Quantum Microwaves from Superconducting Quantum Circuits

点击翻译按钮获取中文摘要

Superconducting quantum circuits are a well-established platform for both fundamental and applied quantum research, as evidenced by major investments from Google, Intel, D-Wave and IBM, as well as by governments across North America, Europe and Asia. Supported by this Discovery grant, we will make important contributions to the world-wide effort to exploit this exciting technology. Analog quantum simulation is a paradigm where a quantum circuit is constructed to directly mimic or "simulate" a system of interest. The principle is the same as using a simple semiconductor circuit to simulate the trajectory of a rocket, as was common through the 1960s before digital computing power became inexpensive. Similarly, analog quantum simulation is a promising path to unlock the potential advantages of quantum computing before large-scale digital quantum computers become available. As a first testbed, we will simulate strongly-interacting quantum field theories. These theories describe fundamental models such as quantum chromodynamics, but also a wide array of technologically important quantum materials such as high-temperature superconductors. Optical Quantum Computing with Parametric Cavities - Optical quantum computing (OQC) is a major paradigm of quantum information. In standard OQC, quantum information is processed by laser light traveling on a large table top. We would instead use microwaves traveling on chip in an integrated circuit. The parametric cavities developed by my group are a promising platform for on-chip OQC using microwave photons. The functionality we have already demonstrated implements all the tools of linear quantum optics. However, it has been shown the even a complete set of linear operations cannot give a quantum speedup. So-called non-Gaussian states are needed as inputs to achieve a quantum advantage. Of particular interest is a type of "magic state," called the cubic-phase state, which has remained elusive to experimenters. Recent advances by my group have allowed us to demonstrate important building blocks of this magic state. We will continue our work to produce a useful magic state and develop on-chip OQC. Quantum illumination (QI) has recently gained attention as a possible avenue to improve the sensitivity of radar. QI applies a unique quantum effect, called entanglement. Unlike many potential quantum applications, QI seems to be very robust to noise and losses during transmission, suggesting that it may have practical applications. Recent experiments have demonstrated the basic principle of QI at optical frequencies. This is an important proof of principle, but conventional radar systems typically use microwave frequencies. Our parametric cavities are also an excellent source of the entangled microwave photons need for QI. We will build on our existing results to demonstrate microwave QI in ambient conditions. Demonstrating a quantum advantage for ambient microwaves would be an important breakthrough.