弱测量理论及其在光机械系统中的应用

发布时间：2018-06-06 11:49

本文选题：弱测量 + 光机械系统　；参考：《大连理工大学》2016年博士论文

【摘要】：关于量子力学基本原理的研究不仅丰富我们的科学知识,而且也增进我们对自然法则的理解。这些研究也推动许多技术应用的发展,如量子非定域性问题已经被应用于量子密码学,波粒二象性的理解使半导体技术成为可能以及薛定谔猫的研究促进量子信息处理和通信领域发展。在检查量子测量过程中,由阿哈罗洛夫(Aharonov),艾伯特(Albert)和魏德曼(Vaidman)引入系统和指针之间弱耦合的弱测量概念,并且定义了所测系统观测量的弱值。系统观测量的弱值可以超出了系统观测量的本征值范围。弱值的特征通常被认为是弱信号的放大效应。首次,用光学手段实现弱值之后,它被应用在不同领域为观察非常小的效果,如光速偏转、频率偏移、相位偏移、角度偏移、速度偏移、甚至温度偏移。尽管弱测量有很多应用,但是在光机械中它的应用很少被报道。众所周知,当只有一个光子在光机械腔中,由单光子引起的镜子位置的平移很难被探测,那是因为它远小于镜子波包的传播幅度。换句话说,一个光子的辐射压力很难被测量。因此,在当前实验条件下,能否使用弱测量方法来放大一光子的辐射压力是非常有意义的。在第一章中,阐述了论文的研究背景,接下来在第二章介绍了一些基础知识。本论文的主要工作分布在第三章到第五章。第三章和第四章,主要研究不同量子指针的弱测量如何来提高光机械系统中镜子位置的平移。在第三章,基于与弱测量相结合的光机械系统,当镜子(量子指针)初始化为基态时,我们发现镜子位置的平移可以被放大,此放大效应发生在光子的后选择态正交于光子的初态这个情况下,那是不能被通常的弱测量结论解释,并且它的最大放大值可以达到基态涨落程度。在第四章中,当镜子用压缩相干态代替基态时,我们发现镜子位置的平移可以被放大。这个放大取决于压缩态的增加涨落,那归因于量子力学的非交换性。在第五章,基于与光机械系统相结合的量子延迟选择实验,利用弱测量方法,我们研究具有后选择作用的控制Hadamard门,并发现由它控制的波粒二象性可以作为放大的产生机制。最后,在第六章中给出论文的总结与展望。
[Abstract]:The study of the fundamental principles of quantum mechanics not only enriches our scientific knowledge, but also enhances our understanding of the laws of nature. These studies also promote the development of many technical applications, such as quantum nonlocality, which has been applied to quantum cryptography. The understanding of wave-particle duality makes semiconductor technology possible and Schr 枚 dinger's research promotes the development of quantum information processing and communication. In the process of checking quantum measurement, the weak measurement concept of weak coupling between system and pointer is introduced by Aharonovi, Albert and Vaidman), and the weak value of observed system is defined. The weak value of the system observation can exceed the eigenvalue range of the system observation. The characteristic of weak value is usually considered to be the amplification effect of weak signal. For the first time, after realizing the weak value by optical means, it is applied in different fields to observe very small effects, such as light speed deflection, frequency offset, phase shift, angle shift, velocity shift, and even temperature shift. Although weak measurement has many applications, its applications in optical machinery are rarely reported. It is well known that when there is only one photon in the optical mechanical cavity, the translation of the mirror position caused by single photon is difficult to detect, because it is far less than the propagation amplitude of the mirror wave packet. In other words, the radiation pressure of a photon is difficult to measure. Therefore, under the present experimental conditions, it is very meaningful to use weak measurement method to amplify the radiation pressure of a photon. In the first chapter, the research background of the thesis is described, and then some basic knowledge is introduced in the second chapter. The main work of this thesis is from Chapter 3 to Chapter 5. In the third and fourth chapters, we mainly study how the weak measurement of different quantum pointers can improve the translation of mirror position in optomechanical systems. In Chapter 3, based on the optical mechanical system combined with weak measurement, when the mirror (quantum pointer) is initialized to the ground state, we find that the translation of the mirror position can be amplified. This amplification effect occurs in the case that the post-selective state of the photon is orthogonal to the initial state of the photon, which cannot be explained by the usual weak measurement conclusion, and its maximum amplification value can reach the ground state fluctuation. In Chapter 4, when the ground state is replaced by the squeezed coherent state, we find that the translation of the mirror position can be amplified. This amplification depends on the increasing fluctuations of the squeezed states, which are attributed to the non-commutativity of quantum mechanics. In chapter 5, based on the quantum delay selection experiment combined with the optomechanical system, we study the control Hadamard gate with the function of post-selection by using the weak measurement method, and find that the wave-particle duality controlled by the gate can be used as the mechanism of amplification. Finally, the conclusion and prospect of the thesis are given in the sixth chapter.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O413.1

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