1/f Flux noise in Josephson phase qubits

Radoslaw C. Bialczak*, R. McDermott, M. Ansmann, M. Hofheinz, N. Katz, Erik Lucero, Matthew Neeley, A. D. O'Connell, H. Wang, A. N. Cleland, John M. Martinis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

162 Scopus citations


We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1 Hz. A comparison of the noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux noise and not junction critical-current noise, with a magnitude similar to that measured previously in other systems. Theoretical calculations show that the level of flux noise is not compatible with the standard model of noise from two-level state defects in the surface oxides of the films.

Original languageAmerican English
Article number187006
JournalPhysical Review Letters
Issue number18
StatePublished - 2 Nov 2007
Externally publishedYes


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