arXiv subjects

V. A. Uzunova

Publications and source records attributed to V. A. Uzunova.

4 recordsLinked to original sources

arXiv2022

Realistic photon-number resolution in generalized Hong-Ou-Mandel experiment

We consider realistic photodetection in a generalization of the Hong-Ou-Mandel experiment to the multimode case. The basic layout of this experiment underlies boson sampling -- a promising model of nonuniversal quantum computations. Peculiarities of photocounting probabilities in such an experiment witness important nonclassical properties of electromagnetic field related to indistinguishability of boson particles. In practice, these probabilities are changed from their theoretical values due to the imperfect ability of realistic detectors to distinguish numbers of bunched photons. We derive analytical expressions for photocounting distributions in the generalized Hong-Ou-Mandel experiment for the case of realistic photon-number resolving (PNR) detectors. It is shown that probabilities of properly postselected events are proportional to probabilities obtained for perfect PNR detectors. Our results are illustrated with examples of arrays of on/off detectors and detectors affected by a finite dead time.

quant-ph↗

arXiv2022

Photocounting statistics of superconducting nanowire single-photon detectors

Superconducting nanowire single-photon detectors (SNSPDs) are efficient measurement devices used for counting single photons. The field of their applications covers experimental quantum-optical studies, optical quantum computing, quantum communication, and others. After registering a photon by such a detector, the next one cannot be registered during the dead time and after that this ability is smoothly restored. We have included this feature into the photodetection theory and introduced the corresponding photocounting formula. In the regime of continuous-wave detection, the photocounting statistics nonlinearly depends on the density operator due to a memory effect of previous measurement time windows. The considered examples demonstrate the strong influence of the relaxation process and the memory effect on the resulting photocounting statistics of the SNSPDs.

quant-ph↗

arXiv2019

Continuous Aharonov--Bohm effect

The Aharonov--Bohm effect in a model system described by the generalized Schrödinger equation is considered. The scattering cross section is calculated in the standard formulation: an electron beam impinges on a long impenetrable solenoid encompassing a magnetic field. It is shown that the incident wave is scattered regardless of whether the magnetic flux through the solenoid is an integer of flux quanta whereby the scattering cross section becomes a continuously nonzero function of the total magnetic flux. The problem may find its application in investigations of the soliton-magnon interaction in the low-dimensional magnetism.

quant-ph↗

arXiv2009

Interaction of the Torque-Induced Elastic Charge and Elastic Dipole with a Wall in a Nematic Liquid Crystal

We show that the elastic charge of colloids in a nematic liquid crystal can be generated by the vector of external torque. The torque components play the role of two component charge (dyad) and give rise to the Coulomb-like potential, while their conservation law plays the role similar to that of Gauss' theorem in the electrostatics. The theory is applied to the colloid-surface interaction. A wall with homeotropic or planar director is shown to induce a repulsive 1/r^4 force on the elastic dipole. The external torque, however, induces the elastic charge in this colloid and triggers switching to the 1/r^2 repulsion.

cond-mat.soft↗