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

Max Haeberlein, Frank Deppe, Andreas Kurcz, Jan Goetz, Alexander Baust, Peter Eder, Kirill Fedorov, Michael Fischer, Edwin P. Menzel, Manuel J. Schwarz, Friedrich Wulschner, Edwar Xie, Ling Zhong, Enrique Solano, Achim Marx, Juan-José García-Ripoll, Rudolf Gross

Published 2015-06-30Version 1

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. Our work lays the ground for future quantum simulations of other, more involved, impurity models with superconducting circuits.