Coherence of a dynamically decoupled single neutral atom

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 87Rb atom. We use the two magnetic-sensitive 5S1/2 Zeeman levels |F=2,mF=−2⟩ and |F=1,mF=−1⟩ as qubit states, motivated by the possibility of coupling |F=2,mF=−2⟩ to 5P3/2 the excited state |F′=3,mF′=−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.