Nonlinear effects in tunneling

Victor Fleurov

School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 69978 Tel Aviv, Israel

Discrete nonlinear Schroedinger (DNLS) equation is currently a toy model allowing for investigation of dynamics of discrete quantum breathers. This is often done by means of the number representation. Otherwise, DNLS allows for a cannonical transformation, which makes WKB analysis of tunneling between classical isolated periodic orbits (IPO) possible. Considering tunneling between IPO's for general type of systems, which not necesserilly are of a DNLS type, the angle-action representation is used in order to make a WKB analysis possible. It is demonstrated how tunneling amplitude between IPO's in a system of two coupled anharmonic oscillators can be calculated.