混合腔光力系统的双光子散射

混合腔光力系统同时包含一次和二次光力相互作用。本文研究了混合腔光力系统中的双光子散射问题。在Wigner-Weisskopf框架下,通过求解散射过程,获得了混合腔光力系统散射态的解析表达式,揭示了双光子散射的4个物理过程：1)双光子均被直接反射,不进入腔中;2)一个光子被直接反射,另一个光子入射进腔中;3)两个光子按次序先后入射进腔中,但腔中最多只有一个光子;4)两个光子均入射进腔中。通过分析双光子散射谱,发现在该散射过程中可以产生双光子频率反关联,并且发现了混合腔光力系统中的参数与双光子散射谱特性之间的联系。该研究不仅提供了一种产生关联光子对的散射方法,而且提出了一种表征光力系统参数的光谱方法。     

腔光力系统制备微波非经典态研究进展

腔光力系统作为一种新型的混合量子系统,因其超强耦合度、低温超导条件下极低的噪声、较长的相干时间等优势而成为被广受关注的量子实验平台.本文简要介绍腔光力学及腔光力系统基本原理,对常见腔光力系统进行分类,详细介绍利用广义腔光力系统进行微波非经典量子态制备的相关进展,对其性能优势和待解决问题进行分析,最后总结相关应用场景并对未来的潜在应用领域进行了展望.     

双拉盖尔-高斯腔光力系统中的腔内压缩冷却研究

机械振子的冷却是腔光力学研究的重要方向之一。计算光力噪声谱和稳态的最终声子数,对基于耦合光学参量放大器（OPA）的双拉盖尔-高斯腔光力系统中的腔内压缩冷却问题进行研究。在弱耦合条件下,利用微扰近似理论方法得出系统的光力噪声谱,基于费米黄金法则的理论计算出稳态下的最终声子数的解析表达式。利用入射泵浦光驱动腔场内耦合的OPA,使腔场内形成强烈的非线性压缩效应,量子反作用加热过程得到有效抑制,系统净冷却率得到显著提高。此外,讨论了其他系统参数对机械振子冷却的影响。最后研究了系统的稳态声子数,声子数可以在较大参数范围内小于1。该方案能有效地降低机械振子的冷却极限。     

多模光力系统中的非传统声子阻塞

本文提出在多模光力系统中实现声子阻塞.多模光力系统由一个机械模和两个光学模组成.研究发现,当光学模与机械模同时受到外加驱动场作用时,即使在弱光力耦合条件下也可以实现声子阻塞效应,即非传统声子阻塞效应;给出了非传统声子阻塞效应出现的最佳条件.另外,发现通过调节外加驱动场间强度的比值和相位差可以控制声子的统计性质,这为实现可控的单声子源提供了一个有效方法.最后,讨论了热声子对非传统声子阻塞的不利影响,发现适当提高驱动场强度有利于观测非传统声子阻塞效应.     

回音壁微腔光力系统的相干控制与完全相干透射

本文研究了两侧同时输入的回音壁模谐振双微腔光力系统中电磁诱导透明的相干调控.通过改变双微腔两侧探测场的强度比值及相位差,可以有效控制电磁诱导透明窗口的宽度和深度,对探测场的吸收和色散等性质实施显著的影响,并且能够在特殊频率处产生关于探测场的完全相干透射现象.     

双腔光力学系统中输出光场纠缠特性的研究

腔光力学系统中的光辐射压力可以使系统中的各个子系统之间产生量子纠缠,最近在腔光力学系统中的量子纠缠引起了人们广泛的关注.本文研究了双腔光力系统中关于输出光场之间纠缠的性质,发现:此系统中力学振子的弛豫速率和滤波器带宽以及非相等耦合对输出光场之间纠缠的大小有着非常显著的影响,特别是在相等耦合条件下,输出光场中心频率与光腔本征频率近共振时,滤波器带宽对输出光场纠缠有着显著的抑制作用;但是如果采用非相等耦合,则可以有效抵制滤波器带宽对纠缠的抑制作用,使输出光场纠缠得到大幅提高.研究结果可应用在光力耦合系统中实现量子态转换、量子隐形传态等量子信息处理过程.     

光腔中薄膜振子与电磁场耦合关系的数值解

文章以光腔中有两个薄膜振子的情况为例,介绍了计算薄膜振子与电磁场耦合关系的基本原理和数值方法.利用该方法可以求出薄膜振子在腔内任意位置处与电磁场的耦合关系.     

色散吸收非对称介质光腔中光场的量子理论

利用格林函数方法对色散吸收介质中的电磁场量子化,研究了由色散吸收介质构成的非对称介质光腔中光场的量子理论,并分析了非对称性对光腔量子性质、工作性能等的影响.     

利用腔电光力系统提高罗兰C授时能力研究

罗兰C系统受原子钟以及经典无线电信号测量精度的影响,难以为用户提供高精度授时.提出了一种基于杂化微波-光纠缠的罗兰C系统授时方案,通过腔电光力转换器制备纠缠微波-光信号,并利用纠缠信号的二阶相干函数得到信号传播时间,根据授时时序关系修正用户本地钟时刻并完成授时.仿真分析了腔电光力转换器的参数对授时精度的影响.所提方案在理论上实现了对罗兰C系统授时精度的提高,在抗压制干扰、欺骗干扰等方面都具有一定优势.     

耦合腔高频特性的单腔模型研究与应用

在耦合腔结构的高频特性模拟中,基于准周期边界条件法建立的双腔模型,由于两端电场的边界条件完全相同,导致了伪解的出现。本文建立了单腔仿真模型,消除了伪解存在的边界条件,避免伪解的出现。在保证求解精度的基础上,网格数目减少了 62%,总计算时间缩小了 56%,一次性生成色散曲线和耦合阻抗曲线,提高了色散和耦合阻抗的数据处理效率,为高频结构参数优化提供了更有效的途径。采用单腔仿真模型,模拟分析了各结构尺寸对高频特性的影响。     

Optomechanical sensing with on-chip microcavities

The coupling between optical and mechanical degrees of freedom has been of broad interest for a long time. However, it is only until recently, with the rapid development of optical mierocavity research, that we are able to manipulate and utilize this coupling process. When a high Q microeavity couples to a mechanical resonator, they can consolidate into an optomeehanieal system. Benefitting from the unique characteristics offered by optomeehanical coupling, this hybrid system has become a promising platform for ultrasensitive sensors to detect displacement, mass, force and acceleration. In this review, we introduce the basic physical concepts of cavity optomechanies, and describe some of the most typical experimental cavity optomechanical systems for sensing applications. Finally, we discuss the noise arising from various sources and show the potentiality of optomechanical sensing towards quantum-noise-limited detection.     

Probe Response of an Optomechanical System with Optomechanical Coupling Modulated Periodically

In this study, the probe response of a cavity optomechanical system with periodic modulation of the optomechanical coupling is investigated. The modulation arises from the beat effect between two external coherent driving lights, with the beat frequency matching the modulation frequency. The transmission coefficient is derived for the probe field and significant amplification, rather than absorption in the conventional optomechanically induced transparency schemes, is observed near the transparent point when the modulation is introduced. In addition, the coupling modulation can also enhance the slow light effect.     

Perfect Optical Nonreciprocity with Mechanical Driving in a Three-Mode Optomechanical System *

Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology. Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanical driving.The scheme relies on the interference between optomechanical interaction and mechanical driving. We find perfect optical nonreciprocity can be achieved even though nonreciprocal phase difference is zero if we drive the system by a mechanical driving with a nonzero phase. We obtain the essential conditions for perfectoptical nonreciprocity and analyze properties of the optical nonreciprocal transmission. These results can be used to control optical transmission in quantum information processing.      

Review of cavity optomechanical cooling

Quantum manipulation of macroscopic mechanical systems is of great interest in both fundamental physics and ap- plications ranging from high-precision metrology to quantum information processing. For these purposes, a crucial step is to cool the mechanical system to its quantum ground state. In this review, we focus on the cavity optomechanical cooling, which exploits the cavity enhanced interaction between optical field and mechanical motion to reduce the thermal noise. Recent remarkable theoretical and experimental efforts in this field have taken a major step forward in preparing the mo- tional quantum ground state of mesoscopic mechanical systems. This review first describes the quantum theory of cavity optomechanical cooling, including quantum noise approach and covariance approach; then, the up-to-date experimental progresses are introduced. Finally, new cooling approaches are discussed along the directions of cooling in the strong coupling regime and cooling beyond the resolved sideband limit.     

Generation of Schrödinger Cat States in a Hybrid Cavity Optomechanical System

We present an alternative scheme to achieve Schrödinger cat states in a strong coupling hybrid cavity optomechanical system. Under the single-photon strong-coupling regime, the interaction between the atom–cavity–oscillator system can induce the mesoscopic mechanical oscillator to Schrödinger cat states. Comparing to previous schemes, the proposed proposal consider the second order approximation on the Lamb–Dicke parameter, which is more universal in the experiment. Numerical simulations confirm the validity of our derivation.     

Generalized Rotating-Wave Approximation for the Quantum Rabi Model with Optomechanical Interaction

The spectrum of energy and eigenstates of an hybrid cavity optomechanical system, where a cavity field mode interacts with a mechanical mode of a vibrating end mirror via radiation pressure and with a two level atom via electric dipole interaction are investigated. In the spirit of approximations developed for the quantum Rabi model beyond rotating-wave approximation (RWA), the so-called generalized RWA (GRWA) to diagonalize the tripartite Hamiltonian for arbitrary large couplings is implemented. Notably, the GRWA approach still allows to rewrite the hybrid Hamiltonian in a bipartite form, like a Rabi model with dressed atom-field states (polaritons) coupled to mechanical modes through reparametrized coupling strength and Rabi frequency. A more accurate energy spectrum for a wide range of values of the atom-photon and photon–phonon couplings, when compared to the RWA results is found. The fidelity between the numerical eigenstates and its approximated counterparts is also calculated. The degree of polariton-phonon entanglement of the eigenstates presents a non-monotonic behavior as the atom-photon coupling varies, in contrast to the characteristic monotonic increase in the RWA treatment.     

Electromagnetically induced transparency in a three-mode optomechanical system

We study a three-mode double-cavity optomechanical system in which an oscillating membrane of perfect reflection is inserted between two fixed mirrors of partial transmission. We find that electromagnetically induced transparency （EIT） can be realized and controlled in this optomechanical system by adjusting the relative intensity and the relative phase between left-hand and right-hand input （probe and coupling） fields. In particular, one perfect EIT window is seen to occur when the two probe fields are exactly out of phase and the EIT window＇s width is very sensitive to the relative intensity of two coupling fields. Our numerical findings may be extended to achieve optomechanical storage and switching schemes applicable in quantum information processing.     

Cavity optomechanics with cold atomic gas

We present a tutorial review on the topics related to current development in cavity optomechanics, with special emphasis on cavity optomechanical effects with ultracold gases, Bose-Einstein condensates, and spinor Bose-Einstein condensates. Topics including the quantum model and nonlinearity of the cavity optomechanics, the principles of optomechanical cooling, radiation-pressure-induced nonlinear states, the chaotic dynamics in a condensate-mirror-hybrid optomechanical setup, and the spin-mixing dynamics controlled by optical cavities are covered.     

扇形腔旭日型磁控管结构的理论分析与数字模拟

利用场分析法推导了扇形腔旭日型磁控管的色散关系, 通过CST模拟软件验证了理论推导的正确性, 分析了扇形腔旭日型磁控管的各项结构参数对π 模截止频率和模式分隔度的影响. 研究表明: 色散关系的理论值与模拟值之间的最大相对误差不到3%, π 模截止频率的理论值与模拟值之间的最大相对误差不到1%; π 模截止频率f_πc与阴极半径R_c, 阳极半径R_a, 大腔张角2θ₁成正比关系, 与小腔半径R_d0, 大腔半径R_d1, 小腔张角2θ₀成反比关系, 这一定性结论与同腔型磁控管的定性结论并不完全一致; 在径向比较上, 结构参数对频率的影响由大到小依次为: 阳极半径, 大腔半径, 小腔半径和阴极半径; 在角向比较上, 大腔张角对频率的影响较大, 小腔张角对频率的影响较小; 另外, 模式分隔度γ 与大腔半径R_d1成正比关系, 与阴极半径R_c, 小腔半径R_d0, 小腔张角2θ₀成反比关系, 随阳极半径R_a或大腔张角2θ₁的增大先增大后减小. 关键词： 旭日型磁控管 扇形谐振腔 色散关系 场分析法     

Chodorow型耦合腔慢波结构色散特性和耦合阻抗理论分析

本文建立了Chodorow型耦合腔慢波结构的解析模型, 利用并矢格林函数结合矩量法求解了场匹配方程, 给出了色散方程和耦合阻抗的计算式, 并数值计算出一个X波段Chodorow型慢波结构的高频特性. 结果表明, 本文方法的色散特性以及耦合阻抗与仿真软件HFSS计算的结果有很好的一致性, 且计算效率更高, 同时精度远高于等效电路法, 对工程设计有好的参考价值. 关键词： Chodorow型耦合腔慢波结构 色散特性 耦合阻抗 场匹配