Berlin 2015 – wissenschaftliches Programm
TT 21.46: Poster
Montag, 16. März 2015, 15:00–18:00, Poster B
Collective coupling of tunable transmon array via a cavity bus — •Ping Yang, Martin Weides, and Alexey V. Ustinov — Physikalisches Institut, KIT, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
Nowadays, superconducting multi-qubit circuits can be fabricated and studied experimentally. In order to manipulate the propagation of electromagnetic waves and explore the scalability of superconducting qubit circuits, we investigate coplanar waveguide resonators coupled to up to eight transmon qubits. An array of transmons can be viewed as a quantum metamaterial. Compared to a metamaterial made of flux qubits , our current approach using transmons anticipates smaller parameter spread and is easier to fabricate. The resonators are fabricated using optical lithography, while the qubits are made by using electron-beam lithography. Every qubit is biased individually via a flux-bias line. Thus, the interaction between the individual qubit and the resonator can be easily turned on and off by tuning the qubit eigenfrequencies. The simultaneous readout is implemented by measuring the dispersive shift of the resonator. This scheme enables one to study the collective behavior (Dicke state, quantum synchronization, superradiance) between all, or a subset of qubits.
 P. Macha, et al. Nature Commun. 5, 5146 (2014)