Phys. Rev. Lett. 93, 106804 (2004) [4 pages]Measurement Efficiency and n-Shot Readout of Spin QubitsReceived 1 September 2003; published 3 September 2004 We consider electron spin qubits in quantum dots and define a measurement efficiency e to characterize reliable measurements via n-shot readouts. We propose various implementations based on a double dot and a quantum point contact (QPC) and show that the associated efficiencies e vary between 50% and 100%, allowing single-shot readout in the latter case. We model the readout microscopically and derive its time dynamics in terms of a generalized master equation, calculate the QPC current, and show that it allows spin readout under realistic conditions. © 2004 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.93.106804
DOI:
10.1103/PhysRevLett.93.106804
PACS:
73.63.Kv, 03.65.Ta, 72.25.–b, 85.35.–p
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