Name: generation and coherent control of pulsed quantum frequency combs
Uploaded: 2018-06-08T13:00:00.000+00:00
Duration: 6 min 42 s
Description: Watch this Scientific Journal Video about Generation and Coherent Control of Pulsed Quantum Frequency Combs at JoVE.com

我们感谢 r. Helsten 的技术洞察力;p 从 QPS Photronics 的帮助和加工设备;以及 QuantumOpus 和 n 贝尔托光电元件的支持和为我们提供最先进的光子检测设备。这项工作是由下列资金来源作出的: 加拿大自然科学和工程研究理事会 (NSERC) (Steacie、战略、发现和加速赠款计划、Vanier 加拿大研究生奖学金、USRA 奖学金);Mitacs (IT06530) 和 PBEEE (207748);MESI SIIRI 倡议;加拿大研究椅项目;澳大利亚研究委员会发现项目 (DP150104327);欧洲联盟的地平线2020在玛丽玛丽·斯卡洛多斯卡·居里-居里赠款下的研究和创新计划 (656607);(城大 SRG-Fd 计划 (7004189);中国科学院战略优先研究项目 (XDB24030300);欧洲联盟 FP7 方案 INCIPIT (PIOF-GA-2013-625466) 下的《人民方案》 (居里夫人行动);俄罗斯联邦政府通过 ITMO 研究金和教授方案 (赠款 074-U 01);1000人才四川项目 (中国)

1. 通过脉冲激发产生高维频率-bin 纠缠态
<ol><li>按照图 2 (生成阶段) 中概述的方案, 使用偏振维护光纤连接每个组件 (以改善环境稳定性)。</li>
	<li>将电源连接到电光振幅调制器, 并应用直流电压偏移, 调整偏移值, 直到通过它传输的光功率大约减半 (使用光功率计测量), 如峰值2兆瓦的传输值被减半到1兆瓦。</li>
	<li>测量近似的外腔长度。使用关系计算外部腔模式间距, <img alt="Equation 07" src="/files/ftp_upload/57517/57517eq07v3.jpg"> 在<img alt="Equation 08" src="/files/ftp_upload/57517/57517eq08v3.jpg">哪里是外腔模间距, c是光在真空中的速度, <img alt="Equation 09" src="/files/ftp_upload/57517/57517eq09v3.jpg">是腔介质的有效指标, L是外腔长度。例如, 对于由光纤组成的20米腔, 其有效折射率为 1.46, 近似腔模间距为 10.2 MHz。</li>
	<li>打开放大光纤, 启动激光。</li>
	<li>将快速光电二极管插入到安装中的腔耦合器或其他环形端口。将光电二极管信号与示波器连接, 观察励磁场在时域内的强度。</li>
	<li>将示波器时间分辨率设置为 < 100 ps (通过水平刻度旋钮), 以解决 ns 级的脉冲。在这一步, 如果没有调制器激活, 示波器上的输出将显示低质量, 高噪声脉冲列车不稳定的脉冲操作。</li>
	<li>将函数发生器连接到电光振幅调制器。将函数发生器输出的频率设置为上面找到的 (近似) 外部腔模式间距 (或其谐波)。此信号执行锁模。选择脉冲 (矩形) 波形或正弦波进行振幅调制。打开函数生成器。</li>
	<li>调谐射频函数发生器频率和直流偏移, 以优化和稳定示波器上的脉冲列车形状。如果使用脉冲驱动信号, 则优化其工作周期。</li>
	<li>手动调整光纤放大增益, 以减少 (或增加) 脉冲强度的制度, 如所产生的光子的性质是由用户所期望的 (汽车是一个有用的指标在这里-见下文了解其测量的细节)。为此, 比较与定时电子附带的可视界面生成的相应的重合直方图。</li>
	<li>用脉冲列车信号 (光电二极管检测到) 或射频锁模信号将定时电子同步通道与光子对生成同步单光子探测器。</li>
	<li>为了提高 QFCs 的生成速率, 在外腔频率间距较高的谐波下驱动锁模调制器, 同时增大放大器增益以确保每脉冲的功率相同-这维护了光子对车, 而提高对生产率 (图 3)。为此, 分别增加了函数发生器输出频率和放大器增益。</li>
</ol>2. 高维频率-bin 纠缠态的控制
<ol><li>按照图 2 (控制阶段) 中概述的方案, 使用偏振维护光纤连接所有组件。从该生成方案中的陷波滤波器开始, 串联第一个可编程滤波器、相位调制器和第二可编程滤波器。最后连接单光子探测器进行测量。</li>
	<li>可编程滤波器操作 注: 根据所执行的具体应用/测量结果, QFC 的控制参数会有所不同, 并且必须相应地确定适用于频率模式的相位和振幅掩码。振幅掩模可用于衰减或阻挡某些频率模式, 相位掩模可以在每个模式上传递任意的相移。<ol>
<li>确定所需的应用程序/测量所需的掩码。</li>
		<li>通过可编程滤波器视觉接口22, 设置所需频率模式通道的振幅, 并衰减所有其他。</li>
		<li>同样, 应用相位掩码 (适用于不想要的通道的相位不重要, 因为它们完全衰减)。用视觉接口控制可编程滤波器, 其中选择所需频率。</li>
	</ol></li>
	<li>相位调制操作
	<ol>
<li>采用相位调制, 由周期性信号驱动, 将每个光谱分量分割成侧频带, 均匀地间隔在驱动相位调制器的信号发生器的频率上。利用这种方法混合几种不同的量子频率模式, 类似于路径纠缠方案中的空间波束分配器。在量子体制中, 电光相位调制被认为是量子散射运算23。</li>
		<li>确定目标频率模式 (依赖于<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">和测量/处理正在执行), 并计算电压模式 (正弦波发生器的频率和振幅), 以优化所需<img alt="Equation 10" src="/files/ftp_upload/57517/57517eq10v3.jpg">的值 (见下面的一些详情)。</li>
		<li>使用低损耗电缆 (如 SMC 电缆) 将信号发生器连接到 RF 放大器。将射频放大器输出连接到相位调节器, 也使用适当的射频电缆。一旦所有射频端连接并正确终止, 偏置射频放大器。</li>
		<li>确保 RF 放大器有足够的输出功率, 以驱动光电相位调制器, 具有足够的电压, 以满足所需的混合条件-这些都是在<img alt="Equation 11" src="/files/ftp_upload/57517/57517eq11v3.jpg">几个 (相位调制器的半波电压) 的顺序。另外, 要确保射频电缆和连接器足够的带宽和频率范围的驱动信号。</li>
		<li>设置射频信号发生器 (驱动相位调制器) 的频率, 这将重叠所需的模式与创建的侧带 (e., 33 GHz)。</li>
		<li>打开信号发生器以混合频率模式。</li>
		<li>为了验证是否应用了正确的调制方式, 通过相位调制器发送连续波激光器, 并检查输出频谱是否对应于使用光学频谱分析仪的预期调制 (调制参数可进一步已优化, 请参阅备注)。 注: 优化频率模式的混合 (确定最佳函数频率和振幅), 高度依赖于所需的混合方案、进行的实验和状态维<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">数。如果可能, 混合方案应混合模式接近初始频率模式 (在低整数边), 以提高混合效率。例如, 如果<img alt="Equation 12" src="/files/ftp_upload/57517/57517eq12v3.jpg">建议混合发生在两种频率模式之间的中途 (因此, 相位调制应在频率上驱动, 其整数倍数等于量子模式频率间距的一半, 或自由光谱范围 (FSR))。但是, 对于<img alt="Equation 13" src="/files/ftp_upload/57517/57517eq13v3.jpg"> </img>, 建议在中心频率模式下进行混合 (相位调制应在频率上驱动, 整数倍数等于 FSR)。例如, 带<img alt="Equation 13" src="/files/ftp_upload/57517/57517eq13v3.jpg">和微腔<img alt="Equation 14" src="/files/ftp_upload/57517/57517eq14v3.jpg"> GHz, 相位调制驱动信号设置为 33.33 GHz <img alt="Equation 15" src="/files/ftp_upload/57517/57517eq15v3.jpg"> , 使边带与相邻频率模式重叠, 同时在中心留下足够的强度频率模式。这将导致<img alt="Equation 16" src="/files/ftp_upload/57517/57517eq16v3.jpg">边相邻模式的重叠, <img alt="Equation 17" src="/files/ftp_upload/57517/57517eq17v3.jpg">并<img alt="Equation 18" src="/files/ftp_upload/57517/57517eq18v3.jpg">在中心频率模式下<img alt="Equation 17" src="/files/ftp_upload/57517/57517eq17v3.jpg">进行。图 4a可视化了调制过程和边带系数的例子。每个频率模式经历相同的相位调制, 并创建相同的边带分布, 但以原始频率模式为中心 (图 4a)。对于单频模式, 边带振幅计算为傅里叶级数24的系数, <img alt="Equation 19" src="/files/ftp_upload/57517/57517eq19v3.jpg"> 当<img alt="Equation 10" src="/files/ftp_upload/57517/57517eq10v3.jpg">相位调制器被驱动的<img alt="Equation 20" src="/files/ftp_upload/57517/57517eq20v3.jpg">频率, 是相位<img alt="Equation 21" src="/files/ftp_upload/57517/57517eq21v3.jpg">调节模式 (周期性与频率<img alt="Equation 21" src="/files/ftp_upload/57517/57517eq21v3.jpg"> </img>) <img alt="Equation 23" src="/files/ftp_upload/57517/57517eq23v3.jpg">时, 将振幅<img alt="Equation 22" src="/files/ftp_upload/57517/57517eq22v3.jpg">转移到 th 边带, 是周期调制函数的参数 (<img alt="Equation 24" src="/files/ftp_upload/57517/57517eq24v3.jpg">)。对于正弦驱动信号, <img alt="Equation 25" src="/files/ftp_upload/57517/57517eq25v3.jpg">侧频带振幅由雅各比-愤怒膨胀描述, <img alt="Equation 26" src="/files/ftp_upload/57517/57517eq26v3.jpg"> <img alt="Equation 27" src="/files/ftp_upload/57517/57517eq27v3.jpg"> <img alt="Equation 20" src="/files/ftp_upload/57517/57517eq20v3.jpg">在<img alt="Equation 28" src="/files/ftp_upload/57517/57517eq28v3.jpg">哪一阶贝塞尔函数的第一种计算在<img alt="Equation 29" src="/files/ftp_upload/57517/57517eq29v3.jpg">和<img alt="Equation 30" src="/files/ftp_upload/57517/57517eq30v3.jpg">是最大相移 (其中<img alt="Equation 31" src="/files/ftp_upload/57517/57517eq31v3.jpg">是电压振幅的单音调驱动信号)。</li>
	</ol></li>
</ol>3. 高维频率-bin 纠缠态的处理
<ol><li>单光子光谱
	<ol>
<li>在可编程滤波器的输出中, 在 QFC 的励磁场过滤后插入一个光子探测器。</li>
		<li>通过可编程滤波器的计算机软件, 扫过全可编程滤波器带宽, 使用窄带带通滤波器振幅掩模, 测量光子计数率作为频率函数。例如, 如果使用 MATLAB 中的可视化接口/控件脚本 (与可编程的过滤器控件和定时电子连接), 请输入所需的筛选器带宽值和步骤编号, 然后单击 "运行"。确保足够的集成时间以获得正确的光子计数。</li>
		<li>要从这些数据中重建光谱, 请用 Matlab 脚本 (例如, 使用一个) 将光子计数率与相应的波长 (带通滤波器中心) 相对应。</li>
	</ol></li>
	<li>巧合测量
	<ol>
<li>为了完成一个巧合测量, 分裂和路由信号和滚轮光子分离单光子探测器。如果可编程过滤器有多个端口, 请使用它来执行分离。否则, 在单光子探测器之前插入密集波长分复用器 (DWDM), 并使用此方法来传送光子。</li>
		<li>使用可编程滤波器 (通过提供的软件接口) 选择一个信号和滚轮对 (例如, 与激发频率、signal-2 和 idler-2 有关的第二共振线), 并将它们路由到两个单独的单光子探测器。例如, 对于 WaveManager 软件, 单击 Flexgrid 子菜单, 单击 "添加", 然后输入所选通道22的波长和输出端口。</li>
		<li>使用时间到数字转换器记录信号和滚轮光子的到达时间。从这些测量中, 计算两个光子之间的时间延迟。绘制一个直方图 (例如, 使用 Matlab 脚本) 的巧合计数的时间延迟<img alt="Equation 32" src="/files/ftp_upload/57517/57517eq32v3.jpg">之间的信号和滚轮-这提供了一个巧合的测量。 注意: 汽车公制比较了产生的光子对的真实重合数与由多光子过程和暗计数引起的意外巧合计数的数量。</li>
		<li>从上述计算的测量中, 记录中心峰中的计数数 (在同一个脉冲中产生的巧合, 以零延迟为中心<img alt="Equation 33" src="/files/ftp_upload/57517/57517eq33v3.jpg"> </img>)-这是重合值。</li>
		<li>记录每个边峰中的平均计数 (不同脉冲产生的光子的巧合, 其中<img alt="Equation 32" src="/files/ftp_upload/57517/57517eq32v3.jpg">是脉冲训练周期的倍数, 即脉冲重复速率的逆), 这是意外值。 注: 这辆车只不过是这两个值的比值 (巧合值/意外值)。</li>
	</ol></li>
	<li>密度矩阵重建 注: 密度矩阵重建的过程取决于量子态的几个参数: 光子的维数、光子的数量以及测量的模式。所需的原始测量数等于<img alt="Equation 34" src="/files/ftp_upload/57517/57517eq34v3.jpg">, 其中<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">是维度和<img alt="Equation 35" src="/files/ftp_upload/57517/57517eq35v3.jpg">是光子的数量。例如, 一个具有维数的双光子对<img alt="Equation 13" src="/files/ftp_upload/57517/57517eq13v3.jpg">将需要81测量。本协议将概述密度矩阵重建的一般过程, 并举例说明一对<img alt="Equation 13" src="/files/ftp_upload/57517/57517eq13v3.jpg">频率模式光子。<ol><li>为所需状态和一组投影向量确定一组基准向量 (有关如何适当选择这些的详细信息, 请参见下面的内容)。</li>
		<li>以巧合测量, 使用可编程的过滤器或 DWDM 路线信号和滚轮光子分离单一光子探测器。</li>
		<li>通过可编程滤波器软件控制, 选择所需的频率模式, 并衰减所有其他。设置相位掩码值以单独实现每个投影 wavevector 并记录一个重合度测量。在不同的投影重合计数之间允许相同的积分时间是很重要的。</li>
		<li>使用自定义计算机脚本, 计算每个投影 wavevector 的原始重合计数测量光子的密度矩阵 (有关计算细节见下文)。 注: 在确定密度矩阵测量的基向量时, 它们必须跨越状态空间。对于示例案例, 基向量是 <img alt="Equation 36" src="/files/ftp_upload/57517/57517eq36v3.jpg"> 对于状态<img alt="Equation 37" src="/files/ftp_upload/57517/57517eq37v3.jpg"> </img>, 密度矩阵描述量子状态, <img alt="Equation 38" src="/files/ftp_upload/57517/57517eq38v3.jpg"> 任何真实的物理系统的密度矩阵必须是一个正定的, 埃尔米特矩阵-但由于噪音, 这可能并不总是这样。在例子事例以选择的依据, wavevector 为理想最大地频率纠缠的状态可以代表作为 <img alt="Equation 39" src="/files/ftp_upload/57517/57517eq39v3.jpg"> 因此, 理论密度矩阵是: <img alt="Equation 40" src="/files/ftp_upload/57517/57517eq40v3.jpg"> 投影测量是在一系列的投影 wavevectors 上拍摄的<img alt="Equation 41" src="/files/ftp_upload/57517/57517eq41v3.jpg"> </img>。每一个投射的重合计数被给作为, <img alt="Equation 42" src="/files/ftp_upload/57517/57517eq42v3.jpg"> 哪里<img alt="Equation 43" src="/files/ftp_upload/57517/57517eq43v3.jpg">是常量 (请参见下面的定义)。</li>
		<li>选择一组正交的<img alt="Equation 44" src="/files/ftp_upload/57517/57517eq44v3.jpg"> </img>、归一化<img alt="Equation 45" src="/files/ftp_upload/57517/57517eq45v3.jpg">的矩阵, 这样 <img alt="Equation 46" src="/files/ftp_upload/57517/57517eq46v3.jpg"> 哪里<img alt="Equation 47" src="/files/ftp_upload/57517/57517eq47v3.jpg">是痕迹, <img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">是维度, <img alt="Equation 35" src="/files/ftp_upload/57517/57517eq35v3.jpg">是光子的数量, <img alt="Equation 48" src="/files/ftp_upload/57517/57517eq48v3.jpg">是克罗内克三角洲函数。这些矩阵可以使用特殊的酉 SU (<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">) 生成器 (其中有<img alt="Equation 49" src="/files/ftp_upload/57517/57517eq49v3.jpg"> </img>), 连同标识矩阵, 通过所有可能的张量乘积组合25来构造。请参见下面的示例案例的正交矩阵。</li>
		<li>通过以下关系重构<img alt="Equation 50" src="/files/ftp_upload/57517/57517eq50v3.jpg">密度矩阵, <img alt="Equation 51" src="/files/ftp_upload/57517/57517eq51v3.jpg"> <img alt="Equation 52" src="/files/ftp_upload/57517/57517eq52v3.jpg"> <img alt="Equation 53" src="/files/ftp_upload/57517/57517eq53v3.jpg"> <img alt="Equation 54" src="/files/ftp_upload/57517/57517eq54v3.jpg"> 在<img alt="Equation 55" src="/files/ftp_upload/57517/57517eq55v3.jpg">哪里是光子<img alt="Equation 56" src="/files/ftp_upload/57517/57517eq56v3.jpg">计数的投影向量, <img alt="Equation 57" src="/files/ftp_upload/57517/57517eq57v3.jpg">是投影向量 (见下一步), 在哪里<img alt="Equation 58" src="/files/ftp_upload/57517/57517eq58v3.jpg"> , 并<img alt="Equation 59" src="/files/ftp_upload/57517/57517eq59v3.jpg">根据等式定义计算。 注: 示例案例的投影 wavevectors 是, <img alt="Equation 60" src="/files/ftp_upload/57517/57517eq60v3.jpg"><img alt="Equation 61" src="/files/ftp_upload/57517/57517eq61v3.jpg"> <img alt="Equation 62" src="/files/ftp_upload/57517/57517eq62v3.jpg"> <img alt="Equation 63" src="/files/ftp_upload/57517/57517eq63v3.jpg"> <img alt="Equation 64" src="/files/ftp_upload/57517/57517eq64v3.jpg"> <img alt="Equation 65" src="/files/ftp_upload/57517/57517eq65v3.jpg"> <img alt="Equation 66" src="/files/ftp_upload/57517/57517eq66v3.jpg"> <img alt="Equation 67" src="/files/ftp_upload/57517/57517eq67v3.jpg"> <img alt="Equation 68" src="/files/ftp_upload/57517/57517eq68v3.jpg"> 实验中, 通过可编程滤波器在每个模态上传递适当的相移, 实现了这些 wavevectors。有关投影向量的讨论, 请参阅以前的出版物25 。矩阵的正交集合, <img alt="Equation 69" src="/files/ftp_upload/57517/57517eq69v3.jpg">对于示例用例, 首先使用 SU (3) 生成器与标识矩阵一起选择, <img alt="Equation 70" src="/files/ftp_upload/57517/57517eq70v3.jpg"> <img alt="Equation 71" src="/files/ftp_upload/57517/57517eq71v3.jpg"> <img alt="Equation 72" src="/files/ftp_upload/57517/57517eq72v3.jpg"> <img alt="Equation 73" src="/files/ftp_upload/57517/57517eq73v3.jpg"> <img alt="Equation 74" src="/files/ftp_upload/57517/57517eq74v3.jpg"> <img alt="Equation 75" src="/files/ftp_upload/57517/57517eq75v3.jpg"> <img alt="Equation 76" src="/files/ftp_upload/57517/57517eq76v3.jpg"> <img alt="Equation 77" src="/files/ftp_upload/57517/57517eq77v3.jpg"> <img alt="Equation 78" src="/files/ftp_upload/57517/57517eq78v3.jpg"> 并计算为, <img alt="Equation 79" src="/files/ftp_upload/57517/57517eq79v3.jpg">
</li>
		<li>有关高维状态重建的更深入的讨论, 请参阅参考 25 25。</li>
	</ol></li>
</ol>

<ol>
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光频域, 通过 QFCs, 在量子应用中是有利的, 原因很多。操作是全局的, 同时对所有状态执行, 这会导致在状态维度增加时不会扩展大小或复杂性的设计。随着组件可以在不改变安装的情况下进行重新配置, 并且能够通过开发现有的和/或开发的半导体和电信基础设施集成到芯片上, 这一点得到了加强。其他光学微腔的生成技术也可以采用, 如二阶非线性微腔28、微盘<sup class="xref...

量子现象的控制为在安全量子通信1、强大的量子信息处理2和量子传感3等不同领域的新应用开辟了可能性。虽然各种物理平台正在积极研究实现量子技术4, 光量子态是重要的候选, 因为它们可以表现出长期的相干时间和稳定性从外部噪音, 优秀传输特性, 以及与现有通信和硅片 (CMOS) 技术的兼容性。
为了充分实现量子技术中光子的潜能, 通过使用多个纠缠方和/或高维度, 可以提高状态复杂性和信息内容。然而, 这种光学状态的芯片生成缺乏实用性, 因为设置是复杂的, 不是完全可伸缩的, 和/或使用高度专门化的组件。具体来说, 高维路径纠缠需要<img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">一致激发的相同源和复杂的光束分配器5 ( <img alt="Equation 01" src="/files/ftp_upload/57517/57517eq01v3.jpg">状态维度) 电路, 而时间纠缠需要复杂的多臂干涉仪6。值得注意的是, 频域非常适合于复杂状态的可伸缩生成和控制, 如最近在量子频率梳 (QFC)7,8中利用集成光学和电信基础设施9, 为未来的量子信息技术提供了一个有希望的框架。
在集成微腔中利用非线性光学效应产生了片上 QFCs。使用这样一个非线性微谐振器, 两个纠缠光子 (称为信号和滚轮) 是由自发的四波混合产生, 通过湮灭两个励磁光子-与产生的一对叠加的腔的结果对均匀间隔的谐振频率模式 (图 1)。如果单个频率模式之间存在一致性, 则形成10的频率-bin 纠缠态, 通常称为锁模两光子状态11。这个状态波函数可以描述,
<img alt="Equation 02" src="/files/ftp_upload/57517/57517eq02v3.jpg">
在这里<img alt="Equation 03" src="/files/ftp_upload/57517/57517eq03v3.jpg"> , <img alt="Equation 04" src="/files/ftp_upload/57517/57517eq04v3.jpg">分别是单频模式的滚轮和信号分量, 并且<img alt="Equation 05" src="/files/ftp_upload/57517/57517eq05v3.jpg">是 th 信号-滚轮模式对的概率<img alt="Equation 06" src="/files/ftp_upload/57517/57517eq06v3.jpg">振幅。
以前的芯片 QFCs 演示强调了它们作为可行的量子信息平台的通用性, 包括相关光子12、交叉极化光子13、纠缠光子14、15的梳子。,16、多光子状态15、频率-bin 纠缠态9、17。在这里, 我们提供了一个详细的概述 QFC 平台和一个协议的高维频率-bin 纠缠光学状态产生和控制。
未来的量子应用, 特别是那些与高速电子接口 (为了及时信息处理), 要求高纯度的光子状态的高速度生成在紧凑和稳定的设置。我们使用一个主动锁模, 嵌套腔方案, 以产生 QFCs 在电信, C 和 L 频段。微环被并入一个较大的脉冲激光腔内, 光增益 (由掺铒光纤放大器提供) 过滤, 以匹配微环励磁带宽18。锁模是通过对腔体损耗19的电光调制来积极实现的。隔离器确保脉冲传播跟随一个方向。所产生的脉冲列车具有很低的根平均平方 (RMS) 噪声, 并具有可调谐的重复率和脉冲功率。高隔离陷波滤波器将发射的 QFC 光子与励磁场分离开来。这些单光子然后引导通过纤维进行控制和检测。
我们的计划是迈向高世代率, 小脚印 QFC 源, 因为所有使用的组件可能会集成到一个光子芯片上。此外, 脉冲激励特别适合量子应用。首先, 看一双与励磁对称的微谐振腔共振, 它产生双光子状态, 每个光子的特征为线性光量子计算20的单频 mode–中心。同样, 多光子状态可以通过移动到更高的功率激励机制和选择多个信号-滚轮对15来产生。第二, 光子在已知的时间窗口中发出, 对应于脉冲励磁, 可以实现后处理和门控, 以改善状态检测。也许最重要的是, 我们的方案支持使用谐波锁模锁定的高频率光子状态, 而不降低巧合-意外比 (汽车)-这可能为高速、多通道量子信息铺平道路。技术。
为了证明频率域的影响和可行性, 必须以有针对性的方式实现对 QFC 状态的控制, 确保高效的转换和状态一致性。为了满足这些要求, 我们使用级联可编程滤波器和相位调制器-在电信行业中建立的组件。可编程滤波器用于在单光子上施加任意的光谱振幅和相位掩码, 分辨率足以单独处理每个频率模式;射频信号发生器驱动的电光相位调制器促进了频率元件21的混合。
该控制方案最重要的方面是, 它使用单一的控制元素, 同时在单一空间模式下对光子的所有量子模式进行操作。增加量子态维度不会导致安装复杂度的增加, 与路径或时间 bin 纠缠方案形成对比。而且, 所有组件都是外部可重构的 (这意味着可以在不修改设置的情况下更改操作) 并使用现有的电信基础结构。因此, 在超快光学处理领域的现有和即将发展可以直接转移到量子态的可伸缩控制的未来。
总之, QFCs 的利用频率域支持复杂量子态的高速率生成及其控制, 因此非常适合于利用复杂的国家实现实用和可伸缩的量子技术。

<table><tbody><tr><td>Superconducting Nanowire Single-Photon Detector System</td><td>Quantum Opus</td><td>Opus One</td><td></td></tr><tr><td>Electro-optic phase modulator</td><td>EO-Space</td><td>Low loss model</td><td></td></tr><tr><td>Programmable filter</td><td>Finisar&amp;nbsp;</td><td>WaveShaper 4000s</td><td></td></tr><tr><td>Timing electronics</td><td>PicoQuant</td><td>HydraHarp 400</td><td></td></tr><tr><td>Micro-ring resonator</td><td></td><td></td><td>200 GHz FSR micro-ring resonator made from high refractive index glass. See Ref. &lt;sup class=&quot;xref&quot;&gt;24&lt;/sup&gt; for platform details.</td></tr><tr><td>Erbium-doped fiber amplifier</td><td>Keopsys</td><td>PEFA-SP-C-PM-27-B202-FA-FA</td><td></td></tr><tr><td>Electro-optic amplitude modulator</td><td>Oclaro&amp;nbsp;</td><td>SD40</td><td></td></tr><tr><td>RF tone source</td><td>Rohde &amp;amp; Schwarz</td><td>SMP 04</td><td></td></tr><tr><td>RF tone amplifier</td><td>RF-Lambda</td><td>RFLUPA27G34GA</td><td></td></tr><tr><td>Function generator</td><td>Tetronix</td><td>AFG 3251</td><td></td></tr><tr><td>Isolator</td><td>General Photonics</td><td>NISO-S-15-SS-FC/APF</td><td></td></tr><tr><td>Oscilloscope</td><td>Tetronix&amp;nbsp;</td><td>TDS5052B</td><td></td></tr><tr><td>Photodiode</td><td>Finisar</td><td>XPDV 50 GHz</td><td></td></tr><tr><td>DWDM</td><td>OptiWorks</td><td>DWFUQUMD08BN</td><td></td></tr><tr><td>Power supply</td><td>Madell</td><td>CA18303D</td><td></td></tr></tbody></table>

generation and coherent control of pulsed quantum frequency combs

提出了一种脉冲量子频率梳的产生和相干操作方法。到目前为止, 由于准备和处理这些状态所需的量子电路越来越复杂, 因此在芯片上以实际方式制备高维状态的方法仍然是难以捉摸的。在这里, 我们概述了如何高维, 频率-bin 纠缠, 双光子状态可以产生在稳定的, 高的产生率, 利用嵌套腔, 主动锁模励磁的非线性微腔。该技术用于产生脉冲量子频率梳。此外, 我们还介绍了如何使用标准通信组件 (如可编程滤波器和电光调制器) 对量子态进行相干操作。具体来说, 我们详细地介绍了如何完成状态表征测量, 如密度矩阵重构, 重合检测和单光子光谱测定。所提出的方法为复杂的高维状态准备和操作协议在频域中形成了一个可访问的、可重构的、可以伸缩的基础。

图 2显示了高维频率-bin 状态的生成和控制 (基于非线性微腔的激发) 的概述方案 (图 1)。此设置使用标准电信组件, 并且在光子生产速率和处理操作应用上具有高度灵活性。图 3显示了通过重合率和汽车作为重复率函数的生成方案的特性, 证明了光子对的生产可以在不减少汽车的情况下增加。在控制部分, 可?...

Watch this Scientific Journal Video about Generation and Coherent Control of Pulsed Quantum Frequency Combs at JoVE.com

Generation and Coherent Control of Pulsed Quantum Frequency Combs

提出了一种利用集成微腔和标准通信组件对高维频率-bin 纠缠光子状态进行实际生成和相干操作的协议。

脉冲量子频率梳的产生与相干控制

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional ...

generation-and-coherent-control-of-pulsed-quantum-frequency-combs

Research

Education

JoVE Core

JoVE Journal

Electrical Engineering

Engineering

Unit 1

Frequency Response

SCIENTISTS IN ACTION

8.9K 次观看.  Institut National de la Recherche Scientifique - Centre Énergie, Matériaux et Télécommunications (INRS-EMT). 提出了一种利用集成微腔和标准通信组件对高维频率-bin 纠缠光子状态进行实际生成和相干操作的协议。

视频: Generation and Coherent Control of Pulsed Quantum Frequency Combs

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

基于微波光子系统回音壁模式谐振器

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

科研

工程学

Quasi-light Storage for Optical Data Packets

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing of the signals is done in the electrical domain. Direct storage in the optical domain would avoid the transfer of the packets to the electrical and back to the optical domain in every network node and, therefore, increase the speed and possibly reduce the energy consumption of telecommunications. However, light consists of photons which propagate with the speed of light in vacuum. Thus, the storage of light is a big challenge. There exist some methods to slow down the speed of the light, or to store it in excitations of a medium. However, these methods cannot be used for the storage of optical data packets used in telecommunications networks. Here we show how the time-frequency-coherence, which holds for every signal and therefore for optical packets as well, can be exploited to build an optical memory. We will review the background and show in detail and through examples, how a frequency comb can be used for the copying of an optical packet which enters the memory. One of these time domain copies is then extracted from the memory by a time domain switch. We will show this method for intensity as well as for phase modulated signals.

The article describes a procedure to store optical data packets with an arbitrary modulation, wavelength, and data rate. These packets are the basis of modern telecommunications.

准光存储光学数据包

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing ...

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.

The gradient echo memory is a protocol for storing optical quantum states of light in atomic ensembles. Quantum memory is a key element of a quantum repeater, which can extend the range of quantum key distribution. We outline the operation of the scheme when implemented in a 3-level atomic ensemble.

梯度回波量子存储在温暖的原子蒸气

Gradient  echo memory (GEM) is a protocol for storing optical quantum states of light in  atomic ensembles. The primary motivation for such a technology ...

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems3. We focus here on the use of a continuous-wave optical parametric oscillator3,4. This system is based on a non-linear &#967;2 crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. 
Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states5. Generating directly such states is a difficult task and would require strong &#967;3 non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

We describe the reliable generation of non-Gaussian states of traveling optical fields, including single-photon states and coherent state superpositions, using a conditional preparation method operated on the non-classical light emitted by optical parametric oscillators. Type-I and type-II phase-matched oscillators are considered and common procedures, such as the required frequency filtering or the high-efficiency quantum state characterization by homodyning, are detailed.

光与连续波光学参量振荡器的量子态工程

Engineering non-classical states of the electromagnetic field is a central quest for quantum optics1,2. Beyond their fundamental significance, such states ...

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

激光驱动的超快分子旋转直接成像

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb ...

化学

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

量子干涉效应在硅谐振环光子源测量

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are degenerated and postselection free. The property of the source is based on the multiple quantum interference effect with a round-trip configuration of a Sagnac interferometer. The quantum interference effects make it possible to use the high generation efficiency of the polarization-entangled photons to process parametric down-conversion, and separate degenerated photon pairs into different optical modes without a postselection requirement. The principle of the optical system was described and experimentally used to measure the fidelity and Bell parameters, and also to characterize the generated polarization-entangled photons from a minimum of six combinations of polarization correlated data. The experimentally obtained fidelity and Bell parameters exceeded the classical local correlation limit and are clear evidence of the generation of unconditional polarization-entangled photons.

We describe an optical system for the generation of unconditional polarization-entangled photons based on multiple quantum interference effects with a detection scheme to estimate the experimental fidelity of generated entangled photons.

基于多重量子干扰生成无条件极化纠缠光子的光子系统

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are ...

Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped fiber laser is built completely using commercially available parts, including $8,000 in fiber optic and pump laser components, plus $4,800 in standard optical components and extra-cavity accessories. Researchers new to fiber optic device fabrication may also consider investing in basic fiber splicing and laser pulse characterization equipment (~$63,000). Important for optimal laser operation, methods to verify true versus apparent (partial or noise-like) mode-locked performance are presented. This system achieves 70 fs pulse duration with a center wavelength of approximately 1,070 nm and a pulse repetition rate of 31 MHz. This fiber laser exhibits the peak performance that may be obtained for an easily assembled fiber laser system, which makes this design ideal for research laboratories aiming to develop compact and portable fs laser technologies that enable new implementations of clinical multiphoton microscopy and fs surgery.

A method is presented to build a custom low-cost, mode-locked femtosecond fiber laser for potential applications in multiphoton microscopy, endoscopy, and photomedicine. This laser is built using commercially available parts and basic splicing techniques.

用于多光子显微镜的全正常分散飞秒光纤激光器的低成本定制制造和模式锁定操作

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped ...

Rapid Repetition Rate Fluctuation Measurement of Soliton Crystals in a Microresonator

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the nonlinearity in a propagation Kerr medium. The development of dissipative Kerr solitons (DKSs) in high-Q microcavities drives a novel, compact, chip-scale soliton source. When DKSs serve as femtosecond pulses, the repetition rate fluctuation can be applied to ultrahigh precision metrology, high-speed optical sampling, and optical clocks, etc. In this paper, the rapid repetition rate fluctuation of soliton crystals (SCs), a special state of DKSs where particle-like solitons are tightly packed and fully occupy a resonator, is measured based on the well-known delayed self-heterodyne method. The SCs are generated using a thermal-controlled method. The pump is a frequency fixed laser with a linewidth of 100 Hz. The integral time in frequency fluctuation measurements is controlled by the length of the delay fiber. For a SC with a single vacancy, the repetition rate fluctuations are ~53.24 Hz within 10 &#181;s and ~509.32 Hz within 125 &#181;s, respectively.

Here, we present a protocol to generate soliton crystals in a butterfly-packaged micro-ring resonator using a thermal tuned method. Further, the repetition rate fluctuations of a soliton crystal with a single vacancy are measured using a delayed self-heterodyne method.

微谐振器中孤子晶体的快速重复率波动测量

Temporal solitons have attracted great interest in the past decades for their behavior in a steady state, where the dispersion is balanced by the ...

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

This is a report on a 100 W, 20 mJ, 1 ps Yb:YAG thin-disk regenerative amplifier. A homemade Yb:YAG thin-disk, Kerr-lens mode-locked oscillator with turn-key performance and microjoule-level pulse energy is used to seed the regenerative chirped-pulse amplifier. The amplifier is placed in airtight housing. It operates at room temperature and exhibits stable operation at a 5 kHz repetition rate, with a pulse-to-pulse stability less than 1%. By employing a 1.5 mm-thick beta barium borate crystal, the frequency of the laser output is doubled to 515 nm, with an average power of 70 W, which corresponds to an optical-to-optical efficiency of 70%. This superior performance makes the system an attractive pump source for optical parametric chirped-pulse amplifiers in the near-infrared and mid-infrared spectral range. Combining the turn-key performance and the superior stability of the regenerative amplifier, the system facilitates the generation of a broadband, CEP-stable seed. Providing the seed and pump of the optical parametric chirped-pulse amplification (OPCPA) from one laser source eliminates the demand of active temporal synchronization between these pulses. This work presents a detailed guide to set up and operate a Yb:YAG thin-disk regenerative amplifier, based on chirped-pulse amplification (CPA), as a pump source for an optical parametric chirped-pulse amplifier.

A protocol for the operation of a high-energy, high-power optical parametric chirped pulse amplifier pump source based on an Yb:YAG thin-disk regenerative amplifier is presented here.

20 mJ，1 ps Yb:YAG薄盘再生放大器

This is a report on a 100 W, 20 mJ, 1 ps Yb:YAG thin-disk regenerative amplifier. A homemade Yb:YAG thin-disk, Kerr-lens mode-locked oscillator with ...