AI 中文总结
研究针对囚禁离子光学量子比特激光相位噪声问题，开发基于庞德-德雷弗-霍尔前馈方法的有源相位噪声稳定系统，用光纤电光调制器和电前馈伺服抑制噪声，提升相干时间，且该技术易适配其他光学量子比特。
AI 中文摘要
激光相位噪声是决定囚禁离子量子系统中门保真度和相干时间的限制因素之一。先前研究表明，当离子量子比特的拉比频率接近伺服凸起相位噪声频率时，驱动激光会限制保真度和相干时间。通常通过选择伺服凸起区域之外的拉比频率来缓解此问题，但这限制了门速度的可用范围并可能限制可实现的保真度。为解决此问题，我们为1762nm的钡离子光学量子比特激光器开发了一种有源相位噪声稳定系统，采用带有电前馈伺服的光纤电光调制器（EOM）。结果表明，基于庞德-德雷弗-霍尔（PDH）前馈方法的此设置，在锁定系统中可在凸起峰值频率附近将伺服凸起相位噪声抑制15dB。使用延迟自外差干涉测量法（DSHI）分析激光相位噪声。我们还在光学量子比特上测试了稳定化激光，基于拉比振荡的测量幅度衰减观察到相干时间有明显改善，即使拉比频率处于伺服凸起带宽内。该技术稍作修改就能很容易地应用于其他光学量子比特。
英文摘要
Laser phase noise is one of the limiting factors that dictate gate fidelities and coherence times in trapped-ion quantum systems. Previous studies have reported that when the Rabi frequency of an ion qubit is close to the servo-bump phase-noise frequency, the driving laser limits the fidelity and coherence time. This issue has typically been mitigated by choosing a Rabi frequency outside the servo-bump region. However, this constrains the usable range of gate speeds and can limit the achievable fidelity. To address this issue, we developed an active phase-noise stabilization system for a barium-ion optical-qubit laser at 1762 nm, employing a fiber electro-optic modulator (EOM) with an electrical feedforward servo. Our results demonstrate that this setup, based on the Pound-Drever-Hall (PDH) feedforward method, can suppress servo-bump phase noise by 15 dB near the bump peak frequency in our locking system. The laser phase noise is analyzed using delayed self-heterodyne interferometry (DSHI). We further tested the stabilized laser on an optical qubit and observed a clear improvement in coherence time based on the measured amplitude decay of Rabi oscillations, even when the Rabi frequency lies within the servo-bump bandwidth. This technique can be readily adapted to other optical qubits with minimal modifications.
Comments16 pages, 5 figures
