title: Breakdown of the cross-Kerr scheme for photon counting.
abstract: 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.
authors: Center for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia.
authors: Bixuan
authors: B
authors: Fan
authors: Anton F
authors: AF
authors: Kockum
authors: Joshua
authors: J
authors: Combes
authors: Göran
authors: G
authors: Johansson
authors: Io-chun
authors: IC
authors: Hoi
authors: C M
authors: CM
authors: Wilson
authors: Per
authors: P
authors: Delsing
authors: G J
authors: GJ
authors: Milburn
authors: Thomas M
authors: TM
authors: Stace