Condensed Matter and Quantum Information Theory

非技术总结该奖项支持理论量子物理的研究和教育，重点是研究在微波频率和接近绝对零度的温度下工作的电路的量子特性。PI不是研究激光、光学频率的光子和单个真实原子，而是研究微波光子和由超导电路元件构成的人造原子。由于人造原子(称为量子比特)比单个真实原子大得多，它们与光子的相互作用可能比普通光与原子之间的相互作用大得多。这使得可以在全新的制度下测试量子力学的含义，并创建量子比特和光子的奇异量子态，这可以用作建造量子计算机和基于光子传输的安全量子通信的基础。该项目还将开发和研究使用光子存储和忠实传输量子信息的方法，即使光子在远距离传输过程中或在量子存储器中长时间存储期间丢失。由于最近取得了巨大的实验进展，现在有可能以前所未有的灵敏度探测单个光子。这个项目将利用这些进展提出方法，极大地加快寻找一类被称为轴子的暗物质粒子，这将在凝聚态物理和宇宙学领域之间建立重要的新联系。最后，PI将继续与实验同事合作研究量子光学力学，利用微弱的光辐射压力来控制机械物体的运动，并以前所未有的精度进行位置测量。最近在LIGO上发现的引力波就是这类研究的实际应用之一，该项目的跨学科性质和与实验的密切合作将产生更广泛的影响。PI正在促进凝聚态、原子物理、量子光学和电气工程界之间的交流。作为该项目的一部分，一名博士后研究员将接受尖端理论方法的培训。作为耶鲁物理奥林匹克的一部分，PI还负责为来自新英格兰各地的大约200名高中生举办年度讲座，重点解释量子力学和量子信息处理的想法。技术总结该奖项支持理论量子物理的研究和教育，重点是将量子光学和腔量子电动力学的想法应用到电路QED中。该项目涉及四个主要研究领域：1)超导量子比特与多模腔的强耦合：该项目将在极限情况下研究非线性量子光学，其中一米长的谐振器的自由光谱范围足够小，足以与量子比特与该谐振腔的真空Rabi耦合相媲美。因此，许多模式被联合耦合到量子比特，从而相互耦合。2)用于轴子搜索和远程纠缠的微波光子的有效检测：该项目将提出并开发新的方法来使用电路QED的工具来探测宇宙学的轴子暗物质粒子。将分析两种不同的方案，第一种方案使用双模压缩器在不放大真空噪声的情况下放大轴子信号，第二种方案使用最近开发的微波光子量子非摧毁探测能力来创建微波光子的“光电倍增管”。PI将开发一个最优的贝叶斯过滤器，以最大限度地减少探测器的暗计数率，从而显著提高相对于当前方法的轴子检测的信噪比。同样的想法也可以应用于独立腔中量子比特的远程纠缠，这将在量子计算机的发展中有重要的应用。3)用于量子存储和通信的可纠错光子码：本项目属于基本量子信息理论。它将利用新的实验能力，允许基本上通用地控制和测量少量微波光子和超导量子比特的Fock态的复杂叠加，并且在普通光学中没有类似的功能。PI将开发用于玻色子模式的近似连续量子纠错协议。这些将应用于使用微波谐振器作为量子存储器，使用微波光子进行量子通信，以及将存储在微波光子中的量子信息忠实地转换到可以通过光纤网络远距离传输的光学频率。4)光力学：这是与耶鲁大学的实验同事进行的基本量子光学合作。PI对参数空间中所谓的“例外点”附近的非绝热演化的全量子理论的发展特别感兴趣。该项目的跨学科性质和与实验的密切合作将产生更广泛的影响。PI正在促进凝聚态、原子物理、量子光学和电气工程界之间的交流。作为该项目的一部分，一名博士后研究员将接受尖端理论方法的培训。作为耶鲁大学物理奥林匹克的一部分，PI还负责为来自新英格兰各地的大约200名高中生举办年度讲座，重点解释量子力学和量子信息处理的想法。

NONTECHNICAL SUMMARYThis award supports research and education in theoretical quantum physics focusing on the study of the quantum properties of electrical circuits operating at microwave frequencies and at temperatures close to absolute zero. Rather than dealing with lasers, photons at optical frequencies, and individual real atoms, the PI studies microwave photons and artificial atoms constructed from superconducting circuit elements. Because the artificial atoms (called qubits) are enormously larger than individual real atoms, their interaction with photons can be significantly larger than the interaction between ordinary light and atoms. This permits testing the implications of quantum mechanics in completely new regimes, as well as creating exotic quantum states of qubits and photons, which can be used as the basis for building a quantum computer and for secure quantum communication based on the transmission of photons. This project will also develop and study methods for storing and faithfully transmitting quantum information using photons, even if photons are lost during transmission over long distances or during storage over long periods of time in a quantum memory. Because of recent enormous experimental progress, it is now possible to detect individual photons with unprecedented sensitivity. This project will take advantage of these advances to propose methods that will dramatically speed up the search for a certain class of dark matter particles known as axions, which will forge important new connections between the fields of condensed matter physics and cosmology.Finally, the PI will continue his collaboration with experimental colleagues to study quantum optomechanics, in which the feeble radiation pressure of light is harnessed to control the motion of mechanical objects, and make position measurements with unprecedented accuracy. The recent discovery of gravitational waves at LIGO is an example of one of the practical applications for this type of research.The project will achieve broader impacts by its interdisciplinary nature and the close collaboration with experiment. The PI is fostering communication among the condensed matter, atomic physics, quantum optics and electrical engineering communities. As part of the project a postdoctoral fellow will be trained in cutting-edge theoretical methods. The PI is also responsible for an annual lecture for approximately 200 high-school students from across New England as part of the Yale Physics Olympics, focused on explaining ideas from quantum mechanics and quantum information processing.TECHNICAL SUMMARYThis award supports research and education in theoretical quantum physics focusing on the application of ideas from quantum optics and cavity quantum electrodynamics to circuit QED. The project involves four main areas of research: 1) Strong-coupling of a superconducting qubit to a multi-mode cavity: This project will study nonlinear quantum optics in the limit where the free spectral range of a one-meter-long resonator is small enough to be comparable to the vacuum Rabi coupling of a qubit to that resonator. Thus, many modes are jointly coupled to the qubit and hence to each other.2) Efficient Detection of Microwave Photons for Axion Searches and Remote Entanglement: This project will propose and develop novel methods to use tools from circuit QED to detect cosmological axion dark-matter particles. Two different schemes will be analyzed, the first using two-mode squeezers to amplify the axion signal without amplifying the vacuum noise, and the second using recently developed capabilities for quantum non-demolition detection of microwave photons to create a "photomultiplier" for microwave photons. The PI will develop an optimal Bayesian filter to minimize the dark count rate of the detector and hence dramatically increase the signal-to-noise ratio for the detection of axions relative to current methods. The same ideas can be applied to the remote entanglement of qubits in independent cavities, which will have important application in the development of quantum computers.3) Error Correctable Photonic Codes for Quantum Memories and Communication: This project sits within fundamental quantum information theory. It will take advantage of new experimental capabilities, which allow essentially universal control and measurement of complex superpositions of Fock states of small numbers of microwave photons and superconducting qubits, and have no analog in ordinary optics. The PI will develop approximate continuous quantum error correction protocols for bosonic modes. These will have applications to using microwave resonators as quantum memories, to quantum communication using microwave photons, and to faithful conversion of quantum information stored in microwave photons up to optical frequencies where it can be transmitted large distances over fiber networks.4) Optomechanics: This is a fundamental quantum optics collaboration with experimental colleagues at Yale. The PI is particularly interested in the development of a fully quantum theory of non-adiabatic evolution near so-called "exceptional points" in the parameter space. The project will achieve broader impacts by its interdisciplinary nature and the close collaboration with experiment. The PI is fostering communication among the condensed matter, atomic physics, quantum optics and electrical engineering communities. As part of the project a postdoctoral fellow will be trained in cutting-edge theoretical methods. The PI is also responsible for an annual lecture for approximately 200 high-school students from across New England as part of the Yale Physics Olympics, focused on explaining ideas from quantum mechanics and quantum information processing.