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

arXiv:quant-ph/0405019 · Journal of Modern Optics

Parametric oscillation with squeezed vacuum reservoirs

A. Mebrahtu

Published Apr 15, 2005• 12 citations
arXivHTMLPDF

Abstract

Employing the quantum Hamiltonian describing the interaction of a two-mode light (signal–idler modes) generated by a non-degenerate parametric oscillator (NDPO) with two uncorrelated squeezed vacuum reservoirs (USVR), we derive the master and the Fokker–Planck equations. The corresponding Fokker–Planck equation for the Q-function is then solved employing a propagator method developed by K. Fesseha [J. Math. Phys. 33 2179 (1992)]. Making use of this Q-function, we calculate the quadrature fluctuations of the optical system. From these results we infer that the signal–idler modes are in squeezed states. When the NDPO operates below threshold we show that, for a large squeezing parameter, a squeezing amounting to a noise suppression approaching 100% below the vacuum level in one of the quadratures can be achieved.

DOI
10.1080/0950034042000275414

Related papers

Quadrature squeezing in a degenerate optical parametric oscillator in the above-threshold regime

Kokeb B. Benti, Desalegn Ayehu

A degenerate optical parametric oscillator (DOPO) in the above threshold regime is a prominent source of squeezed field. In this study, a driven DOPO whose pump mode is coupled to a thermal bath while the signal mode is coupled to a squeezed vacuum reservoir is explored to understand the effect of the external squeezed light and the thermal fluctuations on the squeezing properties of both the intracavity and output pump and signal modes. Our findings showed that the injected squeezed vacuum reservoir enables the intracavity squeezing to surpass the maximum squeezing limit of 50% attainable in a DOPO coupled to an ordinary vacuum reservoir. We also found that the maximum squeezing of the output signal mode shifts from resonance to off-resonance in the presence of the injected squeezed vacuum field. Furthermore, the output pump mode exhibits nearly perfect squeezing for a squeezing parameter of r=2. Unlike the output signal mode, the maximum squeezing of the output pump mode occurs at resonance in the presence of the injected squeezed vacuum reservoir. Moreover, a considerable amount of squeezing is observed even in the presence of thermal fluctuations, as they are counterbalanced by the external squeezed light. Notably, relative damping rate between the pump and signal modes is observed to be a parameter that significantly influences squeezing, indicating the importance of optimizing the amount of damping depending on the intended purpose of the DOPO.

Results in Optics•Mar 1, 2026•0 citations

Two-Mode Squeezed and Entangled Light Production in Parametric Oscillations

Desalegn Ayehu

We investigate the statistical and quadrature squeezings, as well as the entanglement properties, of a two-mode light generated by non-degenerate parametric oscillations coupled to a two-mode squeezed vacuum reservoir, by employing the solutions of the quantum Langevin equations. It is found that the two-mode light shows the two-mode squeezing and entanglement for all values of the time. Moreover, it is observed that the squeezed vacuum reservoir and the growing amplitude of the pump mode enhance the degrees of two-mode squeezing and entanglement. We have also shown that the amounts of squeezing and entanglement are significant in a region, where the mean photon number is higher, and the photon number correlation is lower.

Ukrainian Journal of Physics•Sep 8, 2021•4 citations

Theory of Quantum Entanglement of Intra-Cavity Photons Produced by a Non-Degenerate Parametric Oscillator (Ndpo):

Tamirat Abebe, Nebiyu Gemechu, Milkessa Gebeyehu

The von-Neumann entropy (VNE), usually expressed in terms of the density operator, isthe mathematical tool to measure the degree of entanglement of a bi-partite system.Applying the solutions of the quantum Langevin equations, the anti-normally orderedcharacteristic function of the intra-cavity photons produced by a non-degenerateparametric oscillator could be calculated. With the help of the resulting characteristicfunction, the Q- function which is then used to calculate the entanglement of the intra-cavity photons using VNE is determined. Moreover, the photon number distribution, themean photon number, the normalized second order correlation function, the intensitydifference, and quadrature variance for the intra-cavity photons produced by a non-degenerate parametric oscillator coupled to a two-mode squeezed vacuum reservoir isdetermined. It was found that when the squeeze parameter increases the entanglement alsoincreases. These show that the entropy entanglement has a direct relation with squeezing.

•Jan 1, 2019•0 citations

Entangled light in transition through the generation threshold

Gagik Yu. Kryuchkyan, L. A. Manukyan

We investigate continuous-variable entangling resources on the basis of two-mode squeezing for all operational regimes of a nondegenerate optical parametric oscillator with allowance for quantum noise of an arbitrary level. The results for the quadrature variances of a pair of generated modes are obtained by using the exact steady-state solution of the Fokker-Planck equation for the complex-$P$-representation quasiprobability distribution function. We find a simple expression for the squeezed variances in the near-threshold range and conclude that the maximal two-mode squeezing reaches 50% relative to the level of vacuum fluctuations and is achieved at the pump field intensity close to the generation threshold. The distinction between the degrees of two-mode squeezing for monostable and bistable operational regimes is cleared up.

arXiv:quant-ph/0304205•Physical Review A•Jan 22, 2004•20 citations

Effect of squeezing on the degenerate parametric oscillator

Javed Anwar, Muhammad Suhail Zubairy

The effect of squeezing on the degenerate parametric oscillator is studied. It is shown that when the ordinary-vacuum reservoir is replaced by a squeezed-vacuum reservoir, the maximum 50% limit of the second-order squeezing inside the cavity can be crossed. It is also shown that the mean number of photons increases considerably. An exact steady-state solution for the Fokker-Planck equation for the field mode is also presented. The photon distribution for the intracavity field and the higher-order variances have been obtained by using the solution of this equation.

Physical Review A•Feb 1, 1992•40 citations

Theory of Quantum Entanglement of Intra-Cavity Photons Produced by a Non-Degenerate Parametric Oscillator (Ndpo): Semi-Classical Approach

Tamirat Abebe, Nebiyu Gemechu, Milkessa Gebeyehu

The von-Neumann entropy (VNE), usually expressed in terms of the density operator, is the mathematical tool to measure the degree of entanglement of a bi-partite system. Applying the solutions of the quantum Langevin equations, the anti-normally ordered characteristic function of the intra-cavity photons produced by a non-degenerate parametric oscillator could be calculated. With the help of the resulting characteristic function, the Q- function which is then used to calculate the entanglement of the intracavity photons using VNE is determined. Moreover, the photon number distribution, the mean photon number, the normalized second order correlation function, the intensity difference, and quadrature variance for the intra-cavity photons produced by a nondegenerate parametric oscillator coupled to a two-mode squeezed vacuum reservoir is determined. It was found that when the squeeze parameter increases the entanglement also increases. These show that the entropy entanglement has a direct relation with squeezing.Keywords:Entanglement, Mean photon number, Parametric down conversion, Q-function

Ethiopian Journal of Education and Sciences•Jul 15, 2019•0 citations
Employing the quantum Hamiltonian describing the interaction of a two-mode light (signal–idler modes) generated by a non-degenerate parametric oscillator (NDPO) with two uncorrelated squeezed vacuum reservoirs (USVR), we derive the master and the Fokker–Planck equations. The corresponding Fokker–Planck equation for the Q-function is then solved employing a propagator method developed by K. Fesseha [J. Math. Phys. 33 2179 (1992)]. Making use of this Q-function, we calculate the quadrature fluctuations of the optical system. From these results we infer that the signal–idler modes are in squeezed states. When the NDPO operates below threshold we show that, for a large squeezing parameter, a squeezing amounting to a noise suppression approaching 100% below the vacuum level in one of the quadratures can be achieved.
A degenerate optical parametric oscillator (DOPO) in the above threshold regime is a prominent source of squeezed field. In this study, a driven DOPO whose pump mode is coupled to a thermal bath while the signal mode is coupled to a squeezed vacuum reservoir is explored to understand the effect of the external squeezed light and the thermal fluctuations on the squeezing properties of both the intracavity and output pump and signal modes. Our findings showed that the injected squeezed vacuum reservoir enables the intracavity squeezing to surpass the maximum squeezing limit of 50% attainable in a DOPO coupled to an ordinary vacuum reservoir. We also found that the maximum squeezing of the output signal mode shifts from resonance to off-resonance in the presence of the injected squeezed vacuum field. Furthermore, the output pump mode exhibits nearly perfect squeezing for a squeezing parameter of r=2. Unlike the output signal mode, the maximum squeezing of the output pump mode occurs at resonance in the presence of the injected squeezed vacuum reservoir. Moreover, a considerable amount of squeezing is observed even in the presence of thermal fluctuations, as they are counterbalanced by the external squeezed light. Notably, relative damping rate between the pump and signal modes is observed to be a parameter that significantly influences squeezing, indicating the importance of optimizing the amount of damping depending on the intended purpose of the DOPO.
We investigate the statistical and quadrature squeezings, as well as the entanglement properties, of a two-mode light generated by non-degenerate parametric oscillations coupled to a two-mode squeezed vacuum reservoir, by employing the solutions of the quantum Langevin equations. It is found that the two-mode light shows the two-mode squeezing and entanglement for all values of the time. Moreover, it is observed that the squeezed vacuum reservoir and the growing amplitude of the pump mode enhance the degrees of two-mode squeezing and entanglement. We have also shown that the amounts of squeezing and entanglement are significant in a region, where the mean photon number is higher, and the photon number correlation is lower.
The von-Neumann entropy (VNE), usually expressed in terms of the density operator, isthe mathematical tool to measure the degree of entanglement of a bi-partite system.Applying the solutions of the quantum Langevin equations, the anti-normally orderedcharacteristic function of the intra-cavity photons produced by a non-degenerateparametric oscillator could be calculated. With the help of the resulting characteristicfunction, the Q- function which is then used to calculate the entanglement of the intra-cavity photons using VNE is determined. Moreover, the photon number distribution, themean photon number, the normalized second order correlation function, the intensitydifference, and quadrature variance for the intra-cavity photons produced by a non-degenerate parametric oscillator coupled to a two-mode squeezed vacuum reservoir isdetermined. It was found that when the squeeze parameter increases the entanglement alsoincreases. These show that the entropy entanglement has a direct relation with squeezing.
We investigate continuous-variable entangling resources on the basis of two-mode squeezing for all operational regimes of a nondegenerate optical parametric oscillator with allowance for quantum noise of an arbitrary level. The results for the quadrature variances of a pair of generated modes are obtained by using the exact steady-state solution of the Fokker-Planck equation for the complex-PPP-representation quasiprobability distribution function. We find a simple expression for the squeezed variances in the near-threshold range and conclude that the maximal two-mode squeezing reaches 50% relative to the level of vacuum fluctuations and is achieved at the pump field intensity close to the generation threshold. The distinction between the degrees of two-mode squeezing for monostable and bistable operational regimes is cleared up.
The effect of squeezing on the degenerate parametric oscillator is studied. It is shown that when the ordinary-vacuum reservoir is replaced by a squeezed-vacuum reservoir, the maximum 50% limit of the second-order squeezing inside the cavity can be crossed. It is also shown that the mean number of photons increases considerably. An exact steady-state solution for the Fokker-Planck equation for the field mode is also presented. The photon distribution for the intracavity field and the higher-order variances have been obtained by using the solution of this equation.
The von-Neumann entropy (VNE), usually expressed in terms of the density operator, is the mathematical tool to measure the degree of entanglement of a bi-partite system. Applying the solutions of the quantum Langevin equations, the anti-normally ordered characteristic function of the intra-cavity photons produced by a non-degenerate parametric oscillator could be calculated. With the help of the resulting characteristic function, the Q- function which is then used to calculate the entanglement of the intracavity photons using VNE is determined. Moreover, the photon number distribution, the mean photon number, the normalized second order correlation function, the intensity difference, and quadrature variance for the intra-cavity photons produced by a nondegenerate parametric oscillator coupled to a two-mode squeezed vacuum reservoir is determined. It was found that when the squeeze parameter increases the entanglement also increases. These show that the entropy entanglement has a direct relation with squeezing.Keywords:Entanglement, Mean photon number, Parametric down conversion, Q-function