The classic self-referenced frequency comb acts as an unrivaled ruler for precision optical metrology in both time and frequency. Two decades after its invention, the frequency comb is now used in numerous active sensing applications. Many of these applications, however, are limited by the tradeoffs inherent in the rigidity of the comb output and operate far from quantum-limited sensitivity. Here we demonstrate an agile programmable frequency comb where the pulse time and phase are digitally controlled with +/- 2 attosecond accuracy. This agility enables quantum-limited sensitivity in sensing applications since the programmable comb can be configured to coherently track weak returning pulse trains at the shot-noise limit. To highlight its capabilities, we use this programmable comb in a ranging system, reducing the detection threshold by ~5,000-fold to enable nearly quantum-limited ranging at mean pulse photon number of 1/77 while retaining the full accuracy and precision of a rigid frequency comb. Beyond ranging and imaging, applications in time/frequency metrology, comb-based spectroscopy, pump-probe experiments, and compressive sensing should benefit from coherent control of the comb-pulse time and phase.
Programmable ultra-broadband photonic chaos platform enabled by microwave-chaos-driven electro-optic frequency combs
State Key Laboratory of Optical Field Manipulation Science and Technology, Institute of Optics and Electronics, Chinese Academy of Sciences（中国科学院光电技术研究所光场操控科学与技术重点实验室）；Research Center on Vector Optical Fields, Institute of Optics and Electronics, Chinese Academy of Sciences（中国科学院光电技术研究所矢量光学场研究中心）；Tianfu Xinglong Lake Laboratory（天府兴隆湖实验室）；College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences（中国科学院大学材料科学与光电技术学院）
Programmable electro-optic frequency comb empowers integrated parallel convolution processing
State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University（中山大学电子与信息工程学院光电材料与技术国家重点实验室）；State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University（清华大学精密仪器系精密测量技术与仪器国家重点实验室）
Electrically-programmable frequency comb for compact quantum photonic circuits
Institute of Nuclear Sciences, Hacettepe University（哈杰泰普大学核科学研究所）；Department of Physics, Quaid-i-Azam University（奎德-阿扎姆大学物理系）；Department of Physics, Recep Tayyip Erdogan University（雷杰普·塔伊普·埃尔多安大学物理系）；Department of Nanoscience and Nanotechnology, Faculty of Arts and Science, Burdur Mehmet Akif Ersoy University（布尔杜尔·梅赫梅特·阿克夫·埃尔索伊大学文理学院纳米科学与纳米技术系）
Programmable Hard-X-Ray Spectral Comb Generation via Laser-Compton Scattering
University of California, Los Angeles（加州大学洛杉矶分校）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器设施）；California NanoSystems Institute（加州纳米系统研究所）
Transient High-Harmonic Generation from Solids: From Spectroscopy and Control to Programmable Emission
Advanced Research Center for Nanolithography（先进纳米光刻研究中心）；Imaging Physics, Faculty of Applied Sciences, Technische Universiteit Delft（代尔夫特理工大学应用科学学院成像物理）；Department of Physics and Astronomy, and LaserLaB, Vrije Universiteit（阿姆斯特丹自由大学物理与天文学系及激光实验室）
Photonic timing-engineered solitons for dual-microcomb metrology
Tsinghua University（清华大学）；International Quantum Academy, Shenzhen（深圳量子高等研究院）；Southern University of Science and Technology（南方科技大学）；University of Science and Technology of China（中国科学技术大学）
