Microwave Down-Conversion with an Impedance-Matched A System in Driven Circuit QED

• Published in: Physical review letters Vol. 113; no. 6
• Main Authors: Inomata, K, Koshino, K, Lin, Z R, Oliver, W D, Tsai, J S, Nakamura, Y, Yamamoto, T
• Format: Journal Article
• Language: English
• Published: 08-08-2014
• Subjects: Circuits; Decay rate; Microwaves; Photons; Qubits (quantum computing); Reflection; Switches; Waveguides
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.113.063604

By driving a dispersively coupled qubit-resonator system, we realize an "impedance-matched" A system that has two identical radiative decay rates from the top level and interacts with a semi-infinite waveguide. It has been predicted that a photon input from the waveguide deterministically induces a Raman transition in the system and switches its electronic state. We confirm this through microwave response to a continuous probe field, observing near-perfect (99.7%) extinction of the reflection and highly efficient (74%) frequency down-conversion. These proof-of-principle results lead to deterministic quantum gates between material qubits and microwave photons and open the possibility for scalable quantum networks interconnected with waveguide photons.