Qubit state tomography in superconducting circuit via weak measurements

Abstract

The standard method of "measuring" quantum wavefunction is the technique of {\it indirect} quantum state tomography. Owing to conceptual novelty and possible advantages, an alternative {\it direct} scheme was proposed and demonstrated recently in quantum optics system. In this work we present a study on the direct scheme of measuring qubit state in the circuit QED system, based on weak measurement and weak value concepts. To be applied to generic parameter conditions, our formulation and analysis are carried out for finite strength weak measurement, and in particular beyond the bad-cavity and weak-response limits. The proposed study is accessible to the present state-of-the-art circuit-QED experiments.

7 pages,5figures

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• Overcoming experimental limitations in a non-linear two-qubit gate through postselection
• Increase the Efficiency of Post-selection in Direct Measurement of Quantum Wave Function
• Gradual partial-collapse theory for ideal nondemolition measurements of qubits in circuit QED
• Weak-valued correlation functions: Insights and precise readout strategies
• Superoscillating Quantum Control Induced By Sequential Selections