Strong parity effect of particle number in the interference fringes of Bose-Einstein condensates released from a double-well potential

Abstract

We study the parity effect of the particle number in the interference fringes of a Bose-Einstein condensate released from a double-well potential. For a coherently splitting condensate in the double-well potential, with a decoupled two-mode Bose-Hubbard model, there is well-known phase diffusion because of interatomic interactions. After a specific holding time of the double-well potential, the phase diffusion will make the interference patterns in the density distribution depend strongly on the parity of the total particle number by further overlapping two condensates. This parity effect originates from the quantized relative phase about the total particle number. The experimental scheme to observe this "even-odd" effect of the particle number is discussed.