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Lifting the Bandwidth Limit of Optical Homodyne Measurement
  • yaakov shaked
yaakov shaked

Corresponding Author:[email protected]

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Abstract

Homodyne measurement is a corner-stone of quantum optics. It is the major method for measuring the quadratures of light - the optical analog of position and momentum in quantum mechanics. Standard homodyne suffers from an inherent bandwidth limitation due to the use of square-law photo-detectors as a nonlinear multiplier, limiting the bandwidth to the (electronically accessible) GHz range at most. Thus, the study and application of squeezed light - a major resource for processing quantum information, is limited to the very special (near) degenerate squeezing, almost overlooking the general two-mode and broadband squeezing, which inherently requires a homodyne measurement with optical bandwidth. We present a direct optical homodyne technique with practically unlimited bandwidth utilizing optical parametric amplification as the nonlinear multiplier. We demonstrate an optical homodyne measurement of broadband two-mode squeezed light across \(>55\)THz in parallel, with \(\sim\!90\)THz separation between the mode centers using four wave mixing parametric amplification in a photonic crystal fiber. We present a full quantum theoretical treatment along with semi-classical intuition for the use of optical non-linearity for homodyne measurement.