Photon-number-dependent effective Lamb shift

Abstract

The Lamb shift, an energy shift arising from the presence of the electromagnetic vacuum, has been observed in various quantum systems and established as the part of the energy shift independent of the environmental photon number. However, typical studies are based on simplistic bosonic models which may be challenged in practical quantum devices. We demonstrate a hybrid bosonic-fermionic environment for a linear resonator mode and observe that the photon number in the environment can dramatically increase both the dissipation and the effective Lamb shift of the mode. Our observations are quantitatively described by a first-principles model which we develop here also to guide device design for future quantum-technological applications. The device demonstrated here can be utilized as a fully rf-operated quantum-circuit refrigerator to quickly reset superconducting qubits.

15 pages, 10 figures

References in corpus (4)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Quantum Computing
• Theory of quantum-circuit refrigeration by photon-assisted electron tunneling
• Calibration of cryogenic amplification chains using normal-metal--insulator--superconductor junctions

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• Assessment of weak-coupling approximations on a driven two-level system under dissipation
• Charge dynamics in quantum-circuit refrigeration: thermalization and microwave gain
• Exceptional-point-assisted entanglement, squeezing, and reset in a chain of three superconducting resonators
• Quantum-circuit refrigeration of a superconducting microwave resonator well below a single quantum
• Many-excitation removal of a transmon qubit using a single-junction quantum-circuit refrigerator and a two-tone microwave drive
• Rapid on-demand generation of thermal states in superconducting quantum circuits
• Dissipation and noise in strongly driven Josephson junctions