State detection using coherent Raman repumping and two-color Raman transfers

TL;DR

This paper introduces a novel state detection method using coherent Raman repumping and two-color Raman transfer, achieving high efficiency and fidelity in detecting quantum states of trapped ions.

Contribution

The work demonstrates a new technique combining coherent Raman repumping with two-color Raman transfer for improved quantum state detection in trapped ions.

Findings

Achieved 89.6% single-shot detection efficiency in 1 ms.

Demonstrated 100% fidelity in Raman state transfer.

Effectively eliminated unwanted dark states during detection.

Abstract

We demonstrate state detection based on coherent Raman repumping and a two-color Raman state transfer. The Raman coupling during detection selectively eliminates unwanted dark states in the fluorescence cycle without compromising the immunity of the desired dark state to off-resonant scattering. We demonstrate this technique using $^{137}\mathrm{Ba}^+$ where a combination of Raman coupling and optical pumping leaves the $D_{3/2}$ $\ket{F"=3,m_F"=3}$ metastable state optically dark and immune to off-resonant scattering. All other states are strongly coupled to the upper $P_{1/2}$ levels. We achieve a single shot state-detection efficiency of $89.6(3)%$ in a $1\mathrm{ms}$ integration time, limited almost entirely by technical imperfections. Shelving to the $\ket{F"=3,m_F"=3}$ state before detection is performed via a two-color Raman transfer with a fidelity of $1.00(3)$.