Observation of parametric amplification and deamplification in a Josephson parametric amplifier
- 1 March 1989
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review A
- Vol. 39 (5), 2519-2533
- https://doi.org/10.1103/physreva.39.2519
Abstract
We present the results of an experimental effort to generate squeezed microwave radiation using the phase-sensitive gain of a Josephson parametric amplifier. To facilitate the interpretation of the experimental results, we first present a discussion of the theory of microwave squeezing via Josephson parametric amplifiers. This is followed by a detailed description of the device fabricated for our experiment. Experimental results are then presented for the device used in both the doubly degenerate or four-photon mode and for the degenerate or three-photon mode. We have observed parametric deamplification of signals by more than 8 dB. We have demonstrated squeezing of 4.2-K thermal noise. When operated at 0.1 K, the amplifier exhibits an excess noise of 0.28 K when referred to the input. This is smaller than the vacuum fluctuation noise level ħω/2k=0.47 K. The amplifier is thus quieter than a linear phase-insensitive amplifier in principle can be.Keywords
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