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所在平台: Coursera |
课程主页: https://www.coursera.org/learn/quantum-optics-two-photons
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课程名称：量子光学2 - 两个光子及更多 课程概述： “量子光学1，单光子”课程让学习者了解了光量子化的基本原理以及量子光学的标准形式；所有示例均基于单光子现象，包括在量子技术中的应用。秉承相同精神，“量子光学2，两个光子及更多”课程使学习者能够运用量子光学的形式化方法描述纠缠光子的特性，这是第二次量子革命的根本特征及其在量子技术中的应用。学习者将探索量子光学形式化如何描述经典光，无论是像激光光那样的相干光，还是像热辐射那样的非相干光。通过多光子的描述，课程将导出所谓的标准量子极限（SQL），并理解新型量子光态（如压缩光态）如何突破这一限制，这是量子计量学的一项成就。课程还将展示基于纠缠光子的几种量子技术，首先是在量子通信中，特别是量子传输和量子密码学。量子计算和量子模拟也会被介绍，包括有关最近提出的噪声中等规模量子（NISQ）计算的见解，这引发了对证明量子优势的希望，即能够比经典计算机以指数速度进行计算的可能性。 课程大纲： 第1部分：辐射的准经典状态：单模情况 在本节中，您将学习辐射的准经典状态形式化方法，了解其与光子和光的经典场特性的联系。 第2部分：多模准经典状态 在这一部分中，您将学习如何利用多模准经典光状态描述实际经典光，包括光束分裂器上的波包行为等。 第3部分：压缩光：突破标准量子极限 您将了解压缩光态，这种非经典光态能够进行比标准量子极限更精确的测量，及其在探测引力波中的应用。 第4部分：纠缠：革命性概念 您将了解纠缠的特点及其在信息处理中的潜在应用，尤其是光子偏振纠缠的实例及贝尔不等式的实验。 第5部分：基于纠缠的量子技术 本节涵盖基于纠缠的量子密码学和量子传输的原理，以及建设长期量子网络的挑战和量子模拟器的基本概念。这为解决复杂的物理现象和实际优化问题提供了前景。
Part: 1
Title:QUASI-CLASSICAL STATES OF RADIATION: SINGLE MODE CASE
Description:In this lesson you will discover the formalism of quasi-classical states of radiation. Introduced by Roy Glauber in the early 1960's, it has allowed one to fill the gap between the notion of photon, at the heart of quantum optics, and the fundamental property of light considered as a classical field, its coherence. You will understand why the classical model of light is so successful. You will also understand what is the shot noise, and the associated Standard Quantum Limit (SQL). It will allow you to better appreciate, in future lessons, the possibility to pass that Standard Quantum Limit, which was considered for a long time an ultimate limit.
Part: 2
Title:MULTIMODE QUASI-CLASSICAL STATES OF RADIATION
Description:In this lesson you will learn how to use multimode quasi-classical states of light to describe real classical light, with several components. You will find the demonstration of the behaviour of a quasi-classical wave packet on a beam-splitter, a property used in quantum optics 1 to show the dramatic difference between a classical and a single photon wave packet. You will also learn how to describe in quantum optics the observation of a beatnote between two lasers. This is an interesting subject in itself, which raised many discussions in the years following the invention of lasers, and which is crystal clear when discussed as in this lesson. It is also a much used technique in AMO laboratories, known a heterodyne detection, of which you will learn the interest and the limits. You will also encounter some fundamental ideas about incoherent vs coherent muitimode radiation, and about similarities and differences between a classical statistical average and a quantum average. With these notions, you will be armed to better appreciate specific quantum properties of squeezed light, presented in the next lesson.
Part: 3
Title:SQUEEZED LIGHT: BEATING THE STANDARD QUANTUM LIMIT
Description:In this lesson, you will learn about non-classcal states of light, squeezed states, which allow one to "beat the Standard Quantum Limit", ie, to realize measurements with an uncertainty smaller than what was considered the ultimate limit, which in fact applies to a perfectly controlled classical beam of light, either a laser beam or a beam from a standard source. The notion of squeezed states of light was discovered in 1980, in the hope to succeed in detecting gravitational waves with giant optical interferometers. Almost 40 years later, Squeezed States of Light are effectively used with these giant interferometers, and they promise to increase significantly the volume of the universe explored by these interferometers. This is an example of a quantum technology based on a multi-photons quantum state, without any classical equivalent.
Part: 4
Title:ENTANGLEMENT: A REVOLUTIONARY CONCEPT
Description:Entanglement is a quantum mechanical feature which was ignored or underestimated for a long time, in spite of the debate between Einstein and Bohr about it. It is only with John Bell's discovery, in the mid 1960's, that one could experimentally settle the debate, that some physicists realized the possibility to use entanglement for new ways of processing and transmitting information. In this lesson, you will learn about entanglement and Bell's inequalities tests, about the case of a pair of photons entangled in polarization, which is the system that has lead to the first convincing experiments. consequences about our understanding of the quantum world will be addressed, leaving to the next lesson the description of some quantum technologies based on entanglement.
Part: 5
Title:ENTANGLEMENT BASED QUANTUM TECHNOLOGIES
Description:The second quantum revolution is not only conceptual, with the understanding of the extraordinary character of entanglemnt, but it also promises to be technological, with applications impossible to conceive before realizing the potential of entanglement. Entanglement based quantum cryptography and the fascinating concept of quantum teleportation are the quantum technologies at the root of quantum networks, the so-called quantum internet, and in this lesson you will understand in detail their principles. In order to build a long distance quantum network, one needs good quantum memories, a very important challenge at the moment. You will also find in this lesson, with less details, the basic idea of quantum simulators, which was introduced by Feynman in 1982, but which came of age only in the recent years. It offers, in 2019, the fascinating perspective not only to elucidate physics phenomena too hard to be solved on a classical computer, such as High Critical Temperature Superconduction, but also to solve hard practical optimization problems, thanks to the concept of NISQ (Noisy Intermediate Scale Quantum) simulators, which do not need to be perfect.
"Quantum Optics 1, Single photons", allowed learners to be introduced to the basic principles of light quantization, and to the standard formalism of Quantum Optics. All the examples were taken in single photons phenomena, including applications to quantum technologies. In the same spirit, "Quantum Optics 2, Two photons and more", will allow learners to use the Quantum Optics formalism to describe entangled photon, a unique feature at the root of the second quantum revolution and its applications to quantum technologies. Learners will also discover how the Quantum Optics formalism allows one to describe classical light, either coherent such as laser light, or incoherent such as thermal radiation. Using a many photons description, it is possible to derive the so-called Standard Quantum Limit (SQL), which applies to classical light, and to understand how new kinds of quantum states of light, such as squeezed states of light, allow one to beat the SQL, one of the achievements of quantum metrology. Several examples of Quantum Technologies based on entangled photons will be presented, firstly in quantum communication, in particular Quantum Teleportation and Quantum Cryptography. Quantum Computing and Quantum Simulation will also be presented, including some insights into the recently proposed Noisy Intermediate Scale Quantum (NISQ) computing, which raises a serious hope to demonstrate, in a near future, the actively searched quantum advantage, ie, the possibility to effect calculations exponentially faster than with classical computers.
