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

Physical Review A

Quantum theory of a two-mode two-photon correlated spontaneous-emission laser

Ning Lü, Shi-Yao Zhu

Published Mar 1, 1990• 24 citations
Publisher

Abstract

A quantum theory of a two-mode two-photon correlated spontaneous-emission laser is developed. It is shown that the quantum-noise quenching and even nonclassical effects can occur in both the average phase and relative amplitude of the two fields. Near threshold we find a maximum of 50% intracavity squeezing in the two-photon transition limit, with each of the average phase and the relative amplitude contributing 25% squeezing.

DOI
10.1103/physreva.41.2865

Related papers

THE OPERATION IN THE STEADY STATE AND SQUEEZING OF QUANTUM NOISE IN TWO-MODE TWO-PHOTON CORRELATED-SPONTANEOUS-EMISSION LASERS

Xiangming Hu, PENG JIN-SHENG, (1)华中师范大学物理系; (2)华中师范大学应用物理研究所

Operation in the steady state and squeezing of quantum noise in two-mode two-photon correlated-spontaneous-emission lasers(CEL) are studied via nonliner quantum theory.It is shown that the two-mode two-photon CEL exhibits lasing without inversion and two-mode hysteresis even without triggering.The features of squeezing of quantum noise in the relative amplitude and the average phase are given.

Acta Physica Sinica•Jan 1, 1997•3 citations

Quantum theory of two-photon correlated-spontaneous-emission lasers: Exact atom-field interaction Hamiltonian approach

Ning Lü, Shi-Yao Zhu

A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering Q function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state Q functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

Physical Review A•Nov 1, 1989•38 citations

Nonlinear theory of a two-photon correlated-spontaneous-emission laser: A coherently pumped two-level–two-photon laser

Ning Lü, Fang-Xiao Zhao, János A. Bergou

We develop a nonlinear theory of a two-photon correlated-spontaneous-emission laser (CEL) by using an effective interaction Hamiltonian for a two-level system coupled by a two-photon transition. Assuming that the active atoms are prepared initially in a coherent superposition of two atomic levels involved in the two-photon transition, we derive a master equation for the field-density operator by using our quantum theory for coherently pumped lasers. The steady-state properties of the two-photon CEL are studied by converting the field master equation into a Fokker-Planck equation for the antinormal-ordering Q representation of the field-density operator. Because of the injected atomic coherence, the drift and diffusion coefficients become phase sensitive. This leads to laser phase locking and an extra two-photon CEL gain. The laser field can build up from a vacuum in the no-population-inversion region, in contrast to an ordinary two-photon laser for which triggering is needed. We find an approximate steady-state solution of the Q representation for the laser field, which consists of two identical peaks of elliptical type. We calculate the phase variance and, for any given mean photon number, obtain the minimum variance in the phase quadrature as a function of the initial atomic variables. Squeezing of the quantum noise in the phase quadrature is found and it exhibits the following features: (1) it is possible only when the laser intensity is smaller than a certain value; (2) it becomes most significant for small mean photon number, which is achievable in the no-population-inversion region; and (3) a maximum of 50% squeezing can be asymptotically approached in the small laser intensity limit. As a by-product we also study the ordinary two-photon laser and find, e.g., photon-number variance and laser linewidth.

Physical Review A•May 1, 1989•69 citations

Two-photon correlated–spontaneous-emission laser: Quantum noise quenching and squeezing

Marlan O. Scully, K. Wódkiewicz, Muhammad Suhail Zubairy +3 more

Previous studies have shown that the possible utility of the two-photon laser as a squeezed-state generator is negated by spontaneous-emission fluctuations. We here show that a two-photon correlated--spontaneous-emission laser can produce light which is both squeezed and free from spontaneous-emission fluctuations.

Physical Review Letters•May 2, 1988•202 citations

Photon-number correlations near the threshold of microcavity lasers in the weak-coupling regime

R. Jin, Deepak Boggavarapu, M. Sargent +3 more

The quantum-noise properties near the threshold of microcavity lasers are studied theoretically and experimentally in the weak-coupling regime. Computations based on two-level quantum theory show that the microlasers exhibit a high degree of second-order coherence compared with conventional lasers as a result of the suppression of spontaneous emission into nonlasing modes, and that there always exists a finite threshold for these lasers defined by the peak of the photon-number correlation function corresponding to the spontaneous-to-stimulated transition.

Physical Review A•May 1, 1994•62 citations

Polarization correlated-emission laser and the influence of pump statistics

Claus Benkert, Marlan O. Scully

We propose a new kind of correlated-spontaneous-emission laser in which the electromagnetic field is driven by coherently prepared atoms. Such a system constitutes a very simple correlated-emission scheme in that it involves only single-photon transitions, whereas all previous studies were based on correlated photon pairs. We find that for low intensities the fluctuations in the photon number can be reduced below the standard limit while the phase noise is unaffected by the atomic coherence. However, the amount of noise reduction crucially depends on the fluctuations of the pump mechanism. In the high-intensity limit the photon-number fluctuations can be reduced even further. It is possible to achieve a complete quenching of the spontaneous-emission noise and even squeezing, depending on the atomic coherence and the statistical properties of the pump mechanism. Additionally we find a large reduction in the phase fluctuations. In contrast to the amplitude noise, this reduction is independent of the pump noise.

Physical Review A•Sep 1, 1990•22 citations
A quantum theory of a two-mode two-photon correlated spontaneous-emission laser is developed. It is shown that the quantum-noise quenching and even nonclassical effects can occur in both the average phase and relative amplitude of the two fields. Near threshold we find a maximum of 50% intracavity squeezing in the two-photon transition limit, with each of the average phase and the relative amplitude contributing 25% squeezing.
A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering Q function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state Q functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.
We develop a nonlinear theory of a two-photon correlated-spontaneous-emission laser (CEL) by using an effective interaction Hamiltonian for a two-level system coupled by a two-photon transition. Assuming that the active atoms are prepared initially in a coherent superposition of two atomic levels involved in the two-photon transition, we derive a master equation for the field-density operator by using our quantum theory for coherently pumped lasers. The steady-state properties of the two-photon CEL are studied by converting the field master equation into a Fokker-Planck equation for the antinormal-ordering Q representation of the field-density operator. Because of the injected atomic coherence, the drift and diffusion coefficients become phase sensitive. This leads to laser phase locking and an extra two-photon CEL gain. The laser field can build up from a vacuum in the no-population-inversion region, in contrast to an ordinary two-photon laser for which triggering is needed. We find an approximate steady-state solution of the Q representation for the laser field, which consists of two identical peaks of elliptical type. We calculate the phase variance and, for any given mean photon number, obtain the minimum variance in the phase quadrature as a function of the initial atomic variables. Squeezing of the quantum noise in the phase quadrature is found and it exhibits the following features: (1) it is possible only when the laser intensity is smaller than a certain value; (2) it becomes most significant for small mean photon number, which is achievable in the no-population-inversion region; and (3) a maximum of 50% squeezing can be asymptotically approached in the small laser intensity limit. As a by-product we also study the ordinary two-photon laser and find, e.g., photon-number variance and laser linewidth.
The quantum-noise properties near the threshold of microcavity lasers are studied theoretically and experimentally in the weak-coupling regime. Computations based on two-level quantum theory show that the microlasers exhibit a high degree of second-order coherence compared with conventional lasers as a result of the suppression of spontaneous emission into nonlasing modes, and that there always exists a finite threshold for these lasers defined by the peak of the photon-number correlation function corresponding to the spontaneous-to-stimulated transition.
We propose a new kind of correlated-spontaneous-emission laser in which the electromagnetic field is driven by coherently prepared atoms. Such a system constitutes a very simple correlated-emission scheme in that it involves only single-photon transitions, whereas all previous studies were based on correlated photon pairs. We find that for low intensities the fluctuations in the photon number can be reduced below the standard limit while the phase noise is unaffected by the atomic coherence. However, the amount of noise reduction crucially depends on the fluctuations of the pump mechanism. In the high-intensity limit the photon-number fluctuations can be reduced even further. It is possible to achieve a complete quenching of the spontaneous-emission noise and even squeezing, depending on the atomic coherence and the statistical properties of the pump mechanism. Additionally we find a large reduction in the phase fluctuations. In contrast to the amplitude noise, this reduction is independent of the pump noise.