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Dynamically Corrected Nonadiabatic Geometric Quantum Logic Gates

动态校正非绝热几何量子逻辑门

基本信息

批准号：
1915064
负责人：
Jason Kestner
金额：
$ 30万
依托单位：
University of Maryland Baltimore County
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1915064&HistoricalAwards=false
关键词：
Dynamically Corrected Nonadiabatic Geometric Quantum

项目摘要

The prospect of quantum computing has the potential to transform the landscape of our information-based economy. However, the idea of quantum computing was initially deemed to be a nonstarter because of its reliance on creating blends of exponentially large numbers of possible states of the quantum computer, blends whose delicate balance could easily be ruined by even very small errors. Quantum computing was rescued by the notion of quantum error correction, which uses a large number of physical bits to encode each logical bit and inserts into each computation a series of periodic measurements, error diagnosis, and subsequent remediation to achieve fault-tolerance. In order for this to work, though, the fidelity of each operation on a physical qubit has to be above a certain threshold, called the fault-tolerance threshold of the particular encoding scheme. The fault-tolerance threshold is around 99% for surface codes, and around 99.99% for other codes. While a few experiments have shown one-qubit and two-qubit fidelities above the surface code threshold, in general raising the fidelity remains a major challenge for quantum computing to become a reality. This research addresses that challenge by constructing control protocols that are robust to noise.The approach taken is to combine the strengths of dynamical decoupling and nonadiabatic geometric gating. Dynamical decoupling is effective in suppressing low-frequency noise, but tends to exacerbate high-frequency noise. Nonadiabatic geometric gate operations are effective in suppressing high-frequency noise, but are sensitive to parametric low-frequency noise. By fusing the two concepts, this research seeks efficient suppression of errors over a broad noise bandwidth without requiring auxiliary energy levels. The major research aims are to find the filter functions of single-qubit nonadiabatic geometric gates that characterize their robustness to noise at all frequencies, to combine with single-qubit dynamical decoupling techniques to improve the filter function at low frequencies, to incorporate physical constraints for experimental implementation, and to use the insight from the single-qubit considerations to extend the new framework to two-qubit entangling operations, attaining a universal set of robust nonadiabatic geometric gates amenable to solid state experiments. Success will be assessed via the average error rates calculated from numerical simulations.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.

量子计算的前景有可能改变我们以信息为基础的经济格局。然而，量子计算的想法最初被认为是不可能的，因为它依赖于创造量子计算机的指数级大量可能状态的混合，这些混合的微妙平衡很容易被非常微小的错误破坏。量子纠错的概念拯救了量子计算，量子纠错使用大量的物理比特对每个逻辑比特进行编码，并在每次计算中插入一系列定期测量、错误诊断和后续补救以实现容错。然而，为了使其发挥作用，对物理量子比特的每一次操作的保真度都必须高于某个阈值，该阈值称为特定编码方案的容错阈值。表面代码的容错阈值约为99%，其他代码的容错阈值约为99.99%。虽然一些实验表明，一量子比特和两量子比特的保真度高于表面代码的阈值，但总的来说，提高保真度仍然是量子计算成为现实的主要挑战。这项研究通过构造对噪声具有鲁棒性的控制协议来解决这一挑战，所采取的方法是结合动态解耦和非绝热几何门控的优点。动态解耦对抑制低频噪声是有效的，但往往会加剧高频噪声。非绝热几何门运算能有效地抑制高频噪声，但对参变低频噪声很敏感。通过融合这两个概念，这项研究寻求在宽噪声带宽上有效地抑制误差，而不需要辅助能级。主要的研究目的是找到单量子比特非绝热几何门在所有频率下对噪声的鲁棒性，结合单量子比特动态解耦技术来改进低频下的滤波函数，为实验实现考虑物理约束，并利用单量子比特考虑的洞察力将新框架扩展到两量子比特纠缠操作，获得一套适用于固态实验的健壮的非绝热几何门集。成功将通过数值模拟计算的平均错误率进行评估。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。