Effective preparation and collisional decay of atomic condensate in excited bands of an optical lattice

TL;DR

This paper introduces a rapid method to prepare Bose-Einstein condensates in excited bands of an optical lattice and investigates their collisional decay, combining experimental demonstration with theoretical analysis.

Contribution

It presents a novel pulse sequence technique for efficiently preparing BECs in excited lattice bands and analyzes their decay dynamics both experimentally and theoretically.

Findings

Successfully prepared BEC in excited bands within tens of microseconds.

Measured and analyzed collisional decay rates of atoms in excited bands.

Theoretical calculations agree well with experimental results.

Abstract

We present a method for the effective preparation of a Bose-Einstein condensate (BEC) into the excited bands of an optical lattice via a standing-wave pulse sequence. With our method, the BEC can be prepared in either a single Bloch state in a excited-band, or a coherent superposition of states in different bands. Our scheme is experimentally demonstrated by preparing a $^{87}$Rb BEC into the $d$-band and the superposition of $s$- and $d$-band states of a one-dimensional optical lattice, within a few tens of microseconds. We further measure the decay of the BEC in the $d$-band state, and carry an analytical calculation for the collisional decay of atoms in the excited-band states. Our theoretical and experimental results consist well.