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Dispersive Charge and Flux Qubit Readout as a Quantum Measurement Process

Lars Tornberg (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik) ; Göran Johansson (Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik)
Journal of Low Temperature Physics (0022-2291). Vol. 146 (2007), 1-2, p. 227-252.
[Artikel, refereegranskad vetenskaplig]

We analyze the dispersive readout of superconducting charge and flux qubits as a quantum measurement process. The measurement oscillator frequency is considered much lower than the qubit frequency. This regime is interesting because large detuning allows for strong coupling between the measurement oscillator and the signal transmission line, thus allowing for fast readout. Due to the large detuning we may not use the rotating wave approximation in the oscillator-qubit coupling. Instead we start from an approximation where the qubit follows the oscillator adiabatically, and show that non-adiabatic corrections are small. We find analytic expressions for the measurement time, as well as for the back-action, both while measuring and in the off-state. The quantum efficiency is found to be unity within our approximation, both for charge and flux qubit readout.

Nyckelord: quantum computing - quantum measurements - superconducting qubits - quantum electrical circuits - single Cooper-pair box



Denna post skapades 2008-01-25. Senast ändrad 2014-09-02.
CPL Pubid: 67795

 

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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Tillämpad kvantfysik

Ämnesområden

Supraledning
Mesoskopisk fysik

Chalmers infrastruktur

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