High-Fidelity Quantum Logic in Ca+
High-Fidelity Quantum Logic in Ca+
复制标题
加州高保真量子逻辑
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
C. Ballance
中科院分区：
文献类型：
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作者：
C. Ballance
高保真量子逻辑在Ca+ Christopher J. balance一篇提交给牛津大学赫特福德学院2014年Michaelmas学期哲学博士学位的论文被困原子离子是建造量子计算机最有前途的系统之一——建造量子计算机所需的所有基本操作都在这样的系统中得到了证明。现在的挑战是理解并将操作误差降低到“容错阈值”以下（量子纠错工作的水平），并将当前的少量量子比特实验扩展到许多量子比特。本文描述的实验工作主要集中在这些挑战的第一个。我们展示了高保真的单量子比特和双量子比特（纠缠）门，其误差等于或低于容错阈值。我们还实现了两个不同种类离子之间的纠缠门，这是一个可能对某些可扩展架构有用的工具。我们研究了在43Ca+超精细捕获离子量子比特中实现的双量子位相门的速度/保真度权衡。我们开发了一个误差模型，描述了导致测量门误差的基本和技术缺陷/限制。我们描述并最小化了导致测量保真度的各种误差源，使我们能够解释由于单量子位操作和状态读出（每个在0.1%水平）引起的误差，并确定了双量子位纠缠操作中的主要误差源。我们实现的门保真度范围在97.1(2)%（对于门时间tg = 3.8μs）和99.9(1)%（对于tg = 100μs）之间，分别代表了捕获离子量子比特之间最快和最低误差的两个量子比特门，在每种情况下都接近一个数量级。我们还描述了单量子比特门，每次操作的平均误差低于10−4，比以前用激光驱动操作实现的要好一个数量级。此外，我们还介绍了混合物种纠缠门的研究工作。我们以99.8(5)%的保真度对单个40Ca+离子和单个43Ca+离子进行了纠缠，并对所产生的纠缠态进行了完整的断层扫描。我们描述了这种混合种门机制如何用于纠缠43Ca+和88Sr+，这是一种有前途的离子组合，可用于未来的实验。
High-Fidelity Quantum Logic in Ca+ Christopher J. Ballance A thesis submitted for the degree of Doctor of Philosophy Michaelmas term 2014 Hertford College, Oxford Trapped atomic ions are one of the most promising systems for building a quantum computer – all of the fundamental operations needed to build a quantum computer have been demonstrated in such systems. The challenge now is to understand and reduce the operation errors to below the ‘fault-tolerant threshold’ (the level below which quantum error correction works), and to scale up the current few-qubit experiments to many qubits. This thesis describes experimental work concentrated primarily on the first of these challenges. We demonstrate high-fidelity single-qubit and two-qubit (entangling) gates with errors at or below the fault-tolerant threshold. We also implement an entangling gate between two different species of ions, a tool which may be useful for certain scalable architectures. We study the speed/fidelity trade-off for a two-qubit phase gate implemented in 43Ca+ hyperfine trapped-ion qubits. We develop an error model which describes the fundamental and technical imperfections / limitations that contribute to the measured gate error. We characterize and minimise various error sources contributing to the measured fidelity, allowing us to account for errors due to the single-qubit operations and state readout (each at the 0.1% level), and to identify the leading sources of error in the two-qubit entangling operation. We achieve gate fidelities ranging between 97.1(2)% (for a gate time tg = 3.8μs) and 99.9(1)% (for tg = 100μs), representing respectively the fastest and lowest-error two-qubit gates reported between trapped-ion qubits by nearly an order of magnitude in each case. We also characterise single-qubit gates with average errors below 10−4 per operation, over an order of magnitude better than previously achieved with laser-driven operations. Additionally, we present work on a mixed-species entangling gate. We entangle of a single 40Ca+ ion and a single 43Ca+ ion with a fidelity of 99.8(5)%, and perform full tomography of the resulting entangled state. We describe how this mixed-species gate mechanism could be used to entangle 43Ca+ and 88Sr+, a promising combination of ions for future experiments.
影响因子：
16.6
作者：
C. Piltz;T. Sriarunothai;A. F.Var'on;Ch. Wunderlich
通讯作者：
C. Piltz;T. Sriarunothai;A. F.Var'on;Ch. Wunderlich
影响因子：
2.9
作者：
Bermudez, A.;Schmidt, P. O.;Retzker, A.
通讯作者：
Retzker, A.
影响因子：
8.6
作者：
Harty, T. P.;Allcock, D. T. C.;Lucas, D. M.
通讯作者：
Lucas, D. M.