Coherent state evolution in a superconducting qubit from partial-collapse measurement

N. Katz, M. Ansmann, Radoslaw C. Bialczak, Erik Lucero, R. McDermott, Matthew Neeley, Matthias Steffen, E. M. Weig, A. N. Cleland, John M. Martinis*, A. N. Korotkov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

143 Scopus citations


Measurement is one of the fundamental building blocks of quantum-information processing systems. Partial measurement, where full wavefunction collapse is not the only outcome, provides a detailed test of the measurement process. We introduce quantum-state tomography in a superconducting qubit that exhibits high-fidelity single-shot measurement For the two probabilistic outcomes of partial measurement we find either a full collapse or a coherent yet nonunitary evolution of the state. This latter behavior explicitly confirms modern quantum-measurement theory and may prove important for error-correction algorithms in quantum computation.

Original languageAmerican English
Pages (from-to)1498-1500
Number of pages3
Issue number5779
StatePublished - 9 Jun 2006
Externally publishedYes


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