Experimental study of a phase-sensitive heterodyne detector

Abstract

It is believed that the quantum behaviors of homodyne detectors and traditional heterodyne detectors can be fully understood in the context of the quantum theory of optical detection. According to the theory, a 3 dB extra quantum noise has been predicted in a traditional heterodyne detector, as a phase-insensitive device, due to the existence of the image sideband vacuum. However, regarding the noise performance of a phase-sensitive heterodyne detector, a fundamental dilemma inevitably arises: On one hand, the detector should suffer the 3 dB noise penalty caused by the image sideband vacuum, on the other hand, it, as a phase-sensitive device, should be noise free at the quantum level. We report on an experiment on the quantum noise performance of a phase-sensitive heterodyne detector with a bichromatic local oscillator. The results show that the studied detector is noise free, i.e., the quantum noise of the image sideband vacuum is absent in the observation. Revealing the mechanism for the absence of the image vacuum noise will be important for a full understanding of the origin of the quantum noise in optical detection.

Frequency-resolved optical mode decomposition of multimode quantum fields

“…Early studies were focused on the unbalanced homodyne and heterodyne [4,11], and later shifted to the balanced ones [12][13][14][15] for the advantageous suppression of the local oscillator (LO) excess noise. Since the above monochromatic-LO heterodyne has extra 3 dB noise compared to the homodyne [16] due to the vacuum fluctuation of the image band field [17], the bichromatic-LO heterodyne was proposed and proven to be free of this noise theoretically [9,16,18] and experimentally [19]. This scheme has recently been applied to detection of the broadband quadrature squeezing [20] and to the heterodyne readout in gravitational-wave detectors [21].…”

Two-Carrier Scheme: Evading the 3 dB Quantum Penalty of Heterodyne Readout in Gravitational-Wave Detectors

“…Is there a way to evade the fundamental quantum noise penalty with a heterodyne readout? It was found that the noise penalty of a heterodyne readout could be evaded if the image vacuum fields can be excited to contain coherent signal flux [14,22,23]. Inspired by this finding, we give a new gravitational wave detector scheme that includes two carriers at ω 1 and ω 2 with a beam at ω L ¼ ðω 1 þ ω 2 Þ=2 serving as the heterodyne LO.…”