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Amplification of vacuum fluctuations by two-beam coupling in atomic vapors

Martti Olavi Kauranen, Alexander L. Gaeta, Robert W. Boyd +1 more

We show both theoretically and experimentally that fluctuations of a weak probe beam are increased above the coherent-state shot-noise level as the beam interacts with a strong degenerate pump beam in an atomic vapor. The origin of this noise amplification process is the two-beam-coupling process between the pump beam and the vacuum sidebands of the probe beam. The major contribution to this excess noise arises from the quantum fluctuations of the atomic medium that are induced by the pump beam. We believe that this mechanism can be important in preventing the reduction of noise below the quantum-noise limit in experiments that utilize atomic vapors.We show both theoretically and experimentally that fluctuations of a weak probe beam are increased above the coherent-state shot-noise level as the beam interacts with a strong degenerate pump beam in an atomic vapor. The origin of this noise amplification process is the two-beam-coupling process between the pump beam and the vacuum sidebands of the probe beam. The major contribution to this excess noise arises from the quantum fluctuations of the atomic medium that are induced by the pump beam. We believe that this mechanism can be important in preventing the reduction of noise below the quantum-noise limit in experiments that utilize atomic vapors.

Physical Review AAug 1, 199421 citations

Reduction of Quantum Noise in Atomic Systems

Miguel Orszag

Springer eBooksJan 1, 19890 citations

Theoretical and experimental aspects of quantum noise reduction and precision measurement

Roy S. Bondurant

Jan 1, 19830 citations

Excess Noise Introduced by Beam Propagation Through an Atomic Vapor

Martti Olavi Kauranen, Alexander L. Gaeta, William V. Davis +1 more

We propose and show experimental evidence of a mechanism that is important in reducing the amount of noise reduction that can be achieved at low (<100 MHz) frequencies utilizing atomic vapors as the nonlinear medium.1 The mechanism is based on the two-beam-coupling gain2 experienced by the vacuum sidebands of a weak probe wave as it interacts with a strong degenerate pump wave in an atomic vapor. The mechanism leads to the amplification of intensity fluctuations of an initially shot-noise-limited probe field.We propose and show experimental evidence of a mechanism that is important in reducing the amount of noise reduction that can be achieved at low (<100 MHz) frequencies utilizing atomic vapors as the nonlinear medium.1 The mechanism is based on the two-beam-coupling gain2 experienced by the vacuum sidebands of a weak probe wave as it interacts with a strong degenerate pump wave in an atomic vapor. The mechanism leads to the amplification of intensity fluctuations of an initially shot-noise-limited probe field.

Nonlinear OpticsJan 1, 19920 citations

Quantum Noise Reduction 1

Miguel Orszag

Springer eBooksJan 1, 20240 citations

Excess noise imparted on a laser beam after it propagates through atomic-potassium vapor

William V. Davis, Martti Olavi Kauranen, Russell J. Gehr +2 more

We have observed that a single laser beam that has propagated through an atomic potassium vapor can acquire excess noise. In particular, we find that even if the incident laser beam is shot noise limited, the transmitted laser beam contains noise in excess of its shot noise limit. We interpret this observation in terms of the amplification of vacuum sidemodes of the incident laser beam through forward four-wave mixing processes. These amplified sidebands then beat with the incident laser beam at the photodetector to create excess noise. The excess noise is maximum when the laser frequency is detuned from the potassium resonance by approximately one linewidth on either side of the resonance. We are presently developing a quantitative theoretical model to describe the process that produces this excess noise. We believe that this excess noise can degrade the noise properties of any nonlinear optical interaction that utilizes atomic vapors.We have observed that a single laser beam that has propagated through an atomic potassium vapor can acquire excess noise. In particular, we find that even if the incident laser beam is shot noise limited, the transmitted laser beam contains noise in excess of its shot noise limit. We interpret this observation in terms of the amplification of vacuum sidemodes of the incident laser beam through forward four-wave mixing processes. These amplified sidebands then beat with the incident laser beam at the photodetector to create excess noise. The excess noise is maximum when the laser frequency is detuned from the potassium resonance by approximately one linewidth on either side of the resonance. We are presently developing a quantitative theoretical model to describe the process that produces this excess noise. We believe that this excess noise can degrade the noise properties of any nonlinear optical interaction that utilizes atomic vapors.

Annual Meeting Optical Society of AmericaJan 1, 19930 citations

Excess Noise in Quantum Noise Reduction Experiments Utilizing Atomic Vapors

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Excess Noise in Quantum Noise Reduction Experiments Utilizing Atomic Vapors

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