Measurement-induced qubit state mixing in circuit QED from up-converted dephasing noise

Abstract

We observe measurement-induced qubit state mixing in a transmon qubit dispersively coupled to a planar readout cavity. Our results indicate that dephasing noise at the qubit-readout detuning frequency is up-converted by readout photons to cause spurious qubit state transitions, thus limiting the nondemolition character of the readout. Furthermore, we use the qubit transition rate as a tool to extract an equivalent flux noise spectral density at f ~ 1 GHz and find agreement with values extrapolated from a $1/f^{\alpha }$ fit to the measured flux noise spectral density below 1 Hz.

5 pages, 4 figures. Final journal version

References in corpus (19)

• Charge insensitive qubit design derived from the Cooper pair box
• Dynamical decoupling and noise spectroscopy with a superconducting flux qubit
• Approaching Unit Visibility for Control of a Superconducting Qubit with Dispersive Readout
• AC-Stark Shift and Dephasing of a Superconducting Qubit Strongly Coupled to a Cavity Field
• Decoherence of flux qubits due to 1/f flux noise
• Observation of quantum jumps in a superconducting artificial atom
• Dispersive regime of circuit QED: photon-dependent qubit dephasing and relaxation rates
• Single-shot qubit readout in circuit Quantum Electrodynamics
• Single-shot qubit readout in circuit Quantum Electrodynamics
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Model for l/f Flux Noise in SQUIDs and Qubits
• 1/f Flux Noise in Josephson Phase Qubits
• Initialization by measurement of a two-qubit superconducting circuit
• A semi-empirical model for two-level system noise in superconducting microresonators
• Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities
• Response of the Strongly-Driven Jaynes-Cummings Oscillator
• Improving the Quality Factor of Microwave Compact Resonators by Optimizing their Geometrical Parameters
• Millikelvin thermal and electrical performance of lossy transmission line filters
• Nonlinear microwave response of aluminum weak-link Josephson oscillators

Cited by in corpus (1)

• Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations