[论文解读] Highly multimode visible squeezed light with programmable spectral correlations through broadband up-conversion

Federico Presutti, Logan G. Wright+5 more|arXiv (Cornell University)|Jan 11, 2024

Photorefractive and Nonlinear Optics被引用 4

一句话总结

本文展示了通过宽带绝热频率转换（AFC）将红外压缩态转换至可见光谱，生成具有超过400个频率模式、每脉冲约700个光子的高多模可见压缩光。该方法可程序化调控其光谱关联，实现高效、高保真度的单台EMCCD相机测量，为可扩展的频率编码量子信息处理提供紧凑、低资源的实现路径。

ABSTRACT

Multimode squeezed states of light have been proposed as a resource for achieving quantum advantage in computing and sensing. Recent experiments that demonstrate multimode Gaussian states to this end have most commonly opted for spatial or temporal modes, whereas a complete system based on frequency modes has yet to be realized. Instead, we show how to use the frequency modes simultaneously squeezed in a conventional, single-spatial-mode, optical parametric amplifier when pumped by ultrashort pulses. Specifically, we show how adiabatic frequency conversion can be used not only to convert the quantum state from infrared to visible wavelengths, but to concurrently manipulate the joint spectrum. This near unity-efficiency quantum frequency conversion, over a bandwidth >45 THz and, to our knowledge, the broadest to date, allows us to measure the state with an electron-multiplying CCD (EMCCD) camera-based spectrometer, at non-cryogenic temperatures. We demonstrate the squeezing of >400 frequency modes, with a mean of approximately 700 visible photons per shot. Our work shows how many-mode quantum states of light can be generated, manipulated, and measured with efficient use of hardware resources -- in our case, using one pulsed laser, two nonlinear crystals, and one camera. This ability to produce, with modest hardware resources, large multimode squeezed states with partial programmability motivates the use of frequency encoding for photonics-based quantum information processing.

研究动机与目标

• 通过多模压缩光实现完全基于频率模式的连续变量量子系统。
• 解决在可见光谱中检测与操控高带宽、多模量子态的挑战。
• 展示高效、高吞吐量的量子频率转换，同时保持并控制光谱关联。
• 利用一台激光器、两块晶体和一台相机，实现大规模多模高斯量子态的实用化、低资源实现。

提出的方法

• 使用简并光学参量放大器（DOPA）在1550 nm波段的近红外波段生成高度多模压缩真空态。
• 利用1033 nm泵浦光进行宽带绝热频率转换（AFC），将压缩态转换至可见光波段（620 nm），同时保持量子关联。
• 通过整形泵浦光的时频轮廓，控制输出态的联合光谱结构，实现光谱关联的可编程调控。
• 利用频率分辨电子倍增CCD（EMCCD）相机测量最终态，该相机可在离散频率通道中检测光子计数。
• 采用线性酉变换与协方差矩阵建模系统，描述从红外模式到可见模式的量子态演化过程。
• 通过探测器效率和暗计数率参数，将实验结果与经典可模拟性边界进行对比，评估量子优势潜力。

Figure 4: Preparing the joint spectrum via frequency conversion. By pulse shaping the AFC pump $A(\omega_{\text{p}})$ , we can modify the linear unitary transformation $U$ performed by the AFC process, hence the state and the measured spectral photon-number correlations. The pump spectral intensity

实验结果

研究问题

• RQ1 能否通过宽带频率转换生成具有可编程光谱关联的高多模可见压缩光？
• RQ2 绝热频率转换在多模压缩态中能在多大程度上保持并控制纠缠结构？
• RQ3 基于EMCCD的频率分辨光子计数能否实现在非低温条件下对大规模多模量子态的高保真度、高吞吐量测量？
• RQ4 泵浦带宽如何影响转换后多模态态的连通性与纠缠结构？
• RQ5 在使用具有真实探测器参数的EMCCD相机时，高斯玻色采样中量子优势的实际极限是什么？

主要发现

• 实验成功生成了超过400个频率模式的可见压缩光，每脉冲平均光子数约为700个。
• 宽带绝热频率转换的转换带宽超过45 THz，为迄今最宽。
• 通过泵浦整形实现了对光谱关联的完全控制，可编程调控联合光谱结构。
• 仅使用一台EMCCD相机即实现室温下的频率分辨光子计数，避免了低温冷却。
• 模拟结果表明，泵浦带宽直接影响纠缠连通性，更宽的泵浦可实现更复杂的纠缠结构。
• 在使用真实EMCCD参数时，实验设置仍处于经典可模拟性边界之外，支持高斯玻色采样中实现量子优势的潜力。

Figure A5: Photographs of the Experiment. The beam paths are overlaid. Beam color to wavelength legend: H TML]00CCCC 1550 H TML]996185 1033 H TML]AE4132 775 H TML]FFA500 620 H TML]82B366 516 nm. a. Pulse shaper. b. DOPA. c. AFC. d. Spectrometer. e. 775 nm pump generation. f. Monochromation and coinc