Abstract
We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the spontaneous qubit decay into a microwave transmission-line cavity can accurately predict the qubit lifetimes over 2 orders of magnitude in time and more than an octave in frequency. Coherence times and of more than a microsecond are reproducibly demonstrated.
- Received 31 March 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.080502
©2008 American Physical Society