SHF: Small: Global Manipulation in Solid-State Quantum Information Processing - Protocols and Implementation

近年来，量子物理被应用于计算复杂性问题的研究，已成为计算机科学的一个新前沿。按照量子力学规律运行的计算机硬件可以实现新的量子协议，并为某些计算难题带来巨大的速度提升。实现这种硬件的关键问题是实现对量子逻辑元件的高度精确和快速控制，以使它们能够抵御环境噪声的有害影响。对于固态量子处理器，包括超导系统和半导体系统，这种控制通常是通过可调的局部参数来实现的，其中需要仔细设计电路和与外部源的连接。在这个项目中，将利用量子全局模式来实现量子协议的有效实现。在这里，量子全局模式是毫米波长的纳米级量子谐振器中的微波光子模式，可以同时与多个量子逻辑元件耦合，并且已经证明了微秒级的量子相干时间。同时，全局模式也被认为是测量固态量子处理器中量子纠缠和量子相干效应的探针。这个项目将研究两个问题。首先，将研究可以模拟涉及固态元素阵列的量子多体系统的固态量子模拟器，其中全局量子模式将作为模拟器中量子相变的控制和检测器。其次，将研究超导系统中伪二能级涨落子的通用量子计算机，其中全局模式可以提供个体控制，有效耦合和涨落子状态的读出。硬件方面和软件方面都将进行研究。

Quantum physics has been applied to study problems in computing complexity in recent years, which has become a new frontier in computer science. Computer hardware that is operated according to the laws of quantum mechanics can realize novel quantum protocols and bring enormous speed-up for certain computationally hard problems. The key issue in implementing such hardware is in achieving highly accurate and fast control on the quantum logic elements so that they can beat the hazardous effects from the environmental noise. For solid-state quantum processors, including superconducting systems and semiconductor systems, such control is usually achieved via adjustable local parameters, where careful designing of the circuit and the connections to external sources are required. In this project, a quantum global mode will be exploited to achieve efficient implementation of the quantum protocols. Here, the quantum global mode is the microwave photon mode in a nanoscale quantum resonator that has millimeter wavelength, can couple with multiple quantum logic elements simultaneously, and has demonstrated microsecond quantum coherence times. Meanwhile, the global mode will also be considered as a probe to measure quantum entanglement and quantum coherence effects in the solid-state quantum processors. Two questions will be studied in this project. First, solid-state quantum simulators that can emulate quantum many-body systems involving arrays of solid-state elements will be studied, where the global quantum mode will act as a control as well as a detector of the quantum phase transitions in the simulators. Second, a universal quantum computer of spurious two-level fluctuators in the superconducting system will be studied where the global mode can provide individual control, effective coupling, and readout of the fluctuator states. Both the hardware aspect and the software aspect will be investigated.