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Undoing measurement-induced dephasing in circuit QED

Anton Frisk Kockum (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik) ; Lars Tornberg (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik) ; Göran Johansson (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik)
Physical Review A (1050-2947). Vol. 85 (2012), 5,
[Artikel, refereegranskad vetenskaplig]

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 on an earlier one [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.

Nyckelord: quantum, entanglement, qubits



Denna post skapades 2012-07-02. Senast ändrad 2014-09-02.
CPL Pubid: 159882

 

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Projekt

Denna publikation är ett resultat av följande projekt:


Solid state systems for quantum information processing (SOLID) (EC/FP7/248629)