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arXiv:2406.11383 · Physical Review Letters

Coherence of an Electronic Two-Level System under Continuous Charge Sensing by a Quantum Dot Detector

Subhomoy Haldar, Morten I. K. Munk, Harald Havir, Waqar Hussain Khan, Sebastian Lehmann, Claes Thelander, Kimberly A. Dick, Peter Samuelsson, Patrick P. Potts, V. F. Maisi

Published Jan 15, 2025• 5 citations
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Abstract

We investigate experimentally the quantum coherence of an electronic two-level system in a double quantum dot under continuous charge detection. The charge state of the two-level system is monitored by a capacitively coupled single quantum dot detector that imposes a backaction effect on the system. The measured backaction is well described by an additional decoherence rate, approximately linearly proportional to the detector electron tunneling rate. We provide a model for the decoherence rate arising due to level detuning fluctuations induced by detector charge fluctuations. The theory predicts a factor of 2 lower decoherence rates than observed in the experiment, suggesting the need for a more elaborate theory accounting for additional sources of decoherence.

DOI
10.1103/physrevlett.134.023601

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We investigate experimentally the quantum coherence of an electronic two-level system in a double quantum dot under continuous charge detection. The charge state of the two-level system is monitored by a capacitively coupled single quantum dot detector that imposes a backaction effect on the system. The measured backaction is well described by an additional decoherence rate, approximately linearly proportional to the detector electron tunneling rate. We provide a model for the decoherence rate arising due to level detuning fluctuations induced by detector charge fluctuations. The theory predicts a factor of 2 lower decoherence rates than observed in the experiment, suggesting the need for a more elaborate theory accounting for additional sources of decoherence.
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