A. Frisk Kockum, L. Tornberg, G. Johansson
We analyze the backaction of homodyne detection and photodetection on
superconducting qubits in circuit quantum electrodynamics. Although both
measurement schemes give rise to backaction in the form of stochastic phase
rotations, which leads to dephasing, we show that this can be perfectly undone
provided that the measurement signal is fully accounted for. This result
improves upon that of Phys. Rev. A, 82, 012329 (2010), showing that the method
suggested can be made to realize a perfect two-qubit parity measurement. We
propose a benchmarking experiment on a single qubit to demonstrate the method
using homodyne detection. By analyzing the limited measurement efficiency of
the detector and bandwidth of the amplifier, we show that the parameter values
necessary to see the effect are within the limits of existing technology.
View original:
http://arxiv.org/abs/1202.2386
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