title: Quantum nondemolition detection of a propagating microwave photon.
abstract: The ability to nondestructively detect the presence of a single, traveling photon has been a long-standing goal in optics, with applications in quantum information and measurement. Realizing such a detector is complicated by the fact that photon-photon interactions are typically very weak. At microwave frequencies, very strong effective photon-photon interactions in a waveguide have recently been demonstrated. Here we show how this type of interaction can be used to realize a quantum nondemolition measurement of a single propagating microwave photon. The scheme we propose uses a chain of solid-state three-level systems (transmons) cascaded through circulators which suppress photon backscattering. Our theoretical analysis shows that microwave-photon detection with fidelity around 90% can be realized with existing technologies.
authors.affiliation: Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
authors.forename: Sankar R
authors.initials: SR
authors.lastname: Sathyamoorthy
authors.affiliation: Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Tornberg
authors.affiliation: Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
authors.forename: Anton F
authors.initials: AF
authors.lastname: Kockum
authors.affiliation: Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
authors.forename: Ben Q
authors.initials: BQ
authors.lastname: Baragiola
authors.affiliation: Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Combes
authors.affiliation: Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden and Institute for Quantum Computing and Electrical and Computer Engineering Department, University of Waterloo, Waterloo N2 L 3G1, Canada.
authors.forename: C M
authors.initials: CM
authors.lastname: Wilson
authors.affiliation: Centre for Engineered Quantum Systems, School of Physical Sciences, University of Queensland, Saint Lucia, Queensland 4072, Australia.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Stace
authors.affiliation: Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Johansson