Reversing quantum trajectories with analog feedback

G. De Lange, D. Ristè, M. J. Tiggelman, C. Eichler, L. Tornberg, G. Johansson, A. Wallraff, R. N. Schouten, L. Dicarlo

Research output: Contribution to journalArticlepeer-review


We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model of quantum trajectories with a measurement efficiency ηËœ≈0.5, consistent with the result obtained by postselection. We overcome the bandwidth limitations of the amplification chain by numerically optimizing the signal processing in the feedback loop and provide a theoretical model explaining the optimization result.

Original languageEnglish
Article number080501
JournalPhysical Review Letters
Issue number8
StatePublished - 24 Feb 2014
Externally publishedYes


Dive into the research topics of 'Reversing quantum trajectories with analog feedback'. Together they form a unique fingerprint.

Cite this