Coherent control of macroscopic quantum states in a single-Cooper-pair box

摘要: A small superconducting electrode (a single-Cooper-pair box) connected to a reservoir via Josephson junction constitutes an artificial two-level system, in which two charge states that differ by 2e are coupled tunneling of Cooper pairs. Despite its macroscopic nature involving large number electrons, the system shows coherent superposition states, and has been suggested as candidate for qubit, i.e. basic component quantum computer. Here we report on time-domain observation quantum-state evolution applying short voltage pulse modifies energies levels nonadiabatically control evolution. The resulting state was probed current through additional probe junction. Our results demonstrate operation measurement single solid-state electronic device.