Quantum state tomography of an itinerant squeezed microwave field

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 preamplifier to improve the quantum efficiency of the field quadrature measurement from 2% to 36%±4%. Without correcting for the detection in...

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Veröffentlicht in:Physical review letters 2011-06, Vol.106 (22), p.220502-220502, Article 220502
Hauptverfasser: Mallet, F, Castellanos-Beltran, M A, Ku, H S, Glancy, S, Knill, E, Irwin, K D, Hilton, G C, Vale, L R, Lehnert, K W
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Sprache:eng
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Zusammenfassung: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 preamplifier to improve the quantum efficiency of the field quadrature measurement from 2% to 36%±4%. Without correcting for the detection inefficiency we observe a minimum quadrature variance which is 68(-7)(+9)% 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.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.106.220502