Coherence of a dynamically decoupled single neutral atom

Abstract

Long qubit coherence and efficient atom–photon coupling are essential for advanced applications in quantum communication. One technique to maintain coherence is dynamical decoupling (DD), where a periodic sequence of refocusing pulses is employed to reduce the interaction of the system with the environment. We experimentally study the implementation of DD on an optically trapped, spin-polarized 87 R b atom. We use the two magnetic-sensitive 5 S 1 / 2 Zeeman levels | F = 2 , m F = − 2 ⟩ and | F = 1 , m F = − 1 ⟩ as qubit states, motivated by the possibility of coupling | F = 2 , m F = − 2 ⟩ to 5 P 3 / 2 the excited state | F ′ = 3 , m F ′ = − 3 ⟩ via a closed optical transition. With more refocusing pulses in the DD technique, we manage to extend the coherence time from 38(3) µs to around 7 ms. We also observe a strong correlation between the motional states of the atom and the qubit coherence after the refocusing, which can be used as a measurement basis to resolve trapping parameters.