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

Yang Yu; D. Nakada; Janice C. Lee; Bhuwan Singh; D. S. Crankshaw; T. P. Orlando; Karl K. Berggren; William D. Oliver

doi:10.1103/PhysRevLett.92.117904

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

Yang Yu, D. Nakada, Janice C. Lee, Bhuwan Singh, D. S. Crankshaw, T. P. Orlando, Karl K. Berggren, William D. Oliver

DOI 10.1103/PhysRevLett.92.117904 · Physical Review Letters

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Abstract

We measured the intrawell energy relaxation time τd≃24 μs 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 τd within the spin-boson model, is about 20 μs for this configuration with a Nb superconducting qubit.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
NbN Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown