Optimized cross-resonance gate for coupled transmon systems
Optimized cross-resonance gate for coupled transmon systems
复制标题
用于耦合传输系统的优化交叉谐振门
DOI：
10.1103/physreva.97.042348
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发表时间：
2017
影响因子：
2.9
通讯作者：
F. Wilhelm
中科院分区：
文献类型：
--
作者：
S. Kirchhoff;T. Keßler;Per J. Liebermann;E. Ass'emat;S. Machnes;F. Motzoi;F. Wilhelm
交叉共振门是针对不可调谐量子比特而引入的一种固定频率超导量子比特纠缠门。虽然简单且可扩展，但它存在持续时间长和保真度有限的问题。采用两种不同的最优控制算法，探讨了该系统中CNOT门的量子速度极限。我们证明了接近这个极限的能力在很大程度上取决于用来描述最优控制脉冲的函数。单载流子的分段常数ansatz导致实验上可行的脉冲形状，比目前实验中使用的脉冲形状短，但距离速度限制仍然相对较远。另一方面，基于最优控制问题中涉及的两个主要频率的ansatz允许在30$ns以下以两倍以上的速度生成最优解。这接近理论量子速度极限，我们估计典型电路qed参数为15$ns，这比当前实验微波驱动的实现快一个数量级，是可调谐直接耦合实验实现的两倍多。
The cross-resonant gate is an entangling gate for fixed frequency superconducting qubits introduced for untunable qubits. While being simple and extensible, it suffers from long duration and limited fidelity. Using two different optimal control algorithms, we probe the quantum speed limit for a CNOT gate in this system. We show that the ability to approach this limit depends strongly on the ansatz used to describe the optimal control pulse. A piecewise constant ansatz with a single carrier leads to an experimentally feasible pulse shape, shorter than the one currently used in experiments, but that remains relatively far from the speed limit. On the other hand, an ansatz based on the two dominant frequencies involved in the optimal control problem allows to generate an optimal solution more than twice as fast, in under $30$ns. This comes close to the theoretical quantum speed limit, which we estimate at $15$ns for typical circuit-QED parameters, which is more than an order of magnitude faster than current experimental microwave-driven realizations, and more than twice as fast as tunable direct-coupling experimental realizations.
影响因子：
8.6
作者：
Caneva, T.;Murphy, M.;Santoro, G. E.
通讯作者：
Santoro, G. E.
影响因子：
2.9
作者：
Machnes, S.;Sander, U.;Schulte-Herbrueggen, T.
通讯作者：
Schulte-Herbrueggen, T.