Coherent quantum oscillations and echo measurements of a Si charge qubit

Shi, Zhan and Simmons, C. B. and Ward, Daniel R. and Prance, Jonathan and Mohr, R. T. and Koh, Teck Seng and Gamble, John King and Wu, Xian and Savage, D. E. and Lagally, M. G. and Friesen, Mark and Coppersmith, S. N. and Eriksson, M. A. (2013) Coherent quantum oscillations and echo measurements of a Si charge qubit. Physical review B, 88 (7): 075416. ISSN 1098-0121

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Fast quantum oscillations of a charge qubit in a double quantum dot fabricated in a Si/SiGe heterostructure are demonstrated and characterized experimentally. The measured inhomogeneous dephasing time T2* ranges from 127 ps to 2.1 ns; it depends substantially on how the energy difference of the two qubit states varies with external voltages, consistent with a decoherence process that is dominated by detuning noise (charge noise that changes the asymmetry of the qubit's double-well potential). In the regime with the shortest T2*, applying a charge-echo pulse sequence increases the measured inhomogeneous decoherence time from 127 to 760 ps, demonstrating that low-frequency noise processes are an important dephasing mechanism.

Item Type:
Journal Article
Journal or Publication Title:
Physical review B
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©2013 American Physical Society
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Deposited On:
14 Aug 2013 10:53
Last Modified:
31 Dec 2023 00:28