A scanning transmon qubit for strong coupling circuit quantum electrodynamics

摘要

Like a quantum computer designed for a particular class of problems, aquantum simulator enables quantitative modeling of quantum systems that iscomputationally intractable with a classical computer. Quantum simulations ofquantum many-body systems have been performed using ultracold atoms and trappedions among other systems. Superconducting circuits have recently beeninvestigated as an alternative system in which microwave photons confined to alattice of coupled resonators act as the particles under study with qubitscoupled to the resonators producing effective photon-photon interactions. Sucha system promises insight into the nonequilibrium physics of interacting bosonsbut new tools are needed to understand this complex behavior. Here wedemonstrate the operation of a scanning transmon qubit and propose its use as alocal probe of photon number within a superconducting resonator lattice. We mapthe coupling strength of the qubit to a resonator on a separate chip and showthat the system reaches the strong coupling regime over a wide scanning area.