title: Measurement of the noise spectrum using a multiple-pulse sequence.
abstract: A method is proposed for obtaining the spectrum for noise that causes the phase decoherence of a qubit directly from experimentally available data. The method is based on a simple relationship between the spectrum and the coherence time of the qubit in the presence of a π pulse sequence. The relationship is found to hold for every system of a qubit interacting with the classical-noise, bosonic, and spin baths.
authors: IIAIR, Tohoku University, Sendai 980-8578, Japan. yuge@m.tohoku.ac.jp
authors: Tatsuro
authors: T
authors: Yuge
authors: Susumu
authors: S
authors: Sasaki
authors: Yoshiro
authors: Y
authors: Hirayama