Title: "Analog simulations of quantum impurity physics with a high-impedance Josephson transmission line"
Abstract: Interacting 1D electrons are usually understood within the Luttinger liquid picture as acoustic charge-density waves, analogous to TEM photons in a telegraph transmission line. This system is known to exhibit non-perturbative many-body dynamics upon introducing a single back-scattering impurity. The rich phenomenology of such a system, similar to the Kondo problem, is usually referred to as quantum impurity physics. Interestingly, a back-scattering impurity is mathematically equivalent to a Josephson junction embedded into a transmission line. The critical behavior (Luttinger parameter of order unity) occurs when the impedance of the transmission line is crossing the value of the resistance quantum for Cooper pairs. One can thus probe quantum impurity physics in a simple microwave scattering experiment. In this talk, we present our implementation of a quantum impurity simulator by introducing a small "impurity" Josephson junction into a high-impedance transmission line. To boost the wave impedance to the value above resistance quantum, our transmission line is fabricated out of a Josephson junction chain containing over 50,000 optimal size junctions.