A long-lived Zeeman trapped-ion qubit

Autor: Ferdinand Schmidt-Kaler, Ulrich Poschinger, Claudia Warschburger, Christian Tomás Schmiegelow, H. Kaufmann, T. Ruster
Rok vydání: 2016
Předmět:
Zdroj: Applied Physics B. 122
ISSN: 1432-0649
0946-2171
Popis: We demonstrate unprecedentedly long lifetimes for electron spin superposition states of a single trapped \(^{40}\)Ca\(^+\) ion. For a Ramsey measurement, we achieve a \(1{/}\sqrt{e}\) coherence time of 300(50) ms, while a spin-echo experiment yields a coherence time of 2.1(1) s. The latter corresponds to residual effective rms magnetic field fluctuations \({\le }2.7\times 10^{-12}\,\hbox {T}\) during a measurement time of about 1500 s. 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 20–30 dB for frequencies of 50 Hz–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 trapped-ion spin qubit to ultralong coherence times which so far have been observed only for magnetic insensitive transitions in atomic qubits with hyperfine structure.
Databáze: OpenAIRE
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