Typically, excited atoms in open environments will exhibit dissipative and irreversible dynamics through the spontaneous emission of photons. However, by precisely positioning artificial atoms in the form of superconducting transmon qubits along a one-dimensional waveguide, we experimentally observed that the same photons that typically give rise to dissipation can also produce strong, coherent dynamics. This phenomenon is produced due to dynamical exchange between a single artificial atom and an emergent entangled state of the array. The ability to coax coherent dynamics from such a nominally dissipative system provides a route toward diverse applications like the generation of exotic quantum many-body states of light, quantum computing in decoherence-free subspaces, and multi-photon quantum state synthesis.
Reference
Mirhosseini M, Kim E, Zhang X, Sipahigil A, Dieterle PB, Keller AJ, Asenjo-Garcia A, Chang DE & Painter O 2019, ‘Cavity quantum electrodynamics with atom-like mirrors’, Nature, 569, 7758, 692.
Scanning electron microscope image of a superconducting transmon qubit5tgb7UJM coupled to a microwave waveguide. Strong coherent coupling between up to seven qubits mediated by the waveguide is observed in the experiment.