Yanagisawa, MasahiroJames, Matthew2015-12-10July 6-119781123478902http://hdl.handle.net/1885/54079In this paper we present a multi-loop measurement feedback control scheme to improve atom laser coherence. The first loop (proposed by Thomsen and Wiseman, 2002) aims to cancel the decohering effects of the nonlinear atom-atom interactions via direct measurement feedback. However, there are nonlinear interactions with the optical probe field used in the measurement scheme which may also contribute to a degradation in atom laser performance. Accordingly, we introduce a second feedback loop to implement a LQG controller to reduce these effects. The multi-loop design achieves improved atom laser coherence.Keywords: Atom laser; Atom-atom interaction; Control schemes; Direct measurement; Feed-back loop; Loop design; Loop feedback; LQG controller; Measurement feedback; Nonlinear interactions; Optical probe; Stochastic control; Atoms; Feedback control; Lasers; Stochasti Stochastic control200810.3182/20080706-5-KR-1001.07152016-02-24