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Coherence of an Electronic Two-Level System under Continuous Charge Sensing by a Quantum Dot Detector
Subhomoy Haldar1, Morten Munk2, Harald Havir1
1Lund University, NanoLund and Solid State Physics, Box 118, 22100 Lund, Sweden.
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.
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