We present an experimental realization of the transmon qubit, an improved superconducting charge qubit derived from the Cooper pair box. We experimentally verify the predicted exponential suppression of sensitivity to 1/f charge noise [J. Koch et al., Phys. Rev. A 76, 042319 (2007)]. This removes the leading source of dephasing in charge qubits, resulting in homogenously broadened transitions with relaxation and dephasing times in the microsecond range. Our systematic characterization of the qubit spectrum, anharmonicity, and charge dispersion shows excellent agreement with theory, rendering the transmon a promising qubit for future steps towards solid-state quantum information processing.
@article{arxiv.0712.3581,
title = {Suppressing Charge Noise Decoherence in Superconducting Charge Qubits},
author = {J. A. Schreier and A. A. Houck and Jens Koch and D. I. Schuster and B. R. Johnson and J. M. Chow and J. M. Gambetta and J. Majer and L. Frunzio and M. H. Devoret and S. M. Girvin and R. J. Schoelkopf},
journal= {arXiv preprint arXiv:0712.3581},
year = {2009}
}