基于固态可调控超导量子电路的若干量子光学问题的研究

发布时间：2018-07-30 06:50

【摘要】：量子光学是研究光与物质相互作用的学科,它是量子场理论和物理光学的完美结合,其理论框架由仅涉及介质量子化的半经典理论和介质与光场均量子化的全量子理论组成。量子光学从诞生之日起就一直吸引着许多杰出的物理学家的注意,其研究系统也从最初的自然原子系统发展到现在各式各样的新型量子光学系统,如量子点系统、NV色心系统、光机械系统、超导量子电路系统。其中,基于约瑟夫森节的超导量子系统已经被用来展示了许多有趣的量子光学现象,从而导致了电路量子电动力学这一概念的提出。作为超导电路的核心部件,超导量子比特可以被外部的参数调谐和控制,其行为类似人造的多能级原子。因此,与传统的腔量子电动力学相比,电路量子电动力学系统具有极大的调谐性和可控性,从而可以通过调控来实现灵活的量子光学现象。本文的研究工作就是借助超导电路这一系统来开展的,并取得了一些创新性的成果,主要有：1.利用由一个驱动的超导电荷比特与一个传输线谐振子强耦合或者超强耦合相互作用所组成的电路量子电动力学系统,我们展示了量子Zeno效应的理论研究。借助于缀饰态方法,我们预测了在两种相反的投影测量下的缀饰比特的动力学行为。对于非常频繁的重复测量,我们研究显示缀饰比特初始态的生存几率具有指数形式,并且其Zeno时间长于裸比特两个数量级。对于缓慢的重复测量,我们发现驱动场的失谐量对比特的测量动力学有重要的影响,而且在恰当的系统参数下,Zeno效应在非共振耦合情形下出现了。我们强调,对于一个通常的两能级系统,这种Zeno效应不能发生。2.通过驱动一个由电荷比特与传输线谐振子强耦合所构成的有效的三能级超导缀饰系统,我们研究了电磁感应透明和Autler-Townes分裂。在缀饰态框架和稳态近似下,我们深入的研究了该系统对一个弱探测信号的线性响应。借助于谱线分解方法和其余的限制条件,我们获得了缀饰态系统的电磁感应透明和Autler-Townes分裂实现的详细条件,并呈现了一个相应的“相图”。与一般的裸系统相比,这些被获得的条件对比特-谐振子系统的参数有额外的依赖。作为结果,通过调谐比特的约瑟大森耦合能,我们呈现了从电磁感应透明到Autler-Townes分裂的跃迁。我们的研究再次显示了固态超导量子电路可调谐性的优点。3.我们研究了四能级V-型超导系统的电磁感应透明和Autler-Townes分裂。该系统由超导量子干涉仪耦合的两个超导电荷比特构成,我们给出了其本征值和本征态的一般解。我们研究发现,对于探测场的吸收谱线,这个四能级系统可以展示多个dip,至多3个dip,这打破了传统的对应关系：N+1能级系统最多显示N-1个dip。通过把这个四能级系统分解成两个三能级子系统,我们对于这一发现给出了一个合理的解释。我们也显示,通过调谐系统的参数,吸收峰和dip的角色是可以交换的。4.利用一个可循环跃迁的△-型三能级超导量子比特,我们研究了非线性多波混频现象。由于选择定则在这个系统中的缺乏,我们首次在理论上论证了三波、四波和五波混频能共存。对于仅仅一个超导比特,四波混频的效率就可以高达0.1%,这可以与先前的许多原子系统的波混效率相比较甚至更大。我们也显示三波和五波混频信号的谱线发生了Autler-Townes分裂,并且量子干涉对总的信号——三波和五波混频信号的相干叠加——有重要的影响。5.利用一个循环驱动的三能级超导约瑟夫森系统,我们研究了一种新型的相位和频率敏感的微波放大和减小。不同于先前的纯粹的相位敏感放大的线性理论,一种新的物理机制——非线性波混和波干涉的共同作用——被提出,不仅导致了信号的放大而且也能导致减小,这被称之为干涉非线性光学。我们研究显示,通过调谐相对相位,输出信号经历了从大的增益到深深的抑制的跳跃式转变,从而该系统可充当一个相位控制的振幅调制器。此外,通过改变驱动场的频率,我们显示了输出信号从放大到减小的连续变化,从而系统可充当一个频率控制的振幅调制器。我们的研究为微波信号在量子信息科学中的宽广的应用打开了一个新的视角。
[Abstract]:Quantum optics is a study of the interaction between light and matter. It is a perfect combination of quantum field theory and physical optics. Its theoretical framework consists of a semiclassical theory involving only medium quantized semiclassical theory and a quantum theory of both medium and light field. Quantum optics has attracted many outstanding physicists from the date of its birth. The research system has also developed from the original natural atomic system to various new quantum optical systems, such as the quantum dot system, the NV color center system, the optical mechanical system, the superconducting quantum circuit system. Among them, the superconducting quantum system based on the Joseph Sen's section has been used to show many interesting quantum optical phenomena. As the core component of the superconducting circuit, the superconducting qubits can be tuned and controlled by the external parameters, and their behavior is similar to the artificial multilevel atom. Therefore, compared with the traditional cavity quantum electrodynamics, the circuit quantum electrodynamics system has a great tunability and can be used. It can be controlled to achieve flexible quantum optical phenomena through regulation and control. The research work of this paper is carried out by the system of superconducting circuits, and some innovative results have been obtained, mainly: 1. the strong coupling or super coupling interaction of a driven superconducting charge bit with a transmission line harmonic oscillator. In the circuit quantum electrodynamics system, we show the theoretical study of the quantum Zeno effect. By using the ornament state method, we predict the dynamic behavior of the decorated bits under two opposite projection measurements. For very frequent repeated measurements, we have shown that the survival probability of the initial state of the decorated bits has an exponent. The form, and its Zeno time is two orders of magnitude longer than the bare bit. For slow repeated measurements, we find that the detuning of the drive field has an important effect on the measurement dynamics of the bit, and under the appropriate system parameters, the Zeno effect appears in the non resonant coupling case. We emphasize that for a normal two level system, this The Zeno effect can not occur by.2. by driving an effective three level superconducting system composed of the strong coupling of the charge bit and the harmonic oscillator of the transmission line. We studied the electromagnetic induction transparency and the Autler-Townes splitting. In the ornament state framework and the steady state approximation, we studied the system's linearity to a weak detection signal. In response. By means of spectral line decomposition and the remaining constraints, we obtain the detailed conditions for the implementation of the electromagnetic induction transparency and Autler-Townes splitting of the ornament state system, and present a corresponding "phase diagram". Compared with the general bare system, these conditions have an additional dependence on the parameters of the bit harmonic subsystem. As a result, by tuning the Jose A Sen coupling energy of the bit, we present the transition from the electromagnetic induction to the Autler-Townes splitting. Our study again shows the advantage of the tunability of the solid-state superconducting quantum circuit.3.. We have studied the electromagnetically induced transparency and the Autler-Townes splitting of the four level V- superconducting system. The two superconducting charge bits of the superconducting quantum interferometer are composed of two superconducting charge bits. We give the eigenvalues and the general solutions of the eigenstates. We find that, for the absorption spectrum of the detection field, this four level system can display multiple dip, up to up to 3 dip, which breaks the traditional corresponding relationship: the N+1 level system shows up to N-1 dip. through the most. The four level system is decomposed into two three energy level subsystems. We give a reasonable explanation for this discovery. We also show that by the parameters of the tuning system, the absorption peak and the role of dip are a convertible.4. using a cyclic transition delta type three level superconducting qubit. We have studied the nonlinear multi wave. Mixing phenomenon. Due to the lack of the selection rule in this system, we have theoretically demonstrated that the three wave, four wave and five wave mixing can coexist for the first time. For only one superconducting bit, the efficiency of four wave mixing can be as high as 0.1%, which can be compared to the wave mixing efficiency of many previous atomic systems. We also show the three wave. The spectral lines of the five wave mixing signal have Autler-Townes splitting, and the coherent superposition of the quantum interference to the total signals - the three and five wave mixing signals - has an important effect on the use of a circular driven three level superconducting Joseph Sen system. We have studied a new type of phase and frequency sensitive microwave amplification. The reduction. Different from the previous linear theory of pure phase sensitive amplification, a new physical mechanism - the common effect of nonlinear wave mixing and wave interference - is proposed not only to amplify the signal but also to decrease, which is called interference nonlinear optics. We have shown that the output is tuned by tuning the relative phase. The signal has undergone a jump transition from a large gain to a deep suppression so that the system can act as a phase controlled amplitude modulator. In addition, by changing the frequency of the drive field, we show the continuous change of the output signal from the amplification to the decrease, thus the system can be filled as a frequency controlled amplitude modulator. The research opens up a new perspective for the wide application of microwave signals in quantum information science.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O431.2

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