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arXiv · 1012.0007

Quantum state tomography of an itinerant squeezed microwave field

F. Mallet·M. A. Castellanos-Beltran·H. S. Ku·S. Glancy·E. Knill·K. D. Irwin·G. C. Hilton·L. R. Vale·K. W. Lehnert
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Abstract

We perform state tomography of an itinerant squeezed state of the microwave field prepared by a Josephson parametric amplifier (JPA). We use a second JPA as a pre-amplifier to improve the quantum efficiency of the field quadrature measurement (QM) from 2% to 36 +/- 4%. Without correcting for the detection inefficiency we observe a minimum quadrature variance which is 69 +/- 8% of the variance of the vacuum. We reconstruct the state's density matrix by a maximum likelihood method and infer that the squeezed state has a minimum variance less than 40% of the vacuum, with uncertainty mostly caused by calibration systematics.

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F. Mallet, M. A. Castellanos-Beltran, H. S. Ku, S. Glancy, E. Knill, K. D. Irwin, G. C. Hilton, L. R. Vale, K. W. Lehnert. 2011-05-06. Quantum state tomography of an itinerant squeezed microwave field. https://doi.org/10.1103/physrevlett.106.220502

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