Let Each Quantum Bit Choose Its Basis Gates
Let Each Quantum Bit Choose Its Basis Gates
复制标题
DOI：
10.1109/micro56248.2022.00075
复制
发表时间：
2022-08
期刊：
影响因子：
--
通讯作者：
Sophia Fuhui Lin;S. Sussman;Casey Duckering;Pranav S. Mundada;Jonathan M. Baker;Rohan S. Kumar;A. Houck;F. Chong
中科院分区：
文献类型：
--
作者：
Sophia Fuhui Lin;S. Sussman;Casey Duckering;Pranav S. Mundada;Jonathan M. Baker;Rohan S. Kumar;A. Houck;F. Chong
近期量子计算机主要受到两个量子比特（或量子位）之间量子操作（或门）错误的限制。物理机器通常提供一组基门，其中包括可以在给定技术中实现的原始2量子位（2Q）和1量子位（1Q）门。2Q纠缠门，加上一些1Q门，可以实现通用量子计算。在超导技术中，目前的技术水平是在每一对量子位之间实现相同的2Q门（通常是xx或xy型门）。在大型量子计算机中对2Q门的严格硬件一致性要求使得在实验室中扩展时间和资源密集型工作。我们提出了一个激进的想法——允许每对量子比特之间的2Q基门(s)不同，选择可以在给定的量子比特对之间校准的最佳纠缠门。这项工作旨在让量子科学家能够在不完全均匀的量子比特系统中运行有意义的算法。科学家们还将能够在量子计算中使用更广泛的新型2Q门。我们开发了一个理论框架，用于识别偏离“标准”轨迹（如XX）的“非标准”Cartan轨迹上的良好2Q基门。然后介绍了非标准2Q门校准和编译的实用方法，并讨论了改进编译的可能方法。为了在案例研究中演示我们的方法，我们使用具有远失谐的transmon量子比特的纠缠门架构模拟了标准xy型轨迹和更快的非标准轨迹。我们在这些非标准轨迹上识别出有效的2Q基门，并使用它们来编译一些标准基准电路，如QFT和QAOA。我们的结果表明，在速度和相干限制门保真度方面，比基线2Q门提高了8倍。
Near-term quantum computers are primarily limited by errors in quantum operations (or gates) between two quantum bits (or qubits). A physical machine typically provides a set of basis gates that include primitive 2-qubit (2Q) and 1-qubit (1Q) gates that can be implemented in a given technology. 2Q entangling gates, coupled with some 1Q gates, allow for universal quantum computation. In superconducting technologies, the current state of the art is to implement the same 2Q gate between every pair of qubits (typically an XX-or XY-type gate). This strict hardware uniformity requirement for 2Q gates in a large quantum computer has made scaling up a time and resource-intensive endeavor in the lab. We propose a radical idea – allow the 2Q basis gate(s) to differ between every pair of qubits, selecting the best entangling gates that can be calibrated between given pairs of qubits. This work aims to give quantum scientists the ability to run meaningful algorithms with qubit systems that are not perfectly uniform. Scientists will also be able to use a much broader variety of novel 2Q gates for quantum computing. We develop a theoretical framework for identifying good 2Q basis gates on “nonstandard” Cartan trajectories that deviate from “standard” trajectories like XX. We then introduce practical methods for calibration and compilation with nonstandard 2Q gates, and discuss possible ways to improve the compilation. To demonstrate our methods in a case study, we simulated both standard XY-type trajectories and faster, nonstandard trajectories using an entangling gate architecture with far-detuned transmon qubits. We identify efficient 2Q basis gates on these nonstandard trajectories and use them to compile a number of standard benchmark circuits such as QFT and QAOA. Our results demonstrate an 8x improvement over the baseline 2Q gates with respect to speed and coherence-limited gate fidelity.