单光子器件及应用 - 中国人民大学理学院物理系

单光子器件及应用
孙宝权 中科院半导体研究所 超晶格国家重点实验室
半导体所
内容: 1.光认识的发展历史 2.光的统计特性 3.量子光源(单光子光源, 纠缠光源) 4.量子光源在量子信息中应用 5.总结
1. 光认识的发展历史: Light and photons
see “ introductory quantum optics” by Christopher Gerry and Peter Knight
Light and photons
* Einstein, generalized this idea, new quanta represented the light itself, describe how matter and radiation, idea of stimulated emission, the photoelectric effect. (1921获诺贝尔奖,发现光电效应, 提出光量子概念)
The normalized first-order quantum coherence function
Quantum coherence function (b) Second-order coherence functions
Hanbury-Brown and Twiss experiment. （HBT 实验）
2. 光的统计特性:Quantum coherence function (Glauber公式)
1963 年, Glauber 在 Phys.Rev.Lett, Phys. Rev. 上发表3篇文章,将量 子理论引入光学讨论光的相干性,为现代量子光学的发展奠定了基础.
Quantum coherence function (a) First-order quantum coherence function (Young’s interference experiment)
Light and photons
* 1925 to 1926, Heisenberg, Schrödinger,and Dirac laid the foundations of quantum mechanics. 海森堡 1932 创立量子力学矩阵力学方程, 提出”测不准理论”. 薛定谔 1933 提出量子力学波动力学方程. 狄拉克 1933 建立”狄拉克方程”,统一矩阵力学和波动力学.
Quantum coherence function Then the probability of obtaining a coincidence count with time delay τ is
This is the classical second-order coherence function. For quantum case;
* Seventeenth century: Concepts of waves and corpuscles were established. 1801年，杨氏(T. Young，1773-1829),做了著名的“杨氏双缝干涉实验”.
* Nineteenth century: Maxwell laid the foundations of modern field theory, light as electromagnetic waves. * Questions at the beginning of twentieth: Nature of black-body radiation Photoelectric effect. * Planck, thermal radiation was emitted and absorbed in discrete quanta in order to explain the spectra of thermal bodies. (1918 获诺贝尔奖, 提出量子假说)
经典: 0 或 1 量子: (|0>+|1>)
⏐1 > ⏐0 >
Quantum bit αI0>±i βI1>
Quantum cryptography: Feynman, Bennett, et al. Quantum computer: 1994, a quantum algorithm was discovered by Peter Shor.
Light and photons
* 1950s, Hanbury Brown, and Twiss, worked on intensity correlations as a tool in stellar interferometry. This led to the development of the theory of photon statistics, and to the beginnings of quantum optics as a separate subject.
关联函数的实验测量
精细光谱测量
飞秒激光器 HBT测量
单光子干涉测量
共聚焦显微系统
3.量子光源(单光子光源)
半导体InAs量子点单光子发射器件 (这部分工作在半导体所,超晶格国家重点实验室)
量子光源
理想的单光子源
单个二能级体系，周期地光泵或电注入电子、空穴，产生 单光子发射
经典光源
Classical light source described by Poissonian Statistics:
实验测量: 三种光场的一,二阶关联函数的实验结果, (北京师范大学,本科生,杨爽 2010年 4月在半导体所超晶格国家重点实验室,毕业实习工作)
关联函数的实验测量 不同光场的统计特性
激光测量装置 马赫-曾德尔干涉仪
赝热光产生装置
汉勃雷-布朗（Hanbury-Brown）和特威斯（Twiss）
量子点单光子光源装置
量子光源
p ( n) =
μn
n!
e
−μ
A Poisson distribution of the number of photons per pulse from strongly attenuating light pulse shows no photons in most time slots and two photons in a small number.
In the 1950s, Hanbury Brown and Twiss in Manchester developed a new kind of correlation experiment that involved the correlation of intensities rather than of field. The rate of coincident counts is proportional to the time, or ensemble, average
衰减激光
单光子
单量子点
g(2) (t) 2
相干光源
n : g( ) = 1−
70 60
400 0 1 2 3 4 5
位 移
(μm)
计 数 率 (cps)
量子光场
计 数 率 (cps)
2 4 6 8
1600 1400 1200 1000 800 600 400
50 40 30
0.22
20 -8 -6 -4 -2 0
延 迟 时 间 (ns)
0
1
2
3
4
5
位 移
(μ m )
测量光场的统计特性实验平台
关联函数的实验测量 不同光场的统计特性
1.04
1200
1.02
1000
(τ)
1.00
激光场
0 10000 20000 30000 40000 50000
计数率 (cps)
g
(2)
800
0.98
600
0.96
400
延 迟 时 间 τ (ns)
2.0
E quation A dj. R -S qua C orrrelation Intensity C orrrelation Intensity a b tao y = b+ a*exp(-t^2/tao^2) 0.97149 V alue 0.72335 1.03461 1049.012 96 S tandard E r 0.01176 0.00226
Thermal state: Coherent state: Single-mode field in a number state |n>,
Quantum coherence function Quantum coherence function (Glauber )
g(2) (t) 2 1 τc t
0
1
2
3
4
5
1.8
赝热光场
(c )
800
位移(μm)ຫໍສະໝຸດ 1.6(τ ) (2)
计 数 率 (cps)
g
1.4
C orrrelation Intensity
20.75469
700
1.2
600
1.0 0 2000 4000 6000 8000 10000 12000 14000
500
延 迟 时 间 (n s)
* Max Born, proposed intrinsic probabilistic nature of quantum mechanics. (1954获诺贝尔奖, 量子力学和波函数的统计解释)
Light and photons
* 1935, Einstein, Podolsky, and Rosen, basic nature of quantum mechanics, peculiar quantum correlations. Bohm and Bell, nature of these correlations laid the foundations-new subject of quantum information processing.
量子光源 量子光源(单光子光源)
单光子源: 稳定地发出单个光子流，这种光子 流是在一定的时间间隔内只包括一 个光子，每个光子就是一个单光子 态
单原子 单分子 金刚石NV色心 单个ZnS纳米颗粒
1
单量子点
量子光源
InAs单量子点光谱特性
量子光源 单光子发射判据(HBT)-测量光子二阶关联函数g(2)(t)
* By 1913, Bohr applied the basic idea of quantization to atomic dynamics, atomic spectral lines. (1922获诺贝尔奖, 发展量子理论,并用于原子结构,原子辐射)
* De Broglie, imagination generalized what we know about light quanta, exhibiting wave and particle properties to matter itself. (1929获诺贝尔奖, 发现电子的波动性, 提出”物质波”概念)
* 1960s, Glauber, quantum theory of coherence, the statistical properties of the light. (2005获诺贝尔奖, 光相干的量子理论)
Light and photons
* quantum cryptography, quantum computation New fundamental concepts in information processing, leading to quantum cryptography and quantum computation, have been developed in recent years. Instead of using classical bits that can represent either the values 0 or 1, the basic unit of a quantum computer is a quantum mechanical two-level system (qubit) that can exist in coherent superpositions of the logical values 0 and 1.