title: Quantum noise in the josephson charge qubit.
abstract: We study decoherence of the Josephson charge qubit by measuring energy relaxation and dephasing with help of the single-shot readout. We found that the dominant energy relaxation process is a spontaneous emission induced by quantum noise coupled to the charge degree of freedom. Spectral density of the noise at high frequencies is roughly proportional to the qubit excitation energy.
authors.affiliation: The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan. astf@frl.cl.nec.co.jp
authors.forename: O
authors.initials: O
authors.lastname: Astafiev
authors.forename: Yu A
authors.initials: YA
authors.lastname: Pashkin
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: J S
authors.initials: JS
authors.lastname: Tsai