Kocharovsky Vitaly

Leading scientist, Dr.Sc.

Education:

1997 – Dr. Habilitation Degree in Physics and Mathematics awarded by the Highest Attestation Commission of Russia after the defence of thesis at IAP RAS

1986 – Ph.D. in Physics and Mathematics (Radiophysical Research Institute, Nizhny Novgorod)

1978 – M.S. in Physics and Mathematics (with the distinction, Nizhny Novgorod State University)

Scope of professional interests:

Quantum and classical field theory, Nonlinear waves and oscillations, Radiation transfer, Radiophysics, Plasma physics, Solid state physics, Semiconductor physics, Superconductivity, Bose-Einstein condensation, Phase transitions, Quantum optics, Laser physics, High-energy particles physics, Astrophysics, Cosmology, Gravity

Professional career:

2002–Date Professor, Associate Professor, Department of Physics and Astronomy, Texas A&M University, USA

2001–2001 Visiting Associate Professor, Department of Physics, Texas A&M University

1998–2001 Associate Research Scientist, Department of Physics, Texas A&M University

1996–Date Leading Researcher, Institute of Applied Physics, Russian Academy of Science

1986–1996 Senior Researcher, Institute of Applied Physics, Russian Academy of Science

1978–1986 Researcher, Institute of Applied Physics, Russian Academy of Science

Membership in professional organizations:

Member of the International Astronomical Union, IAU (elected in 2000)

Member of the American Physical Society (APS) since 1999

Member of the Committee on Space Research (COSPAR) since 1997 Member of the Optical Society of America (OSA) since 1996

Pedagogical activities:

Professor, Department of Physics and Astronomy, Texas A&M University, USA (General physics courses for undergraduate students)

Publications:

250

Most significant papers and results:

V.V.Zheleznyakov, Vl.V.Kocharovsky, V.V.Kocharovsky / Linear coupling of electromagnetic waves in inhomogeneous weakly anisotropic media // Sov. Phys. Usp., 1983, v.26, N 10, pp.877-905.

V.V.Zheleznyakov, Vl.V.Kocharovsky, V.V.Kocharovsky / Polarization waves and superradiance in active media // Sov. Phys. Usp., 1989, v.32, N 10, pp.835-870.

Kalinin P.A., Kocharovsky V.V., Kocharovsky Vl.V. / Lasing threshold in traps for bose-condensation of dipolar excitons // Solid State Communications. - 2012. - Т. 152. № 12. - С. 1008-1011.

We consider exciton recombination lasing in heterostructure traps for Bose–Einstein condensation of dipolar excitons. We show that such structures suit well for class D lasers where cavity decay strongly exceeds polarization decay. We evaluate lasing threshold taking into account specific inhomogeneous broadening of the exciton spectral line owing to Bose–Einstein condensation phenomenon under quasi-equilibrium conditions. It is found that narrowing of the exciton momentum distribution just before the condensation onset considerably lowers lasing threshold. At the same time, it is pointed out that a subsequent formation of condensate itself does not help lasing much. We conclude that it is possible to achieve lasing on polariton modes in nowadays experiments aimed on Bose–Einstein condensation of excitons.

Kocharovsky V.V., Kocharovsky Vl.V., Martyanov V.Ju. / Self-consistent current sheets and filaments in relativistic collisionless plasma with arbitrary energy distribution of particles // PRL, 2010, v. 104 (n. 21), p. 215002.

A new class of self-consistent planar current sheets and cylindrical current filaments with a functional freedom for the resultant spatial profiles is found analytically for collisionless plasma. Invariants of particle motion are employed to obtain exact stationary solutions of Vlasov-Maxwell equations for arbitrary energy distribution of particles. This method automatically takes into account complicated particle motion in a self-consistent magnetic field, can be equally well applied to relativistic and nonrelativistic plasma, and yields a much wider class of solutions as compared to models of the Harris-Bennett type and their known generalizations. We discuss typical analytical solutions and general properties of magnetostatic neutral structures: spatial scales, magnitudes of current and magnetic field, degree of anisotropy of particle distributions, and possible equipartition of magnetic and particle energies.

V.V. Kocharovsky, Vl.V. Kocharovsky / Analytical theory of mesoscopic Bose-Einstein condensation in an ideal gas // Phys. Rev. A, 2010, v. 81, p. 033615.

We find the universal structure and scaling of the Bose-Einstein condensation (BEC) statistics and thermodynamics (Gibbs free energy, average energy, heat capacity) for a mesoscopic canonical-ensemble ideal gas in a trap with an arbitrary number of atoms, any volume, and any temperature, including the whole critical region. We identify a universal constraint-cutoff mechanism that makes BEC fluctuations strongly non-Gaussian and is responsible for all unusual critical phenomena of the BEC phase transition in the ideal gas. The main result is an analytical solution to the problem of critical phenomena. It is derived by, first, calculating analytically the universal probability distribution of the noncondensate occupation, or a Landau function, and then using it for the analytical calculation of the universal functions for the particular physical quantities via the exact formulas which express the constraint-cutoff mechanism. We find asymptotics of that analytical solution as well as its simple analytical approximations which describe the universal structure of the critical region in terms of the parabolic cylinder or confluent hypergeometric functions. The obtained results for the order parameter, all higher-order moments of BEC fluctuations, and thermodynamic quantities perfectly match the known asymptotics outside the critical region for both low and high temperature limits. We suggest two- and three-level trap models of BEC and find their exact solutions in terms of the cutoff negative binomial distribution (which tends to the cutoff gamma distribution in the continuous limit) and the confluent hypergeometric distribution, respectively. Also, we present an exactly solvable cutoff Gaussian model of BEC in a degenerate interacting gas. All these exact solutions confirm the universality and constraint-cutoff origin of the strongly non-Gaussian BEC statistics. We introduce a regular refinement scheme for the condensate statistics approximations on the basis of the infrared universality of higher-order cumulants and the method of superposition and show how to model BEC statistics in the actual traps. In particular, we find that the three-level trap model with matching the first four or five cumulants is enough to yield remarkably accurate results for all interesting quantities in the whole critical region. We derive an exact multinomial expansion for the noncondensate occupation probability distribution and find its high-temperature asymptotics (Poisson distribution) and corrections to it. Finally, we demonstrate that the critical exponents and a few known terms of the Taylor expansion of the universal functions, which were calculated previously from fitting the finite-size simulations within the phenomenological renormalization-group theory, can be easily obtained from the presented full analytical solutions for the mesoscopic BEC as certain approximations in the close vicinity of the critical point.

Y.D. Jho, X. Wang, D.H. Reitze, J. Kono, A.A. Belyanin, V.V. Kocharovsky, Vl.V. Kocharovsky, and G.S. Solomon / Cooperative recombination of electron-hole pairs in semiconductor quantum wells under quantizing magnetic field // Phys. Rev. B, 2010, v. 81, n.15, p. 155314.

We present results of detailed investigations of light emission from semiconductor multiple quantum wells at low temperatures and high magnetic fields excited by intense femtosecond laser pulses. The intensity and linewidth as well as the directional and statistical properties of photoemission strongly depended on the magnetic field strength and pump laser fluence. We also investigated the effects of spot size, temperature, excitation geometry, and excitation pulse width on the emission properties. The results suggest that the initially incoherent photoexcited electron-hole pairs spontaneously form a macroscopic coherent state upon relaxation into the low-lying magnetoexcitonic states, followed by the emission of a superfluorescent burst of radiation. We have developed a theoretical model for superfluorescent emission from semiconductor quantum wells, which successfully explained the observed characteristics.

Derishev E.V., Aharonian F.A., Kocharovsky V.V., Kocharovsky Vl.V. / Particle acceleration through multiple conversions from a charged into a neutral state and back // Phys. Rev. D. 2003. V. 68. N 4. P. 043003.

We propose a new means for a quick and efficient acceleration of protons and/or electrons in relativistic bulk flows. The maximum attainable particle energies are limited either by radiative losses or by the condition of confinement in the magnetic field. The new mechanism takes advantage of a conversion of particles from the charged state (protons, electrons or positrons) into a neutral state (neutrons or photons) and back. In most cases, the conversion is photon induced and requires the presence of intense radiation fields, but under special circumstances the converter acceleration mechanism may operate via other charge-changing reactions, for example, inelastic nucleon-nucleon collisions. As in the traditional, “stochastic” (or diffusive) acceleration models, the acceleration cycle in the proposed scenario consists of the escape of particles from the relativistic flow followed by their return back after deflection from the ambient magnetic field. The difference is that the charge-changing reactions, which occur during the cycle, allow accelerated particles to increase their energies in each cycle by a factor much larger than 2 and usually roughly equal to the bulk Lorentz factor squared. The emerging spectra of accelerated particles can be very hard and their maximum energy in some cases is larger than in the standard mechanism. This significantly reduces the required energy budget of the sources of the highest-energy particles observed in cosmic rays. The proposed acceleration mechanism has a distinctive feature—it unavoidably creates neutral beams, consisting of photons, neutrinos, or neutrons, whose beam pattern may be much broader than the inverse Lorentz factor of the relativistic flow. Also, the new mechanism may serve as an efficient means of transferring the energy of bulk motion to gamma radiation and, if the accelerated particles are nucleons, inevitably produces high-energy neutrinos at a relative efficiency approaching *?*50%.

Belyanin A.A., Capasso F., Kocharovsky V.V., Kocharovsky VI.V., Scully M.O. / Infrared generation in low-dimensional semiconductor heterostructures via quantum coherence // Phys. Rev. A. 2001. V. 63. N 5. P. 538031-(8).

A scheme for infrared generation without population inversion between subbands in quantum-well and quantum-dot lasers is presented. The scheme is based on the resonant nonlinear mixing of the optical laser fields on the two interband transitions that are generated in the same active region and that serve as the coherent drive for the infrared field. This mechanism for frequency down-conversion does not rely upon any *ad hoc* assumptions of long-lived coherences in the semiconductor active medium, and it should work efficiently at room temperature with injection current pumping. For optimized waveguide and cavity parameters, the intrinsic efficiency of the down-conversion process can reach the limiting quantum value corresponding to one infrared photon per one optical photon. Due to the parametric nature of infrared generation, the proposed inversionless scheme is especially promising for long-wavelength (far-infrared) operation.

Derishev E.V., Kocharovsky V.V., Kocharovsky Vl.V. / The neutron component in fireballs of gamma-ray bursts: dynamics and observable imprints // The Astrophysical Journal. 1999. V. 521. N 2, PART 1. P. 640-649.

We analyze the dynamics of a neutron-proton relativistic wind, paying particular attention to fireballs of cosmological gamma-ray bursts (GRBs). Specific effects of the neutron component depend on whether the final Lorentz factor of a plasma wind exceeds some critical value or not. In the first case, velocity decoupling of the neutron and proton flows takes place, giving rise to an electromagnetic cascade induced by pion production in inelastic collisions of nucleons. Otherwise, all nucleons in the wind behave as a single fluid. In both cases neutrons can strongly influence a GRB by changing the dynamics of a shock initiated by protons in the surrounding medium. Conditions for the decoupling of the neutron flow as well as observational consequences of the resulting pion-induced cascade are discussed, including preburst of high-energy photons and neutrinos and annihilation afterglow of a huge number of ejected electron-positron pairs. The critical value of the Lorentz factor is estimated to lie in the range expected for cosmological GRBs, so there possibly exist two different populations of bursts. A number of tests for decoupling of the neutron flow is suggested. The results obtained for the radiation-driven wind allow straightforward generalization for winds driven by other mechanisms, e.g., for the MHD winds.

V.V.Kocharovsky, Vl.V.Kocharovsky / Self-consistent infrared & ultraviolet asymptotically free unitary renormalizable theory of quantum gravity and matter fields // Foundations of Physics, 1996, v.26, n.2, pp.243-256.

*A way to a self-consistent physically acceptable formulation of quantum gravity field theory is found. The simplified model of quantized conformally-flat gravity and a massive scalar field is analyzed**.*