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Quantum analysis of second-order effects in superconducting travelling-wave parametric amplifiers
- Publication Year :
- 2021
- Publisher :
- IOP Publishing, 2021.
-
Abstract
- We have performed a quantum mechanical analysis of travelling-wave parametric amplifiers (TWPAs) in order to investigate five experimental phenomena related to their operations, namely the effect of impedance mismatch, the presence of upper idler modes, the presence of quantum and thermal noise, the generation of squeezed states, and the preservation of pre-squeezed states during amplification. Our analysis uses momentum operators to describe the spatial evolution of quantised modes along a TWPA. We calculate the restriction placed on pump amplitude as well as amplifier gain as a result of impedance mismatch between a TWPA and its external system. We apply our analysis to upper idler modes and demonstrate that they will result in suppressed gain. We show that an ideal TWPA is indeed quantum-limited—i.e. it introduces a half-quantum of zero-point fluctuation which is the minimum possible noise contribution for a phase-preserving linear amplifier. We analyse the thermal noise associated with a TWPA by considering the effect of distributed sources along an amplifier transmission line. Our analysis predicts a doubling of thermal noise in the high gain limit as a result of wave-mixing between signal and idler modes. We study the operation of a TWPA in the presence of a DC bias current, and have shown that highly squeezed states can in principle be generated. However, amplifying a pre-squeezed state using a non-degenerate TWPA generally reduces the squeezing advantage.
- Subjects :
- Paper
Acoustics and Ultrasonics
thermal noise
Condensed matter
FOS: Physical sciences
Noise (electronics)
superconducting amplifier
Condensed Matter - Strongly Correlated Electrons
Transmission line
Object-relational impedance mismatch
Linear amplifier
Instrumentation and Methods for Astrophysics (astro-ph.IM)
Physics
Quantum Physics
Strongly Correlated Electrons (cond-mat.str-el)
Amplifier
Quantum noise
quantum noise
Condensed Matter Physics
Surfaces, Coatings and Films
Electronic, Optical and Magnetic Materials
parametric amplifier
Quantum electrodynamics
Parametric oscillator
Astrophysics - Instrumentation and Methods for Astrophysics
Quantum Physics (quant-ph)
DC bias
Subjects
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....9c648e9c80f06f8e7cce8208b3b29223