Slide 1

Metastability and self-oscillations in superconducting microwave Eran Segev Quantum Engineering Laboratory, Technion, Israel resonators integrated with a dc-SQUID Slide 2 Quantum Measurements of Solid-State Devices Indirect measurements approach: Resonance Readout - The quantum device is coupled to a superconducting resonator. Direct measurements of solid-state quantum devices has many drawbacks. V Input Probe Output Signal Freq Resonance Curve S12 Input Probe Output Signal Quantum Device The state of the device modifies the resonance frequencies. Readout is done by probing these resonance frequencies. Slide 3 Resonance readout and Thermal Instability 1m Feed line Resonator Weak link : Micro-Bridge Nonlinear thermal instability is expected under dc current bias. A. VI. Gurevich and R. G. Mints, Rev. Mod. Phys. 59, 941 (1987) Heat production: Heat balance condition: Heat transfer to a coolant hot spot Heat productionCooling power unstable Test bed for resonance readout Superconducting micro-bridge as artificial weak link. Slide 4 Self-Oscillations SC Threshold NC Threshold S.C Phase N.C Phase P res T Oscillation Cycle 1.Energy Buildup + Temperature increase 2.Switching the NC phase at T >= Tc 3.Energy relaxation + Temperature cool down 4.Switching back to the SC phase at T