Nonlinear microwave photon-occupancy of a driven resonator strongly coupled to a transmon qubit

Abstract

We measure photon-occupancy in a thin-film superconducting lumped element resonator coupled to a transmon qubit at 20mK and find a nonlinear dependence on the applied microwave power. The transmon-resonator system was operated in the strong dispersive regime, where the ac Stark shift ($2\chi$) due to a single microwave photon present in the resonator was larger than the linewidth ($\Gamma$) of the qubit transition. When the resonator was coherently driven at $5.474325$GHz, the transition spectrum of the transmon at $4.982$GHz revealed well-resolved peaks, each corresponding to an individual photon number-state of the resonator. From the relative peak-heights we obtain the occupancy of the photon-states and the average photon-occupancy $\bar{n}$ of the resonator. We observed a nonlinear variation of $\bar{n}$ with the applied drive power $P_{rf}$ for $\bar{n}<5$ and compare our results to numerical simulations of the system-bath master equation in the steady state, as well as to a semi-classical model for the resonator that includes the Jaynes-Cummings interaction between the transmon and the resonator. We find good quantitative agreement using both models and analysis reveals that the nonlinear behavior is principally due to shifts in the resonant frequency caused by a qubit-induced Jaynes-Cummings nonlinearity.

5 figures

References in corpus (11)

• Charge insensitive qubit design derived from the Cooper pair box
• Resolving photon number states in a superconducting circuit
• Generating Single Microwave Photons in a Circuit
• Qubit-photon interactions in a cavity: Measurement induced dephasing and number splitting
• Complete universal quantum gate set approaching fault-tolerant thresholds with superconducting qubits
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities
• Response of the Strongly-Driven Jaynes-Cummings Oscillator
• Sideband Transitions and Two-Tone Spectroscopy of a Superconducting Qubit Strongly Coupled to an On-Chip Cavity
• Autler-Townes splitting in a three-dimensional transmon superconducting qubit
• Observation of Autler-Townes effect in a dispersively dressed Jaynes-Cummings system

Cited by in corpus (10)

• Hybrid quantum systems based on magnonics
• Quantum Circuit Refrigerator
• Qubit-assisted transduction for a detection of surface acoustic waves near the quantum limit
• Nonclassical photon number distribution in a superconducting cavity under a squeezed drive
• Observation of the Bloch-Siegert shift in a driven quantum-to-classical transition
• Applications of the Fokker-Planck equation in circuit quantum electrodynamics
• Quantum interface between photonic and superconducting qubits
• Spectral response of a nonlinear Jaynes-Cummings model
• Supercomputer simulations of transmon quantum computers
• Characterising Polariton States in Non-Dispersive Regime of Circuit Quantum Electrodynamics