Many-body selective destruction of tunneling in a bosonic junction

Abstract

A scheme for selective coherent destruction of tunneling (CDT) of strongly interacting bosons in a symmetric double-well potential, in which an arbitrarily and a priori prescribed number of bosons are allowed to tunnel from one well to the other one is theoretically proposed. As compared to the many-body CDT scheme recently proposed by Gong, Molina, and Hänggi [Phys. Rev. Lett. 103, 133002 (2009)] and based on a fast modulation of the self-interaction strength, the method suggested in this work exploits the traditional method of fast modulation of the energy level unbalance between the two wells by an external ac force.The physics of strongly driven quantum systems has attracted a great interest in different areas of science for many years [1]. The dynamics of quantum systems can be deeply (nonperturbatively) modified by the exposition to strong time-dependent driving fields, leading to novel interesting phenomena. Among others, coherent destruction of tunneling (CDT) [2] and dynamic localization (DL) [3] represent seminal results in the dynamical control of quantum tunneling by strong fields. CDT and DL have been actively studied in several fields of physics and observed in a few recent experiments [4][5][6][7]. In particular, in Ref.[6] a direct observation of single-particle CDT for matter waves in a periodically driven double-well potential was reported. For a single-particle problem, CDT is traditionally realized by direct modulation of the energy unbalance between the two bare levels of the double-well potential [1,2]. This can be achieved by either application of an external sinusoidal force or by sinusoidally shaking the double-well potential [1]. Many-body generalizations of CDT have attracted considerable interest in recent years (see, for instance, Refs. [8-15] and references therein), and interesting novel effects have been predicted in the framework of Bose-Hubbard or mean-field models of many-particle tunneling. In particular, in Ref.[13], Gong, Molina and Hänggi have recently proposed a novel route to CDT by considering a monochromatic fast modulation of the self-interaction strength of a bosonic system in a double-well potential (a bosonic junction [16][17][18]) in the framework of a standard Bose-Hubbard model. In this scheme the modulation can be tuned in such a way that only an arbitrarily, a priori prescribed number of particles are allowed to tunnel from one well to the other one. In this Brief Report we consider the coherent control of quantum tunneling in a bosonic junction by the traditional scheme based on the application of an external sinusoidal force (or by sinusoidally shaking the double-well potential), and show that for strongly interacting bosons the selective many-body CDT result of Ref. [13] can be realized without modulation of the self-interaction energy.The starting point of our analysis is provided by a standard two-mode Bose-Hubbard Hamiltonian, which describes the tunneling dynamics of bosons in a symmetric double-well potential driven by an external ac force. The Hamiltoni...

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