Alexey Ustinov

Karlsruhe Institute of Technology, Germany

6 April 2023 Thu 4 pm

                                      IBS Center for Theoretical Physics of Complex Systems (PCS), Administrative Office (B349), Theory Wing, 3rd floor

                                      Expo-ro 55, Yuseong-gu, Daejeon, South Korea, 34126 Tel: +82-42-878-8633                     

Progress in quantum information processing leads to a rising demand for devices to control the propagation of electromagnetic wave pulses and to ultimately realize a universal and efficient quantum memory. While in recent years significant progress has been made to realize slow light and quantum memories with atoms at optical frequencies, superconducting circuits in the microwave domain still lack such devices. I will present an overview of our recent experiments with arrays of eight frequency-tunable transmon qubits coupled to a one-dimensional waveguide. By consecutively bringing the qubits to a common resonance frequency we observe the formation of super- and subradiant states, as well as the emergence of a bandgap. We also experimentally demonstrate slowing down electromagnetic waves in this qubit array. Time-resolved experiments show electromagnetic wave group velocities reduced by a factor of about 1500 in the single-photon regime. Our findings demonstrate high flexibility of superconducting circuits to realize custom band structures and open the door to microwave dispersion engineering in the quantum regime.

  1. slowing down microwave photons with superconducting qubits