Fluxonium: Single Cooper-Pair Circuit Free of Charge Offsets
Vladimir E. Manucharyan,
Jens Koch,
Leonid I. Glazman,
Michel H. Devoret*
The promise of single Cooper-pair quantum circuits based on
tunnel junctions for metrology and quantum information applications
is severely limited by the influence of offset charges: random,
slowly drifting microscopic charges inherent in many solid-state
systems. By shunting a small junction with the Josephson kinetic
inductance of a series array of large-capacitance tunnel junctions,
thereby ensuring that all superconducting islands are connected
to the circuit by at least one large junction, we have realized
a new superconducting artificial atom that is totally insensitive
to offset charges. Yet its energy levels manifest the anharmonic
structure associated with single Cooper-pair effects, a useful
component for solid-state quantum computation.
* To whom correspondence should be addressed. E-mail: michel.devoret{at}yale.edu
