title: Synchronized switching in a josephson junction crystal.
abstract: We consider a superconducting coplanar waveguide resonator where the central conductor is interrupted by a series of uniformly spaced Josephson junctions. The device forms an extended medium that is optically nonlinear on the single photon level with normal modes that inherit the full nonlinearity of the junctions but are nonetheless accessible via the resonator ports. For specific plasma frequencies of the junctions, a set of normal modes clusters in a narrow band and eventually becomes entirely degenerate. Upon increasing the intensity of a red detuned drive on these modes, we observe a sharp and synchronized switching from low-occupation quantum states to high-occupation classical fields, accompanied by a pronounced jump from low to high output intensity.
authors.affiliation: Technische Universität München, Physik Department, James Franck Straße, 85748 Garching, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Leib
authors.affiliation: Technische Universität München, Physik Department, James Franck Straße, 85748 Garching, Germany and Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hartmann