In usual situations, dissipation is considered to be a serious enemy to quantum mechanical systems as it leads to a rapid decay of the coherence.  Surprisingly, however, an appropriately designed coupling between the system and the reservoir can drive the system into a given pure state.  Recently, we started working on such dissipative quantum state engineering and have found a method to create phase- and number-squeezed states in two-mode Bose systems using dissipation [1].  Our method can be applied to any two-state Bose system such as cold Bose gases in a double-well potential described by the two-site Bose-Hubbard Hamiltonian.  The extension of our formalism to an optical lattice gives control of the phase boundaries of the steady-state phase diagram, and we discover a new phase characterized by a non-zero condensate fraction and thermal-like particle number statistics.  In this talk, I will first introduce the basic notions of the state engineering by dissipation and then explain our recent work [1].

Reference

[1] G. Watanabe and H. Makela, arXiv:1101.4845 [cond-mat.quant-gas].

Click to download: Presentation File