Analysis of energy level quantization and tunneling from the zero-voltage state of a current-biased Josephson junction

We examine resonant activation from the zero-voltage state of a current-biased Josephson junction in the limit of low damping. In this limit, the quantum dynamics of a Josephson junction can be described by a master equation. Our finite temperature analysis includes transitions between any two levels in the potential well and accounts for escape near the top of the well. Our results show that energy level quantization in lightly damped junctions should be observable even for temperatures in the thermal regime, where only classical behavior is observed for junctions with moderate damping. Finally we discuss implications for ongoing experiments in quantum computation.