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Measurement efficiency and n-shot read out of spin qubits

Hans-Andreas Engel·Vitaly Golovach·Daniel Loss·L. M. K. Vandersypen·J. M. Elzerman·R. Hanson·L. P. Kouwenhoven
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Abstract

We consider electron spin qubits in quantum dots and define a measurement efficiency e to characterize reliable measurements via n-shot read outs. We propose various implementations based on a double dot and quantum point contact (QPC) and show that the associated efficiencies e vary between 50% and 100%, allowing single-shot read out in the latter case. We model the read out microscopically and derive its time dynamics in terms of a generalized master equation, calculate the QPC current and show that it allows spin read out under realistic conditions.

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Hans-Andreas Engel, Vitaly Golovach, Daniel Loss, L. M. K. Vandersypen, J. M. Elzerman, R. Hanson, L. P. Kouwenhoven. 2003-09-01. Measurement efficiency and n-shot read out of spin qubits. https://doi.org/10.1103/physrevlett.93.106804

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