| 双光腔耦合下机械振子的基态冷却 |
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| 引用本文： | 刘妮,王建芬,梁九卿.双光腔耦合下机械振子的基态冷却[J].物理学报,2020(6):82-92. |
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| 作者姓名： | 刘妮 王建芬 梁九卿 |
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| 作者单位： | 山西大学理论物理研究所量子光学与光量子器件国家重点实验室 |
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| 基金项目： | 国家自然科学基金(批准号:11772177);山西省青年学者基金(批准号:201701D221001);山西省高等学校科技创新项目(批准号:2019L0069);山西省“1331工程”重点学科建设计划资助的课题~~ |
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| 摘 要： | 机械振子的基态冷却是腔量子光力学中的基本问题之一.所谓的基态冷却就是让机械振子的稳态声子数小于1.本文通过光压涨落谱和稳态声子数研究双光腔光力系统(标准单光腔光力系统中引入第二个光腔,并与第一个光腔直接耦合)的基态冷却.首先得到系统的有效哈密顿量,然后给出朗之万方程和速率方程,最后分别给出空腔和原子腔的光压涨落谱、冷却率和稳态声子数.通过光压涨落谱、冷却率和稳态声子数表达式,重点讨论空腔时机械振子的基态冷却,发现当满足最佳参数条件(机械振子的冷却跃迁速率对应光压涨落谱的最大值,而加热跃迁速率对应光压涨落谱的最小值)时,机械振子可以被冷却到稳态声子数足够少.此外分析:当辅助腔内注入原子系综时,若参数选择恰当可能更利于基态冷却.
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| 关 键 词： | 双光腔 基态冷却 朗之万方程 速率方程 |
Ground-state cooling of mechanical resonator in double optical cavity |
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| Liu Ni,Wang Jian-Fen,Liang Jiu-Qing.Ground-state cooling of mechanical resonator in double optical cavity[J].Acta Physica Sinica,2020(6):82-92. |
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| Authors: | Liu Ni Wang Jian-Fen Liang Jiu-Qing |
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| Affiliation: | (State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Theoretical Physics,Shanxi University,Taiyuan 030006,China) |
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| Abstract: | The ground-state cooling of mechanical resonator is one of the fundamental problems in cavity quantum photomechanics.The so-called ground-state cooling is to make the number of steady-state phonons of the mechanical resonator less than one.In this paper,we first propose an electromagnetically-induced-transparencylike cooling mechanism in a double-cavity optomechanical system to cool a mechanical resonator.In the doubleoptical cavity optomechanical system,the right additional cavity,which is directly coupled to a standard optomechanical system,contains an ultra-cold two-level atomic ensemble.By selecting the optimal parameters to meet the cooling process of the mechanical resonator corresponding to the maximum value of the optical fluctuation spectrum and the heating process of the mechanical resonator corresponding to the minimum value of the optical fluctuation spectrum,the mechanical resonator can be cooled by monitoring the phonon number.We also exert the effects of the atomic additional cavity on the quantum Langevin equations and optical fluctuation spectrum.We find that the atomic double-cavity system may have a better ground-state cooling than the double-cavity in certain parameters.To date,the researchers have proposed a number of theoretical cooling schemes in order to achieve the ground-state cooling of mechanical resonator.As far as we know,the sideband cooling for just a standard optomechanical system is a most famous scheme and the mechanical resonator is coupled to the optical field via radiation pressure force.By the quantum theory of mechanical resonator’s sideband cooling,the optical fluctuation spectrum determines the transition rate of both cooling and heating process of the mechanical resonator.That’s to say,the optical fluctuation spectrum at a mechanical resonator frequency ωm is corresponding to the cooling transition,whereas the optical fluctuation spectrum at-ωm is corresponding to the heating transition.They respectively correspond to anti-Stokes and Stokes effect in physics.Under resolvable sideband conditions,the optical field’s decay rate(the half-width of the single Lorentzian peak of optical fluctuation spectrum)is less than the frequency of the mechanical resonator.So,the ground-state cooling of the mechanical resonator can be obtained by making the maximum and minimum value of the optical fluctuation spectrum respectively correspond to the cooling anti-Stokes process and heating Stokes process.In this paper,we mainly observe the electromagnetically-induced-transparency-like ground-state cooling in a double-cavity optomechanical system with an ensemble of two-level atoms.By adjusting the maximum and minimum value of the optical fluctuation spectrum at the position of ω=ωm and ω=–ωm,the mechanical resonator could be cooled down approximately to the ground state.Even when there exists an ensemble of twolevel atoms in the right additional cavity,the mechanical resonator can be better cooled than just a cavity.These results may be conducive to the ground-state cooling of the mechanical resonator in the future experiment. |
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| Keywords: | double-optical cavity ground state cooling Langevin equation rate equation |
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