Observation of final state effects on macroscopic quantum transitions

✍ Scribed by J. Lapointe; S. Han; J. Lukens

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 334 KB
• Volume: 165-166
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/s0921-4526(09)80061-6

✦ Synopsis

We have observed macroscopic quantum transitions in a symmetric double well potential (a SQUID with 'fl o /2 of external flux). The transition rate r ll( exp[-BliU/hwol has been measured vs. li U, the barrier height, for fixed temperature. This is achieved by modulating the barrier height in situ with the use of a tunable rf SQUID whose parameters have been accurately determined. The tunneling exponent obtained from these measurements, B = 10.3 ± 0.6, is in good agreement with the theoretical prediction. r has also been measured as a function of temperature (well below the crossover temperature to thermal activation) for fixed liU. A power law (Tl.8) dependence has been observed as predicted for incoherent relaxation in contrast to the exponential rate enhancement observed in previous tunneling measurements.