Quantum phenomena in mesoscopic superconducting tunnel junctions

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1988

OSTI ID:7256924

Iansiti, M

A low-temperature study of very small superconducting tunnel junctions is reported. The junctions had normal resistances between 0.5 and 140 k{Omega} and areas between 0.1 and 0.2 ({mu}m){sup 2}. The current-voltage characteristics of the devices were measured at low temperatures (20 mK-4 K), using a dilution refrigerator. In general, the devices had a large single-electron charging energy E{sub c} {triple bond} e{sup 2}/2C of order 1 K. By varying the ratio of E{sub c} to the Josephson coupling energy E{sub J}, the crossover was studied between the conventional Josephson regime, in which E{sub J} >> E{sub c}, and the Coulomb blockade regime, in which charging effects are dominant. A number of semiquantitative models were developed that appear to explain the salient new features of the observations. In the high-temperature regime, thermal activation and damping effects are very important, since E{sub c} and E{sub J} are only of order 1 K, and the experimental results are fitted by extending well established classical models. At low temperatures, however, quantum fluctuations of the phase appear to become much more important, as thermal fluctuations and quasi-particle damping freeze out. Quantum-mechanical methods are used to analyzed the measurements.

• Research Organization: Harvard Univ., Boston, MA (USA)
• OSTI ID: 7256924
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
SUPERCONDUCTING JUNCTIONS
ELECTRIC CONDUCTIVITY
DAMPING
ELECTRIC CHARGES
JOSEPHSON EFFECT
MATHEMATICAL MODELS
QUANTUM MECHANICS
TUNNEL EFFECT
ULTRALOW TEMPERATURE
ELECTRICAL PROPERTIES
JUNCTIONS
MECHANICS
PHYSICAL PROPERTIES
426001* - Engineering- Superconducting Devices & Circuits- (1990-)