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Entangling Qubits with High Fidelity via Nonlocal Echo Sequences

通过非局部回波序列以高保真度纠缠量子位

基本信息

批准号：
1620740
负责人：
Jason Kestner
金额：
$ 21万
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：
2016
资助国家：
美国
起止时间：
2016-09-01 至 2020-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1620740&HistoricalAwards=false
关键词：
Entangling Qubits Fidelity via Nonlocal

项目摘要

Quantum computers have the potential to provide numerous benefits for the modern information-based economy, for example faster search algorithms, enhanced security, and more efficient ways to do mathematical calculations. However, it is challenging to make reliable components, such as quantum gates, for quantum computers. A quantum computer operates quite differently from current computers, since it takes advantage of the fact that an unusual set of rules, quantum mechanics, governs the behavior of the very small objects that make up the logical bits, or "qubits" of the computer. The problem is that qubits are very delicate, and any imperfections in the control or undesired perturbations (noise) can ruin the computation. The goal of this project is to discover ways to operate a quantum computer so that it self corrects certain types of errors that may occur during the computation. This will be done through the use of a controlled sequence of light pulses to "entangle" pairs of qubits, a unique feature of quantum mechanics that allows them to share information in such a way that it cannot be accessed by measuring the qubits individually. By designing a sequence of control signals that can reliably entangle pairs of qubits, it should be possible to enable qubits to undergo a self-correcting trajectory and end up in a particular, desired quantum state even in the presence of noise, bringing the field of quantum computation a step closer to realization. This project will produce a novel two-qubit dynamically protected entangling protocol that assumes only access to high-fidelity single-qubit gates (which can be produced with existing methods) and a noisy, but well-characterized, two-qubit gate. The primary application of this project will be to the entangling of quantum dot spin qubits, since noise in these otherwise very promising systems is particularly limiting at the moment. The noise (both electrical and hyperfine) is predominantly low-frequency, typically with a 1/f power spectral density, so that such a composite pulse sequence approach is reasonable. A combination of analytical and computational methods will be used to search for optimally robust sequences, using simulated randomized benchmarking to characterize their performance. The solutions will be designed to be modular such that they can be used simultaneously with pulse shaping and other fidelity-enhancing techniques to substantially reduce errors within the logical space of any qubit platform. This is a vital step towards the application of scalable, fault-tolerant quantum computing.

量子计算机有潜力为现代信息经济提供众多好处，例如更快的搜索算法、增强的安全性以及更有效的数学计算方法。然而，为量子计算机制造可靠的组件（例如量子门）具有挑战性。量子计算机的运行方式与当前计算机完全不同，因为它利用了一组不寻常的规则，即量子力学，控制着构成计算机逻辑位或“量子位”的非常小的对象的行为。问题在于量子位非常脆弱，控制中的任何缺陷或不需要的扰动（噪声）都可能破坏计算。该项目的目标是发现操作量子计算机的方法，以便它能够自我纠正计算过程中可能发生的某些类型的错误。这将通过使用受控的光脉冲序列来“纠缠”成对的量子位来完成，这是量子力学的一个独特功能，允许它们以无法通过单独测量量子位来访问的方式共享信息。通过设计一系列能够可靠地纠缠量子位对的控制信号，即使存在噪声，量子位也能经历自我校正轨迹并最终处于特定的、期望的量子态，从而使量子计算领域更接近实现。该项目将产生一种新颖的双量子位动态保护纠缠协议，该协议假设只能访问高保真单量子位门（可以使用现有方法生成）和一个嘈杂但特征良好的双量子位门。该项目的主要应用将是量子点自旋量子位的纠缠，因为这些原本非常有前途的系统中的噪声目前特别受到限制。噪声（电噪声和超精细噪声）主要是低频噪声，通常具有 1/f 功率谱密度，因此这种复合脉冲序列方法是合理的。将结合分析和计算方法来搜索最佳鲁棒序列，并使用模拟随机基准测试来表征其性能。该解决方案将被设计为模块化，以便它们可以与脉冲整形和其他保真度增强技术同时使用，以大幅减少任何量子位平台逻辑空间内的错误。这是迈向可扩展、容错量子计算应用的重要一步。