By driving a dispersively coupled qubit-resonator system, we realize an "impedance-matched" Λ 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.
@article{arxiv.1405.5592,
title = {Microwave Down-Conversion with an Impedance-Matched $\Lambda$ System in Driven Circuit QED},
author = {K. Inomata and K. Koshino and Z. R. Lin and W. D. Oliver and J. S. Tsai and Y. Nakamura and T. Yamamoto},
journal= {arXiv preprint arXiv:1405.5592},
year = {2014}
}