Proposal for a long-lived quantum memory using matter-wave optics with Bose-Einstein condensates in microgravity

Bose-Einstein condensates are a promising platform for optical quantum memories but suffer from several decoherence mechanisms, leading to short memory lifetimes. While some of these decoherence effects can be mitigated by conventional methods, density-dependent atom-atom collisions ultimately set the upper limit of the quantum memory lifetime to timescales of seconds in trapped Bose-Einstein condensates. We propose a quantum memory technique that utilizes microgravity as a resource to minimize such density-dependent effects. We show that by using optical atom lenses to collimate and refocus the freely expanding atomic ensembles, in a semi-ideal environment, the expected memory lifetime is only limited by the quality of the background vacuum. We anticipate that this method can be experimentally demonstrated in Earth-bound microgravity platforms or space missions, eventually leading to storage times of minutes and unprecedented time-bandwidth products of 10^{10}.