Realisation of a compact laser-pumped Rubidium frequency standard-12 with < 1×10−12 stability at 1 second

We have demonstrated a laser-optically pumped Rb clock with a short-term stability of 8×10^-13 τ^-1/2, using a simple cw pumping scheme. Further improvement towards the shot-noise limit of 2×10^-13 τ^-1/2 is expected from implementation of laser noise cancellation schemes, without need for pulsed operation or cold atoms. The main effects limiting the one-day stability of the clock, such as light shifts and clock cell temperature coefficient, are controlled and contribute <; 5×10^-15 to the clock stability at one day. A compact clock demonstrator Physics Package was realised that contains the full clock physics including the complete laser optical bench within 1.1 litres of volume. Work is in progress to demonstrate the expected long-term stability with this clock demonstrator.