CAREER: Josephson Quantum Optics with Coherent Microwave Light

量子计算机承诺运行比已知最快的经典计算机快数倍的算法，并模拟一般的量子系统。这在生物和化学领域尤其令人兴奋，在这些领域，了解复杂分子可能会开辟新的途径，例如在药物发现和太阳能电池以及基础研究方面。量子计算有许多物理平台，其中两种主要的方法是光频光与原子系统的相互作用(称为量子光学)和微波频率光与超导、约瑟夫森结电路的相互作用。虽然每种方法都有独特的优点，但都不能实现大规模的量子机。此外，由于操作频率和材料要求的巨大差异，这两个平台不能很容易地组合在一个量子电路中。这个职业项目将利用超导电路的极大灵活性，将量子光学的技术和概念应用到一系列新的混合设备中，这一系列设备可能被称为“约瑟夫森量子光学”。该项目将生产能够为新一代量子机器提供动力的设备，以及支持尖端量子微波设计技术的研究生培训。超导量子电路结合了低损耗超导微波元件和约瑟夫森结的非线性电感，是实现量子机的主要平台，近年来在展示量子计算的基本要求方面取得了很大进展。然而，大规模、无错误的量子计算机需要对其信息比特进行逻辑编码，以跨多个物理比特进行编码，以便任何单个错误都不会破坏它们，从而导致构建量子计算机所需的电路元件数量大幅增加。量子元素远距离链接的体系结构(原子物理和量子光学领域的专长)，而不仅仅是它们最近的邻居，可以极大地减少纠正错误所需的硬件开销。该项目将在很大程度上借鉴光学频率量子光学以及浴缸工程的概念，开发以容忍损耗和电路缺陷的方式产生和检测量子光的新状态的设备。项目研究目标包括开发直流驱动的高度相干的基于量子比特的微脉泽和一种吸收的、高效的福克态探测器。这里提出的设备和概念将提高我们构建大型、纠错超导电路的能力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum computers promise to run algorithms which are exponentially faster than their fastest known classical counterparts, as well as simulate general quantum systems. This is especially exciting in the fields of biology and chemistry where understanding complex molecules may open new avenues, for instance in drug discovery and solar cells, as well as basic research. A number of physical platforms for quantum computing exist, with two of the leading methods being optical-frequency light interacting with atomic systems (known as quantum optics) and microwave-frequency light interacting with superconducting, Josephson-junction based circuits. While each method has unique virtues, neither is yet capable of realizing large-scale quantum machines. Further, the two platforms cannot be readily combined in a single quantum circuit due to their vastly different frequencies of operation and materials requirements. This CAREER project will leverage the extreme flexibility of superconducting circuits to adapt techniques and concepts from quantum optics into a new series of hybrid devices which may be referred to as "Josephson Quantum Optics". This project will produce devices which can power a new generation of quantum machines, as well as support graduate student training in cutting-edge quantum microwave design techniques. Superconducting quantum circuits, which combine low-loss superconducting microwave elements with the nonlinear inductance of Josephson junctions, are a leading platform for realizing quantum machines, having made great progress in recent years in demonstrating the basic requirements of quantum computing. Large scale, error-free quantum computers, however, require encoding their bits of information logically across a number of physical bits so that no single error can destroy them, resulting in a huge expansion in the number of circuit elements required to build a quantum computer. An architecture in which quantum elements are linked over long distances (a specialty of the field of atomic physics and quantum optics), rather than only to their nearest neighbors, can greatly reduce the hardware overhead required to correct errors. This project will draw heavily from concepts in optical-frequency quantum optics as well as bath engineering to develop devices which generate and detect novel states of quantum light in ways that are tolerant of loss and circuit imperfections. Project research aims include the development of dc-driven highly-coherent qubit-based micromasers and an absorptive, highly-efficient Fock-state detector. The devices and concepts proposed here will advance our ability to build large, error corrected superconducting circuits.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.