Speaker
Description
Advances in circuit quantum electrodynamics (cQED) provide new ways to look at well-known condensed matter problems. I will present our results on the quantum phase transition between superconducting and insulating states of a single Josephson junction placed in an ohmic dissipative environment [1]. Employing the tools of cQED, we gain access to individual degrees of freedom of the dissipative environment, which we construct as a long section of a high-impedance transmission line. Such a setup allows us to study how a small Josephson junction scatters environmental photons as we tune the strength of the dissipation. The photon scattering rates and their scaling provide an unambiguous way to separate superconducting and insulating junction’s behavior, revealing the transition, observation of which has been a challenge. I will also briefly discuss other applications of high-impedance circuits for the simulation of quantum many-body physics.
[1] R. Kuzmin, N. Mehta, N. Grabon, R. A. Mencia, A. Burshtein, M. Goldstein, V. E. Manucharyan. Observation of the Schmid-Bulgadaev dissipative quantum phase transition. Nature Physics 21, 132-136 (2025).
