Work

Modular Variable Laser Cooling for Efficient Entropy Extraction

Year: 2025

Type: article

Abstract: We propose and experimentally demonstrate a method for laser cooling an oscillator, using a two-level ancillary spin, based on sequences of spin-state-dependent displacements, followed by spin repumping. For a thermal state with mean occupation n[over ¯]≫1, the method attains a reduction to 0.632 of the initial thermal oscillator occupation for two repumps of the spin state. This is within a factor of 2.53 of the optimum that is expected due to the reduction of the oscillator entropy by 2ln(2). We show that the method, which is based on encoding the value of the modular variable of the oscillator into the spin, has a simple semiclassical description in terms of a Bayesian update. We demonstrate the method experimentally using the internal and motional states of a single trapped ion.

Source: Physical Review Letters

DOI: 10.1103/physrevlett.134.203603