Tunable ohmic environment using Josephson junction chains

Year: 2018

Authors: Rastelli G., Pop I.M.

Autors Affiliation: Univ Konstanz, Zukunftskolleg & Fachbereich Phys, D-78457 Constance, Germany. Karlsruhe Inst Technol, Phys Inst, D-76131 Karlsruhe, Germany

Abstract: We propose a scheme to implement a tunable, wide frequency-band dissipative environment using a double chain of Josephson junctions. The two parallel chains consist of identical superconducting quantum interference devices (SQUIDs), with magnetic-flux tunable inductance, coupled to each other at each node via a capacitance much larger than the junction capacitance. Thanks to this capacitive coupling, the system sustains electromagnetic modes with a wide frequency dispersion. The internal quality factor of the modes is maintained as high as possible, and the damping is introduced by a uniform coupling of the modes to a transmission line, itself connected to an amplification and readout circuit. For sufficiently long chains, containing several thousands of junctions, the resulting admittance is a smooth function versus frequency in the microwave domain, and its effective dissipation can be continuously monitored by recording the emitted radiation in the transmission line. We show that by varying in situ the SQUIDs´ inductance, the double chain can operate as a tunable ohmic resistor in a frequency band spanning up to 1 GHz, with a resistance that can be swept through values comparable to the resistance quantum R-q = h/(4e(2)) similar or equal to 6.5 k Omega. We argue that the circuit complexity is within reach using current Josephson junction technology.

Journal/Review: PHYSICAL REVIEW B

Volume: 97 (20)      Pages from: 205429  to: 205429

More Information: We acknowledge Denis Basko for interesting discussions and useful comments. G.R. acknowledges support from by the German Excellence Initiative through the Zukunftskolleg of the University of Konstanz, the DFG through the SFB 767 and Grant No. 13971016, and the MWK-RiSC program, Project No. 13551400. I.M.P. acknowledges support from the Alexander von Humboldt Foundation in the framework of a Sofja Kovalevskaja award endowed by the German Federal Ministry of Education and Research.
KeyWords: quantum microwave circuits, Josephson junction systems
DOI: 10.1103/PhysRevB.97.205429