近日，加拿大滑铁卢大学的M. Mariantoni与日本国立信息通信技术研究所的Sahel Ashhab合作并取得一项新进展。他们揭示了驱动多光子量子比特-谐振器相互作用。相关研究成果已于2024年11月19日在国际知名学术期刊《物理评论A》上发表。

该研究团队发展了一套通用理论，用于描述由量子比特驱动增强的多光子量子比特-谐振子相互作用。当驱动接近光子交叉共振时，即量子比特驱动频率是谐振子频率的整数倍时，这种相互作用会在谐振子中产生量子比特条件操作。研究人员特别关注了强驱动情况，此时产生的有效相互作用依赖于量子比特的修饰态。接下来，他们研究了使用双频驱动来构建一个，具有广泛可调有效系统参数的有效多光子拉比哈密顿量，这可能使迄今为止无法实现的新状态得以实现。

，他们讨论了特定情况（即光子数等于2）的应用，这会导致量子比特条件压缩（QCS）。研究人员展示了QCS协议如何通过适当的量子比特测量，来生成正交压缩态的叠加态。研究人员概述了这些态在量子信息处理中的应用，包括通过正交压缩态的叠加在谐振子中编码量子比特。

研究人员还展示了如何利用QCS操作，实现受控压缩门及其在玻色子相位估计中的应用。QCS协议还可以用于在量子比特-谐振子联合希尔伯特空间上，实现更快的幺正算符合成。

最后，研究人员提出了一种基于通过非对称超导量子干涉装置（SQUID）与谐振子耦合的，传输子量子比特的多光子电路量子电动力学（QED）实现方案。研究人员为可以承载上述双光子协议的双光子操作状态，提供了实际的参数估计。通过数值模拟，研究人员表明，即使在存在杂散项和退相干的情况下，本研究的分析预测仍然是稳健的。

附：英文原文

Title: Driven multiphoton qubit-resonator interactions

Author: Mohammad Ayyash, Xicheng Xu, Sahel Ashhab, M. Mariantoni

Issue&Volume: 2024/11/19

Abstract: We develop a general theory for multiphoton qubit-resonator interactions enhanced by a qubit drive. The interactions generate qubit-conditional operations in the resonator when the driving is near -photon cross resonance, i.e., when the qubit drive is times the resonator frequency. We pay special attention to the strong driving regime, where the resulting effective interactions are conditioned on the qubit dressed states. Next, we investigate the use of a two-tone drive to engineer an effective -photon Rabi Hamiltonian with widely tunable effective system parameters, which could enable the realization of new regimes that have so far been inaccessible. Then, we discuss applications for the specific case where =2, which results in qubit-conditional squeezing (QCS). We show that the QCS protocol can be used to generate a superposition of orthogonally squeezed states following a properly chosen qubit measurement. We outline quantum information processing applications for these states, including encoding a qubit in a resonator via the superposition of orthogonally squeezed states. We show how the QCS operation can be used to realize a controlled-squeeze gate and its use in bosonic phase estimation. The QCS protocol can also be utilized to achieve faster unitary operator synthesis on the joint qubit-resonator Hilbert space. Finally, we propose a multiphoton circuit QED implementation based on a transmon qubit coupled to a resonator via an asymmetric SQUID. We provide realistic parameter estimates for the two-photon operation regime that can host the aforementioned two-photon protocols. We use numerical simulations to show that, even in the presence of spurious terms and decoherence, our analytical predictions are robust.

DOI: 10.1103/PhysRevA.110.053711

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.053711