Abstract

The UK Quantum Technology Hub in Sensors and Metrology [1] has the aim of developing integrated, small and practical cold atom systems for a range of sensor and timing applications which includes rotation, magnetism, gravity and atomic clocks. The approach is similar to that pioneered by the chip scale atomic clock [2] where atoms held in microfabricated vacuum chambers have atomic transitions excited and probed by diodes lasers [3] and photodetectors. That system used coherent population trapping for the clock transitions whilst we are aiming to first produce lasers for cooling and trapping ions inside vacuum chambers before microwave pulses or controlled lasers are used to create superposition states, recombine them and measure the interference from the final state populations. For cooling ⁸⁷Rb atoms, 780.24 nm lasers with linewidths below ~5 MHz are required whilst the lasers for controlling and measuring superposition states typically external cavity lasers have been used to achieve linewidths from 20 kHz [3] down to a few Hz [4]. Most single mode diode lasers aimed at laser cooling have used DBR gratings with regrowth [5] but this is challenging when using AlGaAs materials due to oxidation.

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