Breakdown of the cross-kerr scheme for photon counting

Bixuan Fan*, Anton F. Kockum, Joshua Combes, Göran Johansson, Io Chun Hoi, C. M. Wilson, Per Delsing, G. J. Milburn, Thomas M. Stace

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We show, in the context of single-photon detection, that an atomic three-level model for a transmon in a transmission line does not support the predictions of the nonlinear polarizability model known as the cross-Kerr effect. We show that the induced displacement of a probe in the presence or absence of a single photon in the signal field, cannot be resolved above the quantum noise in the probe. This strongly suggests that cross-Kerr media are not suitable for photon counting or related single-photon applications. Our results are presented in the context of a transmon in a one-dimensional microwave waveguide, but the conclusions also apply to optical systems.

Original languageEnglish
Article number053601
JournalPhysical Review Letters
Issue number5
StatePublished - 30 Jan 2013
Externally publishedYes


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