Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent-Current Qubit

Yang Yu, William D. Oliver, J. C. Lee +3 more

Jonas Bylander, Simon Gustavsson, Fumiki Yoshihara +4 more

Yang Yu, D. Nakada, Janice C. Lee +5 more

We measured the intrawell energy relaxation time tau(d) approximately 24 micros between macroscopic quantum levels in the double well potential of a Nb persistent-current qubit. Interwell population transitions were generated by irradiating the qubit with microwaves. Zero population in the initial well was then observed due to a multilevel decay process in which the initial population relaxed to lower energy levels during the driven transitions. The decoherence time, estimated from tau(d) within the spin-boson model, is about 20 micros for this configuration with a Nb superconducting qubit.

Yang Yu, William D. Oliver, D. Nakada +3 more

We measured the energy relaxation time in a Nb superconducting persistent current qubit using a time-resolved fast measurement scheme. The energy relaxation time is longer than 10/spl mu/s, showing a strong potential of realizing quantum computation with Nb-based superconducting qubits.

Malcolm S. Carroll, Sami Rosenblatt, Abhinav Kandala

Lin Tian, Leonid S Levitov, Caspar H. van der Wal +5 more