The possibility is investigated that impurity spins in SQUID tunnel junctions might have a strong dissipative effect on macroscopic flux tunneling. A microscopic theory is given which shows that for temperatures lower than the Kondo temperature ${T}_{K}$ of the spins, there is a strong effect if ${T}_{K}\ensuremath{\simeq}{\ensuremath{\omega}}_{J}$, the Josephson plasma frequency. The connection with quantum measurement theory is discussed.The possibility is investigated that impurity spins in SQUID tunnel junctions might have a strong dissipative effect on macroscopic flux tunneling. A microscopic theory is given which shows that for temperatures lower than the Kondo temperature ${T}_{K}$ of the spins, there is a strong effect if ${T}_{K}\ensuremath{\simeq}{\ensuremath{\omega}}_{J}$, the Josephson plasma frequency. The connection with quantum measurement theory is discussed.

Physical Review LettersDec 26, 198814 citations

Resonant macroscopic quantum tunneling in small Josephson junctions: Effect of temperature

P. Silvestrini, B. Ruggiero, Yu. N. Ovchinnikov +1 more

Within the well-established quantum picture of Josephson junctions, we study the possibility of resonant macroscopic quantum tunneling. Expressions for the lifetime of metastable states are obtained and the effects of temperature on the main features of the phenomenon are discussed. A "saturation temperature" for the process, below which any temperature effect is negligible, is identified. Quantitative considerations are also given on the actual experimental accessibility to these measurements.Within the well-established quantum picture of Josephson junctions, we study the possibility of resonant macroscopic quantum tunneling. Expressions for the lifetime of metastable states are obtained and the effects of temperature on the main features of the phenomenon are discussed. A "saturation temperature" for the process, below which any temperature effect is negligible, is identified. Quantitative considerations are also given on the actual experimental accessibility to these measurements.

Physical review. B, Condensed matterJan 1, 199611 citations

{T}_{K}

of the spins, there is a strong effect if ${T}_{K}\ensuremath{\simeq}{\ensuremath{\omega}}_{J}$, the Josephson plasma frequency. The connection with quantum measurement theory is discussed.