Quantum Superposition States in Electromagnetic Fields
Dynamics of Formation and Destruction of Quantum Superposition States of Electromagnetic Fields and Atomic System
Tech Area / Field
- PHY-ANU/Atomic and Nuclear Physics/Physics
- PHY-OPL/Optics and Lasers/Physics
3 Approved without Funding
Institute for Physical Research, Armenia, Ashtarak-2
- University Potsdam, Institute for Physics, Germany, Potsdam
Project summaryDynamics of formation and destruction of quantum superposition states of electromagnetic fields and atomic system.
Obtaining and detection of quantum superposition states  (Schroedinger cat) is currently of great interest in quantum optics, . This interest, apart from the fundamental significance of the problem, is partially caused by possible applications of these states to practical problems arising today, such as quantum computers  and quantum algorithms of calculations [4,5], to experiments on quantum teleportation [6,7,8] (transfer of a quantum state from an object to another), and so on.
For the first time the possibility to obtain quantum superposition states of light was demonstrated in Ref.  for process of interaction of a single-mode radiation field with a non-linear (Kerr) medium. Later in Refs [10,11], it was shown that the process of one-photon absorption destroys coherence between macroscopic components of the quantum superposition state and it decays into the state of statistical mixture of these components. Then, the possibilities to obtain quantum superposition states of electromagnetic field in various non-linear processes were shown in Refs [12-17]. Experimentally quantum superposition states were observed in Refs. [18,19].
Objectives of the Project. The main objective of the proposed project is investigation of dynamics of formation and decay of quantum superposition states of electromagnetic fields and atomic systems.
Expected results. The proposed Project is concerned with the research into fundamental problems of modern quantum optics. Results obtained in the course of implementation of the project will provide new knowledge needed for understanding the quantum dynamics of unstable optical processes; a part of results may be general for the theory of selforganizing unstable systems and procedures of controlling in such systems. Elaborated algoritms and programs for study of stochastic processes can also be employed in other fields of modern science. The results related to theoretical study of quantum superposition states of electromagnetic fields and complex atomic systems are expected to be useful in future for creating new small error algorithms of calculations for quantum computers.
Competence of participators. Researchers participating in the Project are competent in theoretical investigations of interaction between electromagnetic fields and atomic systems and non-linear media. Recent works of a number of project participators (1995-1999) are concerned with theoretical study of superposition states of atomic systems and electromagnetic fields and quantum dynamics of unstable optical systems. Five selected works of each participator-researcher are presented in Sec. 3.
Realisations of purposes and problems of ISTC. The proposed Project presents wide possibilities for specialists in the field of armament to reorient their abilities on the peaceful activity. It will support the integration of Armenians scientists into the international scientific community. It will assist fundamental studies in the field of modern quantum optics; the results will extend the knowledge of the physics of unstable processes and help to find the ways to control them. It will promote the solution of international technical problems particularly those concerned with quantum computers. It will further the transition to the market economics corresponding to the civil requirements.
Scope of the Project. The proposed Project can be devided into five cycles of problems:
a) Theoretical study of quantum dynamics of unstable optical systems (third harmonic generation, four-wave mixing). Time evolution of the quantum entropy and Wigner function of interacting modes above the critical points of these systems are proposed to present, along with our results obtained earlier, a general pattern of quantum dynamics of unstable optical systems;
b) Theoretical study of how evolves destruction of coherence in the process of spontaneous decay of complex atomic systems interacting with laser fields. For such systems it is proposed to examine the dynamics of the quantum entropy of atoms, of fluctuations in steady state populations, times of correlation between various ways of spontaneous decay, the dynamics of inpidual trajectories of atomic systems, as well as evolution of the quantum entropy and Wigner function of radiation field modes;
c) Theoretical study of quantum dynamics of nonlinear optical processes in media with stochastic nonlinearities. It is envisaged in these problems to investigate the effect of high noises of the nonlinear medium on multicomponent localized states of interacting fields;
d) Theoretical study of the transition of multicomponent superposition states of electromagnetic fields to the statistical mixture of state components. It is proposed, by means of computer experiment, to examine for specific optical systems the dependence of the quantum entropy of the field on the relation between the times of localisation in state components and transition from one component to another;
e) For study of Wigner functions and quantum entropy of non-localized optical systems in the range of large numbers of photons new algorithms and programs are proposed to be produced.
Role of foreign collaborators. In the process of implementation of the Project an exchange of information on the course of its realisation is envisaged, as well as discussion of basic results of each specific problem. Also a preliminary discussion of articles ready for publication and preparing of joint articles are foreseen, as well as joint workshops.
1. E. Schroedinger, Naturwissenschaften 23, 807(1935);
2. V. Buzek, P. L. Knight, ''Quantum interference, superposition states of light and nonclassical effects'', in Progress in Optics, edited by E. Wolf (North Holland, Amsterdam, 1995);
3. Feynman R. P., Found. Phys.,16, 507 (1986);
4. P. W. Shor, in Proc. of the 35th Ann. Symp. of the Foundations of Computer Sci. (Ed S Goldwasser) (Los Alamitos, CA: IEEE Computer Society, 1994) p. 124;
5. Ekert A., Jozsa R., Rev. Mod. Pyhs. 68, 733 (1996);
6. Bouwmeester D., pan J-W, Mattle K., Eibl M., Weinfurtner H., Zeilinger A. Nature (London) 390, 575(1997);
7. Bennett C. H. et al. Phys. Rev. Lett. 70 1985 (1993);
8. Boschi D. et al. Phys. Rev. Lett. 80 1121 (1998);
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10. Ts. Ganstong, R. Tanas, Phys. Rev. A 44, 2086(1991);
11. W. Schleich, M. Perningo, L. F. Kien, Phys. Rev. A 44, 2172(1991);
12. M. Wolinsky, and H. J. Carmichael, Phys. Rev. Lett. 60, 1836(1988);
13. L. Gilles, B. M. Garraway, P. L. Knight, Phys. Rev A 49, 2785(1995);
14. K. Banaszek, P. L. Knight, Phys. Rev. A 55,2368(1997);
15. S. T. Gevorkyan, Phys. Rev. A 58, 4862(1998);
16. S. T. Gevorkyan, W. O. Chaltykyan, J. Mod. Optics 46, 1447, (1997);
17. S. T. Gevorkyan, G. Yu. Kruchkyan, N. T. Muradyan, Phys. Rev. A (in press 2000);
18. Monroe, D. M. Meekhot, B. E. King, D. J. Wineland, Science, 272,1131(1996);
19. M. W. Noel, C. R. Stroud, Phys. Rev. Lett 77, 1813(1996).
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