Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms
Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms
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DOI：
10.1103/physrevlett.125.120504
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发表时间：
2020-09-15
影响因子：
8.6
通讯作者：
Martinis, J. M.
中科院分区：
文献类型：
--
作者：
Foxen, B.;Neill, C.;Martinis, J. M.
量子算法为材料科学和化学中的计算问题提供了显着的加速。然而，这些算法的任何近期实现都需要进行优化，以适应现有噪声硬件提供的有限资源。在这里，利用gmon量子位的可调耦合，我们展示了一个连续的两量子位门集，与标准分解相比，它可以提供三倍的电路深度减少。我们实现了两个门的家庭：一个虚构的交换（iSWAP样）门，以达到任意的交换角，θ，和一个控制相位门，产生一个任意的条件相位，φ。使用这些门中的每一个，我们可以在激发保持子空间内执行任意的两量子比特门，从而允许完整实现所谓的费米模拟（fSim）门集。我们对iSWAP和受控相位门系列以及均匀分布在整个tSim（theta，phi）参数空间中的525个其他'Sim门的保真度进行了基准测试，实现了每个fSim门3.8 x 10（-3）的纯度限制平均两量子位泡利误差。
Quantum algorithms offer a dramatic speedup for computational problems in material science and chemistry. However, any near-term realizations of these algorithms will need to be optimized to fit within the finite resources offered by existing noisy hardware. Here, taking advantage of the adjustable coupling of gmon qubits, we demonstrate a continuous two-qubit gate set that can provide a threefold reduction in circuit depth as compared to a standard decomposition. We implement two gate families: an imaginary swap-like (iSWAP-like) gate to attain an arbitrary swap angle, theta, and a controlled-phase gate that generates an arbitrary conditional phase, phi. Using one of each of these gates, we can perform an arbitrary two-qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic simulation (fSim) gate set. We benchmark the fidelity of the iSWAP-like and controlled-phase gate families as well as 525 other 'Sim gates spread evenly across the entire tSim(theta, phi) parameter space, achieving a purity-limited average two-qubit Pauli error of 3.8 x 10(-3) per fSim gate.