Bi2Sr2CaCu2O8+δ intrinsic SQUIDs as candidates of high-Tc phase qubits

An intrinsic SQUID is a superconducting ring made of Bi2Sr2CaCu2O8+δ single crystal, intercepted by two intrinsic Josephson junction stacks. When biased with dc current, the device is a typical hysteretic dc-SQUIDs with huge inductance. The inductance parameter βL can be tuned in a wide range between 4 and 30 by changing the height and the cross-section area of the stacks. When a device was coupled with a coil and a Nb readout dc-SQUID, typical rf-SQUID behavior was observed. By applying a proper reset field, quantum escape from a single minimum has been measured on a sample of βL∝10. The escape rate can be fine-tuned by applying short pulses down to 1 ns, which allows a fast readout technique. With these prerequisites, our experiments have opened the path to directly using these intrinsic SQUIDs as high-Tc phase qubits. The first attempts to measure Rabi oscillations on these devices are discussed.