Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of the Optical Society of America B

Detection of squeezed light by directional photoionization of coherently superposed states with different symmetries

Gershon Kurizki, M. Shapiro

Published Feb 1, 1991• 5 citations
Publisher

Abstract

We introduce a new approach to photodetection, based on absorbers (atoms, molecules, or dopant donors in semiconductors) that are kept in a steady superposition of two bound states having different spatial symmetries (e.g., s and p0). We consider the illumination of such absorbers by a superposition of two fields that are mutually orthogonal by virtue of polarization or frequency, and measurements of the resulting photocurrent along the direction of polarization of one of the fields. In contrast to conventional photon counters, the directional photocurrent generated in the considered scheme measures only the phase-sensitive cross products of the mutually orthogonal field amplitudes, without responding to the photon flux of each mode separately. If the light is a superposition of a one- or two-mode squeezed vacuum field and a nearly coherent (local-oscillator) field orthogonal to the former, then cross correlations between two such photocurrents yield the autocorrelation function of the squeezed-field quadrature without terms related to the noise of the local oscillator (although shot noise still affects the degree of accuracy to which the autocorrelation is measured).

DOI
10.1364/josab.8.000355

Related papers

Squeezed states of light

Harry J. Kimble

Squeezed states of the electromagnetic field are characterized by a reduction of fluctuations for one of two quadrature phase amplitudes below the level of fluctuations for the vacuum state. This reduction is a manifestly quantum or nonclassical feature which is of great interest in its own right but also potentially important for precision measurement with sensitivity beyond the shot-noise or vacuum-state limit. We describe three different experiments in which squeezed light has been generated in our laboratory involving parametric downconversion, intracavity frequency doubling, and optical bistability with two-state atoms. By employing the squeezed light produced by a subthreshold optical parametric oscillator, we have achieved improvements in sensitivity beyond the vacuum-state limit for the detection of both phase and amplitude changes of the electromagnetic field. An alternate route to sensitivity beyond the vacuum-state limit is through quantum nondemolition measurement, where we have suggested and are implementing a scheme involving parametric conversion and polarization mixing.

Annual Meeting Optical Society of America•Jan 1, 1988•0 citations

Spectrum of squeezing and photocurrent shot noise: a normally ordered treatment

H. J. Carmichael

The detection of squeezed optical fields generated by intracavity nonlinear-optical interactions is described. The relationship between quantum-statistical properties of the cavity mode and those of the field at a detector placed outside the cavity discussed. The detected field is composed of a source field from the cavity plus a free external field. The free field couples weakly to the cavity so that it is correlated with the source field. The photocurrent spectrum in optical homodyne detection is calculated, and the spectrum of squeezing is defined. This spectrum can be calculated entirely in terms of intracavity fields without requiring knowledge of the correlations between source and free-field contributions in the cavity output. This follows from an explicitly normally ordered, time-ordered treatment of the photodetection problem. Contrasting earlier treatments of photodetection for squeezed fields, in a normally ordered approach, shot noise arises naturally from the self-correlation of photocurrent for pulses. The derived spectrum is converted into nonnormally ordered, non-time-ordered form to recover the results of these earlier treatments and their interpretation of shot noise in terms of local-oscillator quantum noise, signal and quantum noise, and detector-efficiency quantum noise.

Journal of the Optical Society of America B•Oct 1, 1987•142 citations

Correlation spectroscopy with squeezed light

V. V. Batygin, Dmitriy V. Kupriyanov, Igor M. Sokolov

We have discussed the possibilities of correlation spectroscopy (light beating spectroscopy) technique if squeezed light is used as a probe radiation for medium monitoring. The dispersion of the fluctuation of photocurrent spectrum measured in this method is expressed in terms of fourth order photocurrent correlation function. This correlation function is considered and evaluated in assumptions of photodetection theory developed by Glauber in first nonvanishing orders in interaction of probe light with the atoms of a photodetector. We show that fourth order correlation function is determined by all field TN-ordered amplitude correlation functions up to the fourth order. In case of heterodyne detection, when the light incident on photodetector surface is the mix of strong coherent modes of local oscillator wave and weak non-coherent (squeezed) modes, the observable (photocurrent spectrum) as well as its fluctuation (noise of photocurrent spectrum) is expressed in terms of spectrum-dependent Mandel parameter. We have discussed possible improvement of sensitivity limit for correlation spectroscopy in this case.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 6, 1996•0 citations

Direct detection of Gaussian state light

Jeffrey H. Shapiro, Ke-Xun Sun

The quantum theory of photodetection is applied to the direct detection of multi-mode Gaussian-state light, with particular attention to the mean photocurrent and the photocurrent noise spectrum. Gaussian-state light comprises squeezed-state light plus additional classical Gaussian noise. By extending the familiar Gaussian moment-factoring formula of classical statistics to the antinormally ordered characteristic function of Gaussian-state light, the first and second moment photocurrent statistics for such illumination are shown to be completely characterized by knowledge of the mean function, the phase-sensitive correlation function, and the normally ordered correlation of the input light. The theory delineates the condition under which the strong-mean-field approximation is applicable to direct detection of such beams, i.e., it tells us when a direct detector yields the same noise spectrum as that of an in-phase homodyne detector. Numerical results are presented for the noise spectra of a squeezed amplifier, i.e., an optical parametric amplifier with signal-injection-induced gain saturation.

Annual Meeting Optical Society of America•Jan 1, 1992•0 citations

Quantum correlations of quadrature amplitudes in nondegenerate parametric downconversion

Silvania F. Pereira, K. C. Peng, Harry J. Kimble

For measurements describable by a discrete set of possibilities, numerous demonstrations of the violation of Bell's inequalities have been reported in optical physics based on observations of polarization correlations for photon pairs. By contrast for observables with a continuous spectrum, there appears to be no general inequalities corresponding to those of Bell and no experimental realization of the original Einstein-Podolsky-Rosen paradox. Following Reid and Drummond,1 we are attempting to demonstrate the EPR paradox in the context of the measurement of continuous quantum variables with a subthreshold optical parametric oscillator operated in a frequency degenerate but polarization nondegenerate mode. In this case, the EPR paradox is formulated in terms of two sets of quadrature phase amplitudes for the spatially separated signal and idler fields. As the parametric gain is increased toward threshold, the quadrature amplitudes of the signal and idler beams become increasingly faithful quantum copies of one another. Our measurements of quadrature amplitudes are carried out using independent balanced homodyne detectors at two sites. When operated for the detection of squeezing at one site, noise reductions of 4 dB relative to the vacuum state limit are observed, which is most encouraging since noise reductions >3 dB in the difference photocurrent from the two sites are sufficient for inference at a distance of a signal observable from a measurement of the corresponding idler variable.

Annual Meeting Optical Society of America•Jan 1, 1989•0 citations

Balanced-heterodyne detection of sub-shot-noise optical signals

Sheng Feng, Lu, Zehuan, Jie Zhang +1 more

As part of the effort to make use of squeezed states of light for detection of sub-shot-noise optical signals, we study the balanced heterodyne scheme, for which the corresponding spectral density of the photocurrent fluctuations produced at the output of the detector is calculated as the Fourier transform of their autocorrelation function. Our analysis shows that, for maximal signal-to-noise ratio enhancement by use of squeezed states of light, an optical signal to be measured must be carried in the squeezed quadrature of the carrier field. We discuss how "the additional heterodyne noise" can be eliminated in this scheme and its potential application to gravitational-wave searching. To demonstrate the practical feasibility, we propose and study a phase-locking technique for this scheme.

arXiv:1112.3155•Dec 14, 2011•1 citation
We introduce a new approach to photodetection, based on absorbers (atoms, molecules, or dopant donors in semiconductors) that are kept in a steady superposition of two bound states having different spatial symmetries (e.g., s and p0). We consider the illumination of such absorbers by a superposition of two fields that are mutually orthogonal by virtue of polarization or frequency, and measurements of the resulting photocurrent along the direction of polarization of one of the fields. In contrast to conventional photon counters, the directional photocurrent generated in the considered scheme measures only the phase-sensitive cross products of the mutually orthogonal field amplitudes, without responding to the photon flux of each mode separately. If the light is a superposition of a one- or two-mode squeezed vacuum field and a nearly coherent (local-oscillator) field orthogonal to the former, then cross correlations between two such photocurrents yield the autocorrelation function of the squeezed-field quadrature without terms related to the noise of the local oscillator (although shot noise still affects the degree of accuracy to which the autocorrelation is measured).
Squeezed states of the electromagnetic field are characterized by a reduction of fluctuations for one of two quadrature phase amplitudes below the level of fluctuations for the vacuum state. This reduction is a manifestly quantum or nonclassical feature which is of great interest in its own right but also potentially important for precision measurement with sensitivity beyond the shot-noise or vacuum-state limit. We describe three different experiments in which squeezed light has been generated in our laboratory involving parametric downconversion, intracavity frequency doubling, and optical bistability with two-state atoms. By employing the squeezed light produced by a subthreshold optical parametric oscillator, we have achieved improvements in sensitivity beyond the vacuum-state limit for the detection of both phase and amplitude changes of the electromagnetic field. An alternate route to sensitivity beyond the vacuum-state limit is through quantum nondemolition measurement, where we have suggested and are implementing a scheme involving parametric conversion and polarization mixing.
The detection of squeezed optical fields generated by intracavity nonlinear-optical interactions is described. The relationship between quantum-statistical properties of the cavity mode and those of the field at a detector placed outside the cavity discussed. The detected field is composed of a source field from the cavity plus a free external field. The free field couples weakly to the cavity so that it is correlated with the source field. The photocurrent spectrum in optical homodyne detection is calculated, and the spectrum of squeezing is defined. This spectrum can be calculated entirely in terms of intracavity fields without requiring knowledge of the correlations between source and free-field contributions in the cavity output. This follows from an explicitly normally ordered, time-ordered treatment of the photodetection problem. Contrasting earlier treatments of photodetection for squeezed fields, in a normally ordered approach, shot noise arises naturally from the self-correlation of photocurrent for pulses. The derived spectrum is converted into nonnormally ordered, non-time-ordered form to recover the results of these earlier treatments and their interpretation of shot noise in terms of local-oscillator quantum noise, signal and quantum noise, and detector-efficiency quantum noise.
We have discussed the possibilities of correlation spectroscopy (light beating spectroscopy) technique if squeezed light is used as a probe radiation for medium monitoring. The dispersion of the fluctuation of photocurrent spectrum measured in this method is expressed in terms of fourth order photocurrent correlation function. This correlation function is considered and evaluated in assumptions of photodetection theory developed by Glauber in first nonvanishing orders in interaction of probe light with the atoms of a photodetector. We show that fourth order correlation function is determined by all field TN-ordered amplitude correlation functions up to the fourth order. In case of heterodyne detection, when the light incident on photodetector surface is the mix of strong coherent modes of local oscillator wave and weak non-coherent (squeezed) modes, the observable (photocurrent spectrum) as well as its fluctuation (noise of photocurrent spectrum) is expressed in terms of spectrum-dependent Mandel parameter. We have discussed possible improvement of sensitivity limit for correlation spectroscopy in this case.
The quantum theory of photodetection is applied to the direct detection of multi-mode Gaussian-state light, with particular attention to the mean photocurrent and the photocurrent noise spectrum. Gaussian-state light comprises squeezed-state light plus additional classical Gaussian noise. By extending the familiar Gaussian moment-factoring formula of classical statistics to the antinormally ordered characteristic function of Gaussian-state light, the first and second moment photocurrent statistics for such illumination are shown to be completely characterized by knowledge of the mean function, the phase-sensitive correlation function, and the normally ordered correlation of the input light. The theory delineates the condition under which the strong-mean-field approximation is applicable to direct detection of such beams, i.e., it tells us when a direct detector yields the same noise spectrum as that of an in-phase homodyne detector. Numerical results are presented for the noise spectra of a squeezed amplifier, i.e., an optical parametric amplifier with signal-injection-induced gain saturation.
For measurements describable by a discrete set of possibilities, numerous demonstrations of the violation of Bell's inequalities have been reported in optical physics based on observations of polarization correlations for photon pairs. By contrast for observables with a continuous spectrum, there appears to be no general inequalities corresponding to those of Bell and no experimental realization of the original Einstein-Podolsky-Rosen paradox. Following Reid and Drummond,1 we are attempting to demonstrate the EPR paradox in the context of the measurement of continuous quantum variables with a subthreshold optical parametric oscillator operated in a frequency degenerate but polarization nondegenerate mode. In this case, the EPR paradox is formulated in terms of two sets of quadrature phase amplitudes for the spatially separated signal and idler fields. As the parametric gain is increased toward threshold, the quadrature amplitudes of the signal and idler beams become increasingly faithful quantum copies of one another. Our measurements of quadrature amplitudes are carried out using independent balanced homodyne detectors at two sites. When operated for the detection of squeezing at one site, noise reductions of 4 dB relative to the vacuum state limit are observed, which is most encouraging since noise reductions >3 dB in the difference photocurrent from the two sites are sufficient for inference at a distance of a signal observable from a measurement of the corresponding idler variable.
As part of the effort to make use of squeezed states of light for detection of sub-shot-noise optical signals, we study the balanced heterodyne scheme, for which the corresponding spectral density of the photocurrent fluctuations produced at the output of the detector is calculated as the Fourier transform of their autocorrelation function. Our analysis shows that, for maximal signal-to-noise ratio enhancement by use of squeezed states of light, an optical signal to be measured must be carried in the squeezed quadrature of the carrier field. We discuss how "the additional heterodyne noise" can be eliminated in this scheme and its potential application to gravitational-wave searching. To demonstrate the practical feasibility, we propose and study a phase-locking technique for this scheme.