A long-lived Zeeman trapped-ion qubit

Abstract

We demonstrate a coherence time of 2.1(1)~s for electron spin superposition states of a single trapped ${}^{40}$Ca${}^{+}$ ion. The coherence time, measured with a spin-echo experiment, corresponds to residual rms magnetic field fluctuations $\le$~2.7$\times$10${}^{-12}$~T. The suppression of decoherence induced by fluctuating magnetic fields is achieved by combining a two-layer $\mu$-metal shield, which reduces external magnetic noise by 20 to 30~dB for frequencies of 50~Hz to 100~kHz, with Sm${}_2$Co${}_{17}$ permanent magnets for generating a quantizing magnetic field of 0.37~mT. Our results extend the coherence time of the simple-to-operate spin qubit to ultralong coherence times which so far have been observed only for magnetic insensitive transitions in atomic qubits with hyperfine structure.

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Cited by in corpus (3)

• Scalable creation of long-lived multipartite entanglement
• Rotation sensing with trapped ions
• Spin readout of trapped electron qubits