title: A scanning transmon qubit for strong coupling circuit quantum electrodynamics.
abstract: Like a quantum computer designed for a particular class of problems, a quantum simulator enables quantitative modelling of quantum systems that is computationally intractable with a classical computer. Superconducting circuits have recently been investigated as an alternative system in which microwave photons confined to a lattice of coupled resonators act as the particles under study, with qubits coupled to the resonators producing effective photon-photon interactions. Such a system promises insight into the non-equilibrium physics of interacting bosons, but new tools are needed to understand this complex behaviour. Here we demonstrate the operation of a scanning transmon qubit and propose its use as a local probe of photon number within a superconducting resonator lattice. We map the coupling strength of the qubit to a resonator on a separate chip and show that the system reaches the strong coupling regime over a wide scanning area.
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton 08550, New Jersey, USA.
authors.forename: W E
authors.initials: WE
authors.lastname: Shanks
authors.forename: D L
authors.initials: DL
authors.lastname: Underwood
authors.forename: A A
authors.initials: AA
authors.lastname: Houck