Residual-ZZ-coupling suppression and fast two-qubit gate for Kerr-cat qubits based on level-degeneracy engineering

IF 3.6 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters Pub Date : 2025-01-29 DOI:10.1063/5.0241315

Takaaki Aoki, Akiyoshi Tomonaga, Kosuke Mizuno, Shumpei Masuda

引用次数: 0

Abstract

Building large-scale quantum computers requires an interqubit-coupling scheme with a high on–off ratio to avoid unwanted crosstalk coming from residual coupling and to enable fast multi-qubit operations. We propose a ZZ-coupling scheme for two Kerr-cat qubits with a frequency-tunable coupler. By making four relevant states of the two Kerr-cat qubits quadruply degenerate, we can switch off the ZZ coupling. By partially lifting the level degeneracy, we can switch it on. We theoretically show that an experimentally feasible circuit model suppresses the residual ZZ coupling. Moreover, our circuit can realize RZZ(−π/2)-gate fidelity higher than 99.9% within 18 ns when decoherence is ignored. Our model includes the first-order terms in expansion beyond the rotating-wave approximation.

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基于水平简并工程的Kerr-cat量子比特残差耦合抑制和快速双量子位门

构建大规模量子计算机需要一种具有高开关比的量子比特间耦合方案，以避免残留耦合产生的不必要的串扰，并实现快速的多量子比特运算。我们提出了一种具有频率可调谐耦合器的两个Kerr-cat量子比特的zz耦合方案。通过使两个Kerr-cat量子比特的四个相关态四重简并，我们可以关闭ZZ耦合。通过部分提升能级简并，我们可以开启它。我们从理论上证明了一种实验上可行的电路模型可以抑制残余ZZ耦合。在不考虑退相干的情况下，我们的电路可以在18ns内实现99.9%以上的RZZ（−π/2）栅极保真度。我们的模型包括了在旋转波近似之外展开的一阶项。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Physics Letters 物理-物理：应用

CiteScore

6.40

自引率

10.00%

发文量

1821

审稿时长

1.6 months

期刊介绍： Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology. In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics. APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field. Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.