@article{TEXTUAL,
      recid = {11424},
      author = {Eddins, A. and Kreikebaum, J. M. and Toyli, D. M. and  Levenson-Falk, E. M. and Dove, A. and Livingston, W. P. and  Levitan, B. A. and Govia, L. C. G. and Clerk, A. A. and  Siddiqi, I.},
      title = {High-Efficiency Measurement of an Artificial Atom Embedded  in a Parametric Amplifier},
      journal = {Physical Review X},
      address = {2019-01-07},
      number = {TEXTUAL},
      abstract = {A crucial limit to measurement efficiencies of  superconducting circuits comes from losses involved when  coupling to an external quantum amplifier. Here, we realize  a device circumventing this problem by directly embedding  an artificial atom, comprised of a transmon qubit, within a  flux-pumped Josephson parametric amplifier. This  configuration is able to enhance dispersive measurement  without exposing the qubit to appreciable excess  backaction. Near-optimal backaction is obtained by  engineering the circuit to permit high-power operation that  reduces information loss to unmonitored channels associated  with the amplification and squeezing of quantum noise. By  mitigating the effects of off-chip losses downstream, the  on-chip gain of this device produces end-to-end measurement  efficiencies of up to 80%. Our theoretical model accurately  describes the observed interplay of gain and measurement  backaction and delineates the parameter space for future  improvement. The device is compatible with standard  fabrication and measurement techniques and, thus, provides  a route for definitive investigations of fundamental  quantum effects and quantum control protocols.},
      url = {http://knowledge.uchicago.edu/record/11424},
}