共查询到20条相似文献,搜索用时 15 毫秒
1.
Generation of strong stationary optical and mechanical squeezing is proposed for the linear‐and‐quadratic optomechanical system, where two cavity modes induce linear and quadratic optomechanical couplings, respectively. Through the linearization treatment, linearized coupling between cavity mode and mechanical mode and the mechanical parametric amplification process are achievable and controllable by independent driving lasers. Optical and mechanical squeezing are generated following different mechanisms. Optical squeezing works in the strong coupling regime, and mechanical amplification would push the system close to instability threshold, which could deeply improve ponderomotive squeezing even significantly beyond the 3 dB squeezing limit. Mechanical squeezing is generated based on the reservoir engineering method, where parametric amplification induces the squeezing transformation of mechanical mode; and linearized coupling, which operates in the red‐sideband and weak coupling limits, induces the ground‐state cooling of transformed mechanical mode. Finally, the original mechanical mode would be squeezed, which could also exceed 3 dB limit. 相似文献
2.
Measurement of the position of an oscillator by means of a Fabry-Perot resonator with one moving mirror (oscillator mass) pumped by a laser in the regime of strongly detuned pumping is analyzed. Compensation of fluctuational back action in the reflected wave is demonstrated. However, this does not allow overcoming the standard quantum limit due to the dynamic back action. Additionally, the possibility of detecting mechanical squeezing under parametric action on a mechanical oscillator is analyzed. 相似文献
3.
In this study, we investigate a hybrid system consisting of an atomic ensemble trapped inside a dissipative optomechanical cavity assisted with perturbative oscillator-qubit coupling. Such a system is generally very suitable for generating stationary squeezing of the mirror motion in the long-time limit under the unresolved sideband regime. Based on the master equation and covariance matrix approaches, we discuss in detail the respective squeezing effects. We also determine that in both approaches, simplifying the system dynamics with adiabatic elimination of the highly dissipative cavity mode is very effective. In the master equation approach, we find that the squeezing is a resulting effect of the cooling process and is robust against thermal fluctuations of the mechanical mode. In the covariance matrix approach, we can approximately obtain the analytical result of the steady-state mechanical position variance from the reduced dynamical equation. Finally, we compare the two approaches and observe that they are completely equivalent for the stationary dynamics. Moreover, the scheme may be useful for possible ultraprecise quantum measurement that involves mechanical squeezing. 相似文献
4.
Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the quantum information theory, we have investigated the
entropy squeezing of a moving two-level atom interacting with the
coherent field via the quantum mechanical channel of the two-photon
process. The results are compared with those of atomic squeezing
based on the Heisenberg uncertainty relation. The influences of the
atomic motion and field-mode structure parameter on the atomic
entropy squeezing and on the control of noise of the quantum
mechanical channel via the two-photon process are examined. Our
results show that the squeezed period, duration of optimal entropy
squeezing of a two-level atom and the noise of the quantum mechanical
channel can be controlled by appropriately choosing the atomic motion
and the field-mode structure parameter, respectively. The quantum
mechanical channel of two-photon process is an ideal channel for
quantum information (atomic quantum state) transmission. Quantum
information entropy is a remarkably accurate measure of the atomic
squeezing. 相似文献
5.
In the conventional scheme of generating strong mechanical squeezing by the joint effect between mechanical parametric amplification and sideband cooling, the resolved sideband condition is required so as to overcome the quantum backaction heating. In the unresolved sideband regime, to suppress the quantum backaction, a χ(2) nonlinear medium is introduced to the cavity. The result shows that the quantum backaction heating effect caused by unwanted counter-rotating term can be completely removed. Hence, the strong mechanical squeezing can be obtained even for the system far from the resolved-sideband regime. 相似文献
6.
7.
Ast S Samblowski A Mehmet M Steinlechner S Eberle T Schnabel R 《Optics letters》2012,37(12):2367-2369
Squeezed states can be employed for entanglement-based continuous-variable quantum key distribution, where the secure key rate is proportional to the bandwidth of the squeezing. We produced a nonclassical cw laser field at the telecommunication wavelength of 1550 nm, which showed squeezing over a bandwidth of more than 2 GHz. The experimental setup used parametric downconversion via a periodically poled potassium titanyl phosphate crystal. We did not use any resonant enhancement for the fundamental wavelength, which should in principle allow a production of squeezed light over the full phase-matching bandwidth of several nanometers. We measured the squeezing to be up to 0.3 dB below the vacuum noise from 50 MHz to 2 GHz limited by the measuring bandwidth of the homodyne detector. The squeezing strength was possibly limited by thermal lensing inside the nonlinear crystal. 相似文献
8.
低频信号测量在引力波探测、生物成像及磁场测量等方面具有重要的应用价值.本文利用非简并光学参量放大器获得了低频压缩态光场,在频率19 kHz处直接测到的压缩度为(7.1±0.1)dB;将产生的正交位相压缩态光场注入到马赫-曾德尔干涉仪中,实现了超越散粒噪声极限(3.0±0.4)dB的声频相位信号的测量.本实验的开展为低频压缩光的产生及基于低频压缩光的声频信号测量提供了一定技术支撑,并且此技术有望扩展到磁场、空间小位移等其他物理量的量子精密测量方案中. 相似文献
9.
We report the first measurement of the quantum phase-difference noise of an ultrastable nondegenerate optical parametric oscillator that emits twin beams classically phase locked at exact frequency degeneracy. The measurement illustrates the property of a lossless balanced beam splitter to convert number-difference squeezing into phase-difference squeezing, and thus provides indirect evidence for Heisenberg-limited interferometry using twin beams. This experiment is a generalization of the Hong-Ou-Mandel interference effect for continuous variables and constitutes a milestone towards continuous-variable entanglement of bright, ultrastable nondegenerate beams. 相似文献
10.
M. Sebawe Abdalla 《Physica A》1994,210(3-4):461-475
From the quantum mechanics and the quantum optics point of view the problem of the time-dependent Hamiltonian which describes the degenerate parametric amplifier is presented. Under a certain integrability condition the solution of the Heisenberg equations of motion is given. The wave function for both the Schrödinger picture and quasi-coherent states, as well as the Green's function is obtained. The Glauber second order correlation function, and the squeezing and higher order squeezing is examined. The quasi-probability distribution function is also considered. 相似文献
11.
12.
A scheme for nonreciprocal mechanical squeezing (NMS) based on the three‐mode optomechanical interaction is proposed. In this scheme, a mechanical mode couples to a spinning whispering‐gallery‐cavity (WGC) mode and to an optical mode. An external laser is coupled into and thus drives the WGC via a waveguide. Mechanical squeezing results from the joint effect of the mechanical intrinsic nonlinearity and the quadratic optomechanical coupling, which, in the presence of strong thermal noise, is still considerable, while the nonreciprocity originates from the optical Sagnac effect. There are two NMS areas in the parametric space, one works for the laser driving from the left of the waveguide and another, from the right. For a given spinning speed of the WGC, the squeezing values in these two areas are equal if the corresponding detunings of the WGC differ from each other by two‐times of the Sagnac–Fizeau shift. At the red‐detuning resonance, the analytical results for the mechanical squeezing and cooling are obtained. The NMS scheme is robust to the thermal noise of the mechanical environment. 相似文献
13.
Squeezing of the intracavity field in a degenerate parametric oscillator is calculated above threshold neglecting pump depletion. Arbitrary squeezing is in principle obtainable. We conclude that above threshold squeezing in the steady-state parametric oscillator is limited primarily by pump depletion rather than degradation by vacuum fluctuations at the mirrors. The squeezing predicted by the present calculation should be observable in an oscillator operated in a transient or pulsed mode 相似文献
14.
The Squeezing and sub-poissonian photon statistics of an optical field are a purely quantum mechanical phenomenon and has
been accepted as means of achieving noise below the quantum shot-noise limit. The effect of higher-order squeezing and sub-poissonian
nature of an optical field in coherent anti-Stokes Raman scattering (CARS) and coherent anti-Stokes hyper Raman scattering
(CAHRS) are investigated under short-time approximation. The coupled Heisenberg equations of motion involving real and imaginary
parts of the quadrature operators are established and solved under short-time scale. The dependence of squeezing on the number
of photons is also investigated. It is also shown that higher-order squeezing allows a much larger fractional noise reduction
than lower-order squeezing. The occurrence of amplitude squeezing effects of the radiation field in the fundamental mode is
investigated in both the processes. The present work shows that squeezing is greater in CAHRS than the corresponding squeezing
in CARS. It is also shown that squeezing is greater in stimulated process than corresponding squeezing in spontaneous interaction.
The conditions for obtaining maximum and minimum squeezing are obtained. The photon statistics of the pump mode in the processes
has also been investigated and found to be sub-poissonian in nature. 相似文献
15.
The solution of the time-dependent Fokker--Planck equation of non-degenerate optical parametric amplification and its application to the optimum realization of EPR paradox
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, the solution of the time-dependent Fokker--Planck
equation of non-degenerate optical parametric amplification is
used to deduce the condition demonstrating the
Einstein--Podolsky--Rosen (EPR) paradox. The analytics and
numerical calculation show the influence of pump depletion on
the error in the measurement of continuous variables. The
optimum realization of EPR paradox can be achieved by adjusting
the parameter of squeezing. This result is of practical
importance when the realistic experimental conditions are taken
into consideration. 相似文献
16.
Spatial quantum optics and quantum information based on the high order transverse mode are of importance for the super-resolution measurement beyond the quantum noise level. We demonstrated experimentally the transverse plane TEM01 Hermite-Gauss quantum squeezing. The squeezed TEM01 mode is generated in a degenerate optical parametric amplifier with the nonlinear crystal of periodically poled KTiOPO4. The level of 2.2-dB squeezing is measured using a spatial balance homodyne detection system. 相似文献
17.
基于PPKTP晶体的阈值以下光学参量振荡(OPO)过程,制备了共振于铷原子D1线795 nm的压缩真空态光场,研究了分析频率处于千赫兹范围的主要噪声来源,特别是795 nm激光及其二次谐波397.5 nm激光在晶体内吸收引起的非线性损耗增加和系统热不稳定的问题(397.5 nm激光处于PPKTP晶体透光范围边缘,具有高于其他波长数倍的吸收系数).以795 nm和1064 nm为例,分析了非线性损耗及晶体内热效应对压缩度的影响.受限于以上因素,795 nm压缩光很难得到1064 nm波段同样的压缩度.探测系统中的噪声耦合则限制了压缩频带.实验上对分析频率为千赫兹的经典噪声进行了有效控制,通过使用真空注入的OPO、垂直偏振及反向传输的腔长锁定光、低噪声的平衡零拍探测器、高稳定度的实验系统及量子噪声锁定等方法,最终在2.6—100 kHz的分析频段得到了约2.8 dB的795 nm压缩真空.该压缩光可用作磁场测量系统的探测光以提高测量灵敏度. 相似文献
18.
The cavity magnomechanical system has become a promising platform for preparing macroscopic quantum states. In this work, a scheme for generating the steady-state quadrature squeezing of the magnon and phonon modes in a cavity magnomechanical system is presented. This scheme uses a degenerate microwave parametric amplifier (PA) inside the microwave cavity. It is found that the squeezing of the cavity mode produced by the PA can be transferred to the magnon mode due to the cavity-magnon beamsplitter-like interaction, and the squeezing of the magnon mode can be further transferred to the phonon mode due to the magnon-phonon beamsplitter-like interaction induced by driving the magnon mode with a red-detuned microwave field. The effects of the parametric gain and phase of the PA, the magnon-cavity coupling strength, the power of the magnon drive, and the temperature of the environment on the squeezing of the magnon and phonon modes have been evaluated. The results show that the squeezing of the magnon and phonon modes is robust against the temperature of the environment. 相似文献
19.
The aim of this paper is to study the squeezing and statistical properties of the light produced by a degenerate three-level laser whose cavity contains a degenerate parametric amplifier. In this quantum optical system the top and bottom levels of the three-level atoms injected into the laser cavity are coupled by the pump mode emerging from the parametric amplifier. For a linear gain coefficient of 100 and for a cavity damping constant of 0.8, the maximum intracavity squeezing is found at steady state and at threshold to be 93%. 相似文献
20.
《中国光学快报(英文版)》2016,(6)
Nonclassical optical frequency combs find tremendous utility in quantum information and high-precision quantum measurement. The characteristics of a type-I synchronously pumped optical parametric oscillator with the TEM_(01) transverse mode below threshold are investigated and a squeezing of 0.7 dB for an optical frequency comb squeezed light field with the TEM_(01) transverse mode is obtained under the pump power of 130 m W. This work has a promising application in three-dimensional space-time measurement. 相似文献