Qdev Seminar by Jeffrey Grover
Title: Waveguide QED Experiments with Real and Artificial Atoms
Abstract: The strong-coupling regime of atom-photon interactions, where a single atom and single photon can coherently exchange an excitation, is a common target for quantum optics and quantum information platforms. This is now readily achieved in cavity Quantum Electrodynamics (QED), where real or artificial atoms are confined in the modes of cavities. There is a complementary paradigm, dubbed waveguide QED, where instead atoms couple to itinerant photons propagating in waveguides. The small mode volume of the waveguide can enable the strong-coupling regime even without cavity enhancement. In this talk, we discuss waveguide QED experiments in two architectures: real atoms coupled to optical nanofibers, and superconducting artificial atoms coupled to microwave coplanar waveguides. In particular we show how we can control the spontaneous emission rate of atoms around a nanofiber. Then, by moving to superconducting qubits, we substantially increase the atom-photon coupling, allowing us to deterministically emit a photon into a chosen direction. This scheme is a potential building block for remote entanglement or quantum communication protocols.