Quantum noise in Josephson-junction parametric amplifiers

Journal Article · Sun May 01 04:00:00 EDT 1983 · IEEE Trans. Magn.; (United States)

DOI:https://doi.org/10.1109/TMAG.1983.1062472· OSTI ID:5483204

Kuzmin, L; Likharev, K; Migulin, V; Zorin, A

Crossover between thermal and quantum noise in the externally-pumped Josephson-junction parametric amplifiers is theoretically followed. Two different approaches are used for the analysis: Josephson junction is replaced with its RSJ model with the equilibrium source of fluctuations; microscopic theory of the tunnel junctions is used, which takes into account not only thermal and quantum but also shot noise. Because of inconvenience of the noise temperature T /SUB N/ for the amplifier sensitivity characterization in the quantum limit, the authors express their results in terms of the figure theta /SUB N/ which is essentially the amplifier output noise energy, reduced to its input (in the classical limit, theta /SUB N/ =k /SUB B/ T /SUB N/). For the nondegenerate amplifier, the minimum value of theta /SUB N/ equals h..omega../2 and is due to quantum noise (zeropoint oscillations) in the idle-frequency resonator of the amplifier. For the degenerate amplifier, sensitive to only one quadrature component of the input signal, theta /SUB N/ can be made much less than the above ''quantum limit'' even at operation temperatures much higher than h..omega../k /SUB B/, if the Josephson junction characteristic frequency ..omega.. /SUB c/ is high enough, h..omega.. /SUB c/ k /SUB B/ T. An analysis of the experimental situation shows that the values theta /SUB N/ < can be achieved using two-dimensional arrays of a large number (N approx. = 100) single-tunnel-junction interferometers with low inductances, inductively coupled to a microwave cavity.

• Research Organization: Dept. of Physics, Moscow State Univ., Moscow 117234
• OSTI ID: 5483204
• Journal Information: IEEE Trans. Magn.; (United States), Journal Name: IEEE Trans. Magn.; (United States) Vol. 19:3; ISSN IEMGA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment &amp; Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFIERS
COUPLING
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
EQUIPMENT
INTERFEROMETERS
JOSEPHSON JUNCTIONS
JUNCTIONS
MEASURING INSTRUMENTS
MECHANICS
MICROWAVE RADIATION
NOISE
QUANTUM MECHANICS
RADIATIONS
RESONATORS
SENSITIVITY
SUPERCONDUCTING JUNCTIONS
TUNNELS
UNDERGROUND FACILITIES