Spectroscopy of a Cooper-pair box in the Autler-Townes configuration

We propose techniques for implementing two different rapid-state purification schemes, within the constraints present in a superconducting charge qubit system. Both schemes use a continuous measurement of charge ͑z͒ measurements and seek to minimize the time required to purify the conditional state. Our methods are designed to make the purification process relatively insensitive to rotations about the x-axis, due to the Josephson tunneling Hamiltonian. The first proposed method, based on the scheme of Jacobs ͓Phys. Rev. A 67, 030301͑R͒ ͑2003͔͒ uses the measurement results to control bias ͑z͒ pulses so as to rotate the Bloch vector onto the x-axis of the Bloch sphere. The second proposed method, based on the scheme of Wiseman and Ralph ͓New J. Phys. 8, 90 ͑2006͔͒ uses a simple feedback protocol which tightly rotates the Bloch vector about an axis almost parallel with the measurement axis. We compare the performance of these and other techniques by a number of different measures.

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“…For simplicity, we ignore the dynamics of the biasing circuitry. 13 The Hamiltonian of this system is…”

Section: System Modelmentioning

confidence: 99%

“…The island is also capacitively coupled to a grounded electrode to supply a common reference. For simplicity, we ignore the dynamics of the biasing circuitry [13].…”

Section: System Modelmentioning

confidence: 99%

Rapid-state purification protocols for a Cooper pair box

et al. 2007

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“…On the other hand, system measurements can be performed on both subsystems, but probing the oscillator is preferred as it is easily accessible via weak measurements [27]. The present study aims at the dynamics of the boson field in the regime g < v ω and beyond the rotating-wave approximation (RWA).…”

Section: Introductionmentioning

confidence: 99%

“…Although the dynamics of the two-level subsystem have been studied at length in the regime v, g < ω, less attention has been paid to the dynamics of the quantum oscillator subsystem. On the other hand, system measurements can be performed on both subsystems, but probing the oscillator is preferred as it is easily accessible via weak measurements [27]. The present study aims at the dynamics of the boson field in the regime g < v ≪ ω and beyond the rotating-wave approximation (RWA).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a quantum oscillator strongly and off-resonantly coupled with a two-level system

Sandu

2009

Physics Letters A

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Beyond the rotating-wave approximation, the dynamics of a quantum oscillator interacting strongly and off-resonantly with a two-level system exhibit beatings, whose period equals the revival time of the two-level system. On a longer time scale, the quantum oscillator shows collapses, revivals and fractional revivals, which are encountered in oscillator observables like the mean number of oscillator quanta and in the two-level inversion population. Also the scattered oscillator field shows doublets with symmetrically displaced peaks.

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