Physical Review · 1962 · 319 citations · 3 references
Natural SciencesElectrical EngineeringPhysicsAnalog ElectronicsQuantum MechanicsUncertainty QuantificationNoiseNoise MeasurementQuantum MeasurementQuantum OperatorsQuantum StatesNoise FigureNoise Figure AnalysisNoise In AmplifiersOperatorsPhase NoiseQuantum Mechanical ModelQuantum Noise ModelsSignal-to-noise Ratio
Quantum noise dominates in linear amplifiers, prompting a redefinition of the noise figure in terms of uncertainty noise and the derivation of general quantum mechanical equations that encompass masers, parametric amplifiers, and up‑converters. Using general quantum mechanical equations constrained by linearity and commutator conservation, the authors derive the noise figure of a general linear amplifier. The derived noise figure attains a minimum value of 2, and the authors discuss its implications for simultaneous phase and amplitude measurement.
The classical definition of noise figure, based on signal-to-noise ratio, is adapted to the case when quantum noise is predominant. The noise figure is normalized to "uncertainty noise." General quantum mechanical equations for linear amplifiers are set up using the condition of linearity and the requirement that the commutator brackets of the pertinent operators are conserved in the amplification. These equations include as special cases the maser, the parametric amplifier, and the parametric up-converter. Using these equations the noise figure of a general amplifier is derived. The minimum value of this noise figure is equal to 2. The significance of the result with regard to a simultaneous phase and amplitude measurement is explored.
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Quantum Fluctuations and Noise in Parametric Processes. I.
W. H. Louisell, A. Yariv, A. E. Siegman · Physical Review · 1961 · 718 citations
Induced and Spontaneous Emission in a Coherent Field
I. R. Senitzky · Physical Review · 1958 · 67 citations