A Dynamic Locking System for Bose-Einstein Condensation and Four-wave Mixing Experiments

A spin-exchange exchange collision in an F=1 spinor Bose-Einstein Condensate (BEC) converts pairs of atoms with magnetic quantum numbers mF = 0 into entangled pairs with mF = +1 and mF = -1. In order to perform a below shot-noise measurement of the spin populations in our sodium spinor BEC, we plan to image the gas using entangled twin-beams of light. The entangled beams are generated via a nonlinear four-wave mixing (FWM) process. To study spin dynamics with such a low noise measurement, it is important to ensure that the lasers used for both the BEC and the FWM are locked to their respective wavelengths appropriately. The laser used for laser cooling and trapping is locked on the sodium D2 line, whereas the FWM process is implemented on the D1 line. Therefore, a dynamic laser locking system for BEC and FWM experiments is necessary. Our locking system will allow the laser to be locked on or in-between the sodium lines, by adjusting the RF driving frequency of an acousto-optic modulator set up in a double-passing configuration within several hundred MHz. In this poster, we present the design and apparatus for our dynamic laser locking system for both the spinor BEC and FWM systems.