year: 2010

We discuss "partial" quantum cloning of pure two-partite states, where only the "part" of the initial state related to one qubit is copied. The same approach gives the possibility of designing a quantum copying machine for mixed qubit states. © 2010 World Scientific Publishing Company. Source

Fedorenko S.V.,St. Petersburg State University of Aerospace Instrumentation
IEEE Signal Processing Letters | Year: 2016

A novel method for computing the discrete Fourier transform (DFT) over a finite field based on the Goertzel-Blahut algorithm is described. The novel method is currently the best one for computing the DFT over even extensions of the characteristic two finite field, in terms of multiplicative complexity. © 2016 IEEE. Source

Blagoveshchenskii D.V.,St. Petersburg State University of Aerospace Instrumentation
Geomagnetism and Aeronomy | Year: 2013

The result of the effect of magnetospheric storms and substorms on the ionosphere (the so-called main effect) has been studied. The effect consists in that the critical frequency and altitude of the F region vary specifically during a disturbance. The critical frequency first increases before the storm (substorm) active phase, then decreases during the active phase, and increases again after this phase. On the contrary, the F region altitude increases during the active phase and decreases after this phase. An approach to the short-term (2-3 h) prediction of the development of storms (substorms) as the main disturbed space weather elements has been proposed. © 2013 Pleiades Publishing, Ltd. Source

Farafonov V.G.,St. Petersburg State University of Aerospace Instrumentation
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2013

We have constructed a solution to the problem of scattering by a nonconfocal multilayer particle. The main difficulty was to join expansions constructed in two spheroidal systems on either side of each boundary. As a result of a detailed consideration of relations between scalar wave spheroidal and spherical functions, we have succeeded in finding a representation of the former in terms of the latter and vice versa. In the final form, the joining of solutions is described by only one matrix, which depends on coefficients of representations of angle spheroidal functions in terms of associated Legendre functions of the first kind. Since the problem has been solved using an approach that involves the method of extended boundary conditions, the dimension of the system for numerical determining unknown coefficients is equal to the number of terms that are taken into account in field expansions and does not depend on the number of particle layers. Previously performed numerical calculations for confocal particles have shown a very high efficiency of the algorithm not only for particles that are close to spheres in shape, but also for strongly prolate and strongly oblate spheroids. In addition, the algorithm makes it possible to calculate optical properties of particles that have dozens of layers. © 2013 Pleiades Publishing, Ltd. Source

Fedorenko S.V.,St. Petersburg State University of Aerospace Instrumentation
IEEE Transactions on Signal Processing | Year: 2015

A normalized cyclic convolution is a cyclic convolution when one of its factors is a fixed polynomial. Herein, a novel method for constructing a normalized cyclic convolution over a finite field is introduced. This novel method is the first constructive and best known method for even lengths. This method can be applied for computing discrete Fourier transforms over finite fields. © 2015 IEEE. Source

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