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Optics Letters

Observation of squeezed noise produced by forward four-wave mixing in sodium vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

Published Mar 1, 1987• 164 citations
Publisher

Abstract

We have generated squeezed-state light through forward four-wave mixing in sodium vapor as verified by homodyne detection. Optical phase-sensitive noise with a minimum falling 4% below the shot-noise limit was observed.
DOI
10.1364/ol.12.000161

Related papers

Squeezing experiments in sodium vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

We describe our efforts to observe squeezing, and related nonclassical effects, in three forward four-wave mixing experiments using sodium vapor as a nonlinear medium. In a single-beam experiment with homodyne detection, we found optically phase-sensitive noise, which was radio-frequency phase insensitive, in a cw dye-laser beam that had propagated through sodium vapor. The minima of the phase-sensitive noise were always at or above the coherent-state value. In our forward four-wave mixing experiment with probe–conjugate-beam direct detection and correlation, we found that the sodium-vapor interaction produced positive noise correlation between the probe and conjugate beams. The correlation, however, did not exceed the excess noises on these beams, so that a nonclassical behavior was not demonstrated. Finally, our forward four-wave mixing experiment with probe–conjugate-beam combination and homodyne detection did demonstrate the generation of squeezed-state light in our setup. Optically phase-sensitive noise with a minimum falling 4% below the coherent-state level was observed.

Journal of the Optical Society of America B•Oct 1, 1987•27 citations

Observation of Phase-Sensitive Noise in Sodium Vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

Squeezed states of light exhibit phase-sensitive quantum noise, which can be measured via optical homodyne detection. Squeezed state generation has been predicted in degenerate four-wave mixing, resonance fluorescence, and nonlinear propagation. We report observing phase-sensitive noise via optical homodyning on a cw dye laser beam which has propagated through sodium vapor near the D-lines.

International Meeting on Instabilities and Dynamics of Lasers and Nonlinear Optical Systems•Jan 1, 1985•0 citations

Squeezed state experiments in sodium vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

Squeezed states of light exhibit phase-sensitive quantum noise which falls below the semiclassical shot noise limit. We report results from experiments in sodium vapor to observe squeezed light. In a single-beam experiment, a dye laser beam transmitted through sodium vapor was homodyned. Phase-sensitive noise on the radio frequency off­set modes was observed at or above the semiclassical limit.1 In a two-beam correlation experiment, the transmitted probe and the reflected con­jugate beams in forward four-wave mixing were direct detected. Although this configuration does not generate squeezed light, the subtracted photo­current exhibits subshot noise fluctuations.2 Phase-insensitive noise above the semiclassical limit was observed with a strong positive correlation between the probe and the conjugate photo­currents. In a squeezed state experiment, a probe-conjugate combination mode of forward four-wave mixing was homodyned.3 With the input beam blocked, the noise showed nonclassical phase-sensitivity with a minimum of 0.2 dB below the vacuum state limit. When only the probe or the conjugate beam was homodyned, the noise remained phase-insensitive near the vacuum state level.

Annual Meeting Optical Society of America•Jan 1, 1986•0 citations

Observation of optical phase-sensitive noise on a light beam transmitted through sodium vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

We have observed optical phase-sensitive noise in homodyne detection of a cw light beam which has propagated through sodium vapor near the D lines. Although at present the minimum noise is at or above the vacuum-state quantum limit due to zero-point fluctuations, nevertheless its phase behavior is like that of a squeezed state. Our observations are consistent both with the predictions of the quantum-mechanical theory of degenerate four-wave mixing and the theory of multiatom resonance fluorescence in the forward direction.

Physical Review A•Dec 1, 1985•23 citations

Observation of phase-sensitive noise in sodium vapor

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

Squeezed states of light exhibit phase-sensitive quantum noise measurable via optical homodyne detection. They have been predicted to be generated via degenerate four-wave mixing, resonance fluorescence, and nonlinear propagation.1 We report observing phase-sensitive noise via optical homodyning on a cw dye laser beam which has propagated through sodium vapor near the D lines. A p-polarized dye laser beam of ~5-W/cm2 intensity was passed through sodium vapor near its D lines. Homodyne measurements were made on both the s- and the p-polarized components of the transmitted beam using the dual-detector subtraction scheme.2 A spectrum analyzer monitored the noise in a 6–15-MHz band. In the absence of sodium, the noise in this band was vacuum-state quantum noise limited and was insensitive to the relative local-oscillator beam/transmitted laser beam phase θ. In the presence of sodium, the noise was sensitive to θ, with dependence of the form As,p + Bs,p cos2(θ − ϕs,p), where ϕs = 0 for s polarization and ϕp = π/2 for p polarization. For one set of data we measured As = 2 dB, Bs = 3 dB, Ap = 3 dB, and Bp = 2.5 dB above the noise levels in the absence of sodium. The s-poiarization data were collected with the local-oscillator power PLO far in excess of the s component of the transmitted pump power PTP; for p polarization, PLO ~ PTP prevailed. The measurement uncertainty in the spectrum analyzer data is ±0.5 dB. Possible physical mechanisms to explain these results are discussed.

Annual Meeting Optical Society of America•Jan 1, 1985•0 citations

Observation of squeezed noise produced by forward four-wave mixing in sodium vapor (A)

Mari W. Maeda, Prem Kumar, Jeffrey H. Shapiro

Journal of the Optical Society of America B•Feb 1, 1986•0 citations
We describe our efforts to observe squeezing, and related nonclassical effects, in three forward four-wave mixing experiments using sodium vapor as a nonlinear medium. In a single-beam experiment with homodyne detection, we found optically phase-sensitive noise, which was radio-frequency phase insensitive, in a cw dye-laser beam that had propagated through sodium vapor. The minima of the phase-sensitive noise were always at or above the coherent-state value. In our forward four-wave mixing experiment with probe–conjugate-beam direct detection and correlation, we found that the sodium-vapor interaction produced positive noise correlation between the probe and conjugate beams. The correlation, however, did not exceed the excess noises on these beams, so that a nonclassical behavior was not demonstrated. Finally, our forward four-wave mixing experiment with probe–conjugate-beam combination and homodyne detection did demonstrate the generation of squeezed-state light in our setup. Optically phase-sensitive noise with a minimum falling 4% below the coherent-state level was observed.
Squeezed states of light exhibit phase-sensitive quantum noise which falls below the semiclassical shot noise limit. We report results from experiments in sodium vapor to observe squeezed light. In a single-beam experiment, a dye laser beam transmitted through sodium vapor was homodyned. Phase-sensitive noise on the radio frequency off­set modes was observed at or above the semiclassical limit.1 In a two-beam correlation experiment, the transmitted probe and the reflected con­jugate beams in forward four-wave mixing were direct detected. Although this configuration does not generate squeezed light, the subtracted photo­current exhibits subshot noise fluctuations.2 Phase-insensitive noise above the semiclassical limit was observed with a strong positive correlation between the probe and the conjugate photo­currents. In a squeezed state experiment, a probe-conjugate combination mode of forward four-wave mixing was homodyned.3 With the input beam blocked, the noise showed nonclassical phase-sensitivity with a minimum of 0.2 dB below the vacuum state limit. When only the probe or the conjugate beam was homodyned, the noise remained phase-insensitive near the vacuum state level.
We have observed optical phase-sensitive noise in homodyne detection of a cw light beam which has propagated through sodium vapor near the D lines. Although at present the minimum noise is at or above the vacuum-state quantum limit due to zero-point fluctuations, nevertheless its phase behavior is like that of a squeezed state. Our observations are consistent both with the predictions of the quantum-mechanical theory of degenerate four-wave mixing and the theory of multiatom resonance fluorescence in the forward direction.
Squeezed states of light exhibit phase-sensitive quantum noise measurable via optical homodyne detection. They have been predicted to be generated via degenerate four-wave mixing, resonance fluorescence, and nonlinear propagation.1 We report observing phase-sensitive noise via optical homodyning on a cw dye laser beam which has propagated through sodium vapor near the D lines. A p-polarized dye laser beam of ~5-W/cm2 intensity was passed through sodium vapor near its D lines. Homodyne measurements were made on both the s- and the p-polarized components of the transmitted beam using the dual-detector subtraction scheme.2 A spectrum analyzer monitored the noise in a 6–15-MHz band. In the absence of sodium, the noise in this band was vacuum-state quantum noise limited and was insensitive to the relative local-oscillator beam/transmitted laser beam phase θ. In the presence of sodium, the noise was sensitive to θ, with dependence of the form As,p + Bs,p cos2(θ − ϕs,p), where ϕs = 0 for s polarization and ϕp = π/2 for p polarization. For one set of data we measured As = 2 dB, Bs = 3 dB, Ap = 3 dB, and Bp = 2.5 dB above the noise levels in the absence of sodium. The s-poiarization data were collected with the local-oscillator power PLO far in excess of the s component of the transmitted pump power PTP; for p polarization, PLO ~ PTP prevailed. The measurement uncertainty in the spectrum analyzer data is ±0.5 dB. Possible physical mechanisms to explain these results are discussed.