Fast cooling of trapped ion in strong sideband coupling regime

Trapped ion in the Lamb-Dicke (LD) regime with the LD parameter eta MUCH LESS-THAN 1 can be cooled down to its motional ground state using sideband cooling. Standard sideband cooling works in the weak sideband coupling (WSC) limit, where the sideband coupling strength is small compared to the natural linewidth gamma of the internal excited state, with a cooling rate much less than gamma. Here we consider cooling schemes in the strong sideband coupling (SSC) regime, where the sideband coupling strength is comparable or even greater than gamma. We derive analytic expressions for the cooling rate and the average occupation of the motional steady state in this regime, based on which we show that one can reach a cooling rate which is proportional to gamma, while at the same time the steady state occupation increases by a correction term proportional to eta(2) compared to the WSC limit. We demonstrate with numerical simulations that our analytic expressions faithfully recover the exact dynamics in the SSC regime.

Automated summary

The paper discusses cooling schemes in the strong sideband coupling (SSC) regime, deriving analytic expressions for the cooling rate and the average occupation of the motional steady state. Numerical simulations demonstrate that the analytic expressions accurately recover the exact dynamics in the SSC regime.