Spin-boson model with an engineered reservoir in circuit quantum electrodynamics

Understand

A superconducting qubit coupled to an open transmission line represents an implementation of the spin-boson model with a broadband environment.

• We show that this environment can be engineered by introducing partial reflectors into the transmission line, allowing to shape the spectral function, J({\omega}), of the spin-boson model.
• The spectral function can be accessed by measuring the resonance fluorescence of the qubit, which provides information on both the engineered environment and the coupling between qubit and transmission line.
• The spectral function of a transmission line without partial reflectors is found to be Ohmic over a wide frequency range, whereas a peaked spectral density is found for the shaped environment.