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

Generation and homodyne detection of continuous-variable entangled optical beams with a large wavelength difference

Xiaomin Guo, Changde Xie, Yongmin Li

Published Aug 2, 2011• 14 citations
Publisher

Abstract

We present a scheme for generating and homodyne detecting of continuous-variable entanglement of bright optical beams with a large wavelength difference by utilizing an optical parametric oscillator (OPO) and an optical parametric amplifier (OPA) simultaneously. Entangled optical beams at 0.8 and 1.5 \ensuremath{\mu}m are generated from the OPA; the seed beams injected in the OPA as well as the local oscillators at the two wavelengths needed for homodyne detection are provided by the OPO. The entangler is a ring resonator involving a second-order nonlinear crystal that is pumped from two opposite directions. In one direction the pump power is above the oscillation threshold and the optical nonlinear resonator operates as an OPO. In the other direction the pump power is below the threshold and it operates as a phase-sensitive frequency nondegenerate optical parametric amplifier. Our scheme combines the advantages of both OPO and OPA quantum optical devices and opens another avenue for preparation and homodyne detection of high quality bright entangled light with a large wavelength difference.

DOI
10.1103/physreva.84.020301

Related papers

Robust generation of bright two-color entangled optical beams from a phase-insensitive optical parametric amplifier

Xiaomin Guo, Jun-Jun Zhao, Yongmin Li

Bright two-color continuous variable (CV) entangled optical beams at 0.8 and 1.5 μm are generated by utilizing a phase-insensitive optical parametric amplifier with only 1.5 μm signal field injected. Without locking the relative phase between the signal and pump fields, the amplitude quadrature difference squeezing of 3.30 dB and phase quadrature sum squeezing of 3.35 dB are observed, which satisfy the entanglement criterion. The demonstrated scheme here eliminates the necessity of precise phase control between the signal and pump fields and enables robust generation of two-color CV entangled states.

Applied Physics Letters•Feb 27, 2012•11 citations

Efficient generation of CV entanglement by triply resonant non-degenerate OPA

A. Porzio, Virginia D’Auria, Stefano Fornaro +3 more

CV entangled CW bright beams are experimentally generated by a Non-degenerate "triply resonant" Optical Parametric Amplifier (NOPA) based on PPKTP type-II crystal below threshold. Operating the OPA at frequency degeneracy makes the down-converted entangled beams able to be optically manipulated for generating different combination of the entangled system. Particular care has been required by the triply resonance condition essential to obtain a suffcient degree of entanglement. The triply resonance condition is pursued by combining temperature phase-matching and crystal tilting in an optical cavity so to optimize the triple resonance condition acting on different independent parameters. Exploiting the dependence of the bipartite system covariance matrix on different combination of this continuous variable two-mode states it can be directly measured using a single homodyne detector and few linear optical elements. The system is actually operating at the University of Napoli-Quantum Optics Laboratory. Preliminary measurements show that CV entanglement is present at the OPO output. This source of CV entanglement can be used for quantum communication purposes. The technical tricks herein implemented are interesting also for realizing triply resonant CW OPOs whose spectral properties and conversion efficiencies are better compared to single and double resonant devices. The quality of entanglement is also improved thanks to the use of a single cavity instead of dual cavities often employed in triply resonant devices. The measurement method can be applied to generic bipartite states made of frequency degenerate but orthogonally polarized modes.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 4, 2007•0 citations

Experimental continuous-variable entanglement of phase-locked bright optical beams

Jietai Jing, Sheng Feng, Russell Bloomer +1 more

We observed continuous-variable entanglement between two bright beams emitted above threshold by a phase-difference-locked ultrastable optical parametric oscillator. The amplitude-difference squeezing is -3 dB and the phase-sum one is -1.35 dB. The beams are classically phase-locked at a frequency difference of 161.8273240(5) MHz, continuously tunable by the OPO crystal temperature. Such unprecedented frequency-difference stability paves the way for implementing quantum frequency multiplexing and CV quantum information in the frequency domain.

•Apr 18, 2006•4 citations

Continuous variable quantum entanglement at 1.34 m

马亚云 Ma Yayun, Feng Jin-Xia, Wan Zhen-Ju +2 more

Continuous variable (CV) quantum entanglement is a fundamental resource of CV quantum communication and quantum computation. It is useful in a wide variety of applications, including quantum teleportation, quantum dense coding, quantum key distribution, and high-precision quantum measurement. In this paper, we generate CV quantum entanglement at a telecommunication wavelength of 1342 nm by using a nondegenerate optical parametric amplifier (NOPA) with a type-Ⅱ periodically poled KTiOPO4 (PPKTP) crystal. A home-made continuous-wave single-frequency dual-wavelength (671 nm and 1342 nm) Nd:YVO4/LiB3O5 laser is achieved with output powers of 1.5 W (671 nm) and 1.3 W (1342 nm). Then a mode cleaner (MC1) with a fineness of 400 and linewidth of 0.75 MHz and a mode cleaner MC2 with a fineness of 400 and linewidth of 0.75 MHz are used to filter the noises of laser at 1342 nm and 671 nm, respectively. By using MCs, the intensity noise of laser reaches a shot noise level (SNL) for analysis frequencies higher than 1.0 MHz, and the phase noise of laser reaches an SNL for analysis frequencies higher than 1.3 MHz. Utilizing this kind of low noise single-frequency 671 nm laser as a pump, a doubly-resonant optical parametric oscillator with a threshold of 325 mW is realised. When the low noise single-frequency 1342 nm laser is injected as a signal and the relative phase between the pump and injected signal is locked to , the NOPA is operated at deamplification. After optimizing the temperature of the type-Ⅱ PPKTP crystal and at a pump power of 260 mW, Einstein-Podolsky-Rosen (EPR)-entangled beams with quantum correlation of 3.0 dB for both the amplitude and phase quadratures are experimentally generated. The strength of EPR-entangled beams is relatively low. It is maybe due to the low nonlinear conversion efficiency and large absorption of the type-Ⅱ PPKTP crystal at 671 nm and 1342 nm. The generated CV quantum entanglement at 1.34 m has lower transmission loss and smaller phase diffusion effect in a silica fiber. The research contributes to a high quality quantum source for the CV quantum communication based on existing telecommunication fiber networks.

Acta Physica Sinica•Jan 1, 2017•6 citations

Multicolor Continuous-Variable Entanglement

A. S. Coelho, F. A. S. Barbosa, K. N. Cassemiro +3 more

Direct generation of tripartite entanglement between pump, signal, and idler beams of an above-threshold optical parametric oscillator was implemented. All three bright beams of light have different wavelengths. Partial-loss disentanglement was also observed.

Latin America Optics and Photonics Conference•Jan 1, 2010•0 citations

Bright three-color entangled state produced by cascaded optical parametric oscillators

Aihong Tan, Changde Xie, Kunchi Peng

We propose a generation system of continuous-variable (CV) three-color entangled state of bright optical beams based on two cascaded standard nondegenerate optical parametric oscillators (NOPOs) above the threshold. One of signal and idler beams produced by the first NOPO is used for the pump light of the second NOPO. The three-color entanglement among signal and idler beams produced by the second NOPO and the retained another beam of the first NOPO is theoretically demonstrated. The symplectic eigenvalues of the partial transposition covariance matrix of the generated optical entangled state are numerically calculated in terms of experimentally reachable system parameters. The optimal operation conditions of the cascaded NOPOs system for obtaining high entanglement are found. The calculated results explicitly demonstrate that the OPO action can transfer entanglement. Due to that the cavity parameters and the nonlinear crystals of the two NOPOs can be freely chosen, the flexibility of the proposed protocol is relatively good and the system can be also extended to prepare entangled states with more parts easily.

Physical Review A•Jan 17, 2012•16 citations
We present a scheme for generating and homodyne detecting of continuous-variable entanglement of bright optical beams with a large wavelength difference by utilizing an optical parametric oscillator (OPO) and an optical parametric amplifier (OPA) simultaneously. Entangled optical beams at 0.8 and 1.5 \ensuremath{\mu}m are generated from the OPA; the seed beams injected in the OPA as well as the local oscillators at the two wavelengths needed for homodyne detection are provided by the OPO. The entangler is a ring resonator involving a second-order nonlinear crystal that is pumped from two opposite directions. In one direction the pump power is above the oscillation threshold and the optical nonlinear resonator operates as an OPO. In the other direction the pump power is below the threshold and it operates as a phase-sensitive frequency nondegenerate optical parametric amplifier. Our scheme combines the advantages of both OPO and OPA quantum optical devices and opens another avenue for preparation and homodyne detection of high quality bright entangled light with a large wavelength difference.
Bright two-color continuous variable (CV) entangled optical beams at 0.8 and 1.5 μm are generated by utilizing a phase-insensitive optical parametric amplifier with only 1.5 μm signal field injected. Without locking the relative phase between the signal and pump fields, the amplitude quadrature difference squeezing of 3.30 dB and phase quadrature sum squeezing of 3.35 dB are observed, which satisfy the entanglement criterion. The demonstrated scheme here eliminates the necessity of precise phase control between the signal and pump fields and enables robust generation of two-color CV entangled states.
CV entangled CW bright beams are experimentally generated by a Non-degenerate "triply resonant" Optical Parametric Amplifier (NOPA) based on PPKTP type-II crystal below threshold. Operating the OPA at frequency degeneracy makes the down-converted entangled beams able to be optically manipulated for generating different combination of the entangled system. Particular care has been required by the triply resonance condition essential to obtain a suffcient degree of entanglement. The triply resonance condition is pursued by combining temperature phase-matching and crystal tilting in an optical cavity so to optimize the triple resonance condition acting on different independent parameters. Exploiting the dependence of the bipartite system covariance matrix on different combination of this continuous variable two-mode states it can be directly measured using a single homodyne detector and few linear optical elements. The system is actually operating at the University of Napoli-Quantum Optics Laboratory. Preliminary measurements show that CV entanglement is present at the OPO output. This source of CV entanglement can be used for quantum communication purposes. The technical tricks herein implemented are interesting also for realizing triply resonant CW OPOs whose spectral properties and conversion efficiencies are better compared to single and double resonant devices. The quality of entanglement is also improved thanks to the use of a single cavity instead of dual cavities often employed in triply resonant devices. The measurement method can be applied to generic bipartite states made of frequency degenerate but orthogonally polarized modes.
We observed continuous-variable entanglement between two bright beams emitted above threshold by a phase-difference-locked ultrastable optical parametric oscillator. The amplitude-difference squeezing is -3 dB and the phase-sum one is -1.35 dB. The beams are classically phase-locked at a frequency difference of 161.8273240(5) MHz, continuously tunable by the OPO crystal temperature. Such unprecedented frequency-difference stability paves the way for implementing quantum frequency multiplexing and CV quantum information in the frequency domain.
Continuous variable (CV) quantum entanglement is a fundamental resource of CV quantum communication and quantum computation. It is useful in a wide variety of applications, including quantum teleportation, quantum dense coding, quantum key distribution, and high-precision quantum measurement. In this paper, we generate CV quantum entanglement at a telecommunication wavelength of 1342 nm by using a nondegenerate optical parametric amplifier (NOPA) with a type-Ⅱ periodically poled KTiOPO4 (PPKTP) crystal. A home-made continuous-wave single-frequency dual-wavelength (671 nm and 1342 nm) Nd:YVO4/LiB3O5 laser is achieved with output powers of 1.5 W (671 nm) and 1.3 W (1342 nm). Then a mode cleaner (MC1) with a fineness of 400 and linewidth of 0.75 MHz and a mode cleaner MC2 with a fineness of 400 and linewidth of 0.75 MHz are used to filter the noises of laser at 1342 nm and 671 nm, respectively. By using MCs, the intensity noise of laser reaches a shot noise level (SNL) for analysis frequencies higher than 1.0 MHz, and the phase noise of laser reaches an SNL for analysis frequencies higher than 1.3 MHz. Utilizing this kind of low noise single-frequency 671 nm laser as a pump, a doubly-resonant optical parametric oscillator with a threshold of 325 mW is realised. When the low noise single-frequency 1342 nm laser is injected as a signal and the relative phase between the pump and injected signal is locked to , the NOPA is operated at deamplification. After optimizing the temperature of the type-Ⅱ PPKTP crystal and at a pump power of 260 mW, Einstein-Podolsky-Rosen (EPR)-entangled beams with quantum correlation of 3.0 dB for both the amplitude and phase quadratures are experimentally generated. The strength of EPR-entangled beams is relatively low. It is maybe due to the low nonlinear conversion efficiency and large absorption of the type-Ⅱ PPKTP crystal at 671 nm and 1342 nm. The generated CV quantum entanglement at 1.34 m has lower transmission loss and smaller phase diffusion effect in a silica fiber. The research contributes to a high quality quantum source for the CV quantum communication based on existing telecommunication fiber networks.
We propose a generation system of continuous-variable (CV) three-color entangled state of bright optical beams based on two cascaded standard nondegenerate optical parametric oscillators (NOPOs) above the threshold. One of signal and idler beams produced by the first NOPO is used for the pump light of the second NOPO. The three-color entanglement among signal and idler beams produced by the second NOPO and the retained another beam of the first NOPO is theoretically demonstrated. The symplectic eigenvalues of the partial transposition covariance matrix of the generated optical entangled state are numerically calculated in terms of experimentally reachable system parameters. The optimal operation conditions of the cascaded NOPOs system for obtaining high entanglement are found. The calculated results explicitly demonstrate that the OPO action can transfer entanglement. Due to that the cavity parameters and the nonlinear crystals of the two NOPOs can be freely chosen, the flexibility of the proposed protocol is relatively good and the system can be also extended to prepare entangled states with more parts easily.