Read-out of the atomtronic quantum interference device.
A Bose-Einstein condensate confined in ring shaped lattices interrupted by a weak link and pierced by an effective magnetic flux defines the atomic counterpart of the SQUID: The Atomtronic Quantum Interference Device (AQUID). In this paper, we report on the detection of current states in the system through a self-heterodyne protocol. Following the original proposal of the NIST and Paris groups, the ring-condensate many-body wave function interferes with a reference condensate expanding from the center of the ring. We focus on the rf-AQUID which realizes effective qubit dynamics. Both the Bose-Hubbard and Gross-Pitaevskii dynamics are studied. For the Bose-Hubbard dynamics, we demonstrate that the self-heterodyne protocol can be applied, but higher order correlations in the evolution of the interfering condensates are measured to read-out of the current states of the system. We study how states with macroscopic quantum coherence can be told apart analysing the noise in the time-of-flight of the ring condensate.
Publisher URL: http://arxiv.org/abs/1707.09184