=== 量⼦科学研究センターセミナーのご案内 ===6/21（⾦）に⽶国コロラド⼤学ボルダー校より、Scott Diddams 教授の研究グループの Connor Fredrick 博⼠と Pooja Seckhar さんの２名をお招きし、量⼦科学研究センターセミナーを開催致しますので、ご案内致します。
Scott Diddams 教授は、光周波数コム、精密計測、量⼦光学の研究において世界を牽引する研究者で、本学の特別栄誉教授 John Hall 先⽣が 2005 年にノーベル物理学賞を受賞された研究においても多⼤な貢献をされています。
今回、同グループのメンバーである Connor Fredrick 博⼠と Pooja Seckhar さんが、横浜で開催される天⽂学の国際会議に参加される機会に本学を訪問されます。
本セミナーでは最新の研究成果をご紹介いただきますので、研究室の研究員、学⽣の皆様もお誘いあわせのうえ、どうぞ奮ってご参加ください。
[講演情報]
⽇時：2024 年 6 ⽉ 21 ⽇(⾦) 16:30 - 17:30場所：東 6 号館 337 室
主催：量⼦科学研究センター[1]
Title: Precision near-infrared solar spectroscopy with a frequency comb calibrated laser heterodyne radiometer
Speaker: Dr. Connor Fredrick, the University of Colorado Boulder
Abstract: For many important optical and infrared systems of interest, such as those in astronomy and atmosphericremote sensing, spectroscopic information is carried by light that is thermal in origin. With incoherent light, it is notpossible to use the phase-sensitive or frequency counting techniques of optical frequency metrology, and one isrestricted to measuring the amount of radiation instead of its frequency. Laser heterodyne radiometry is a compelling
option for making spectral measurements of thermal light at known frequencies. We report on the design anddevelopment of a frequency-comb-calibrated near-infrared heterodyne spectrometer. We use this comb-calibrated
approach to measure a solar iron line using two instrument configurations: one that measures the line shape of thetarget transition at high resolution (R~106), and another that uses lock-in detection to stabilize a laser to the target
transition, directly tracking its frequency against the comb. In both configurations, the measurements reach sub-50
cm/s Doppler velocity precision within a single day.

Bio:Connor Fredrick is a postdoctoral associate at the University of Colorado Boulder and works in Scott Diddams' groupat NIST. His research spans laser spectroscopy, nonlinear optics, and optical frequency combs with an emphasis on
precision astronomical applications. Of note are his contributions to the development and long-term operation of the30 GHz comb system used with the near-infrared Habitable-Zone Planet Finder spectrograph. More recently, Connorhas focused on exploring the limits of comb-calibrated heterodyne radiometry for high-resolution solar spectroscopy.

[2]Title: Tunable laser frequency combs for astronomical spectrograph characterization and calibration
Speaker: Pooja Sekhar, the University of Colorado Boulder
Abstract: The discovery and characterization of earth-like exoplanets by radial velocity technique is an extremely
challenging spectroscopy problem. Currently, detector defects, stellar activity and the absence of a reliable laser
frequency comb (LFC) around the peak of the solar spectrum are major impediments to reaching the required 10-10level of RV precision. To address these challenges, tunable LFCs that can map the point spread function across aspectrograph’s entire bandwidth are required. This talk demonstrates a scannable 30 GHz electro-optic (EO) combspanning 700 – 1300 nm by tuning a combination of laser center frequency and mode spacing. This talk also delves
into the development of LFCs in 350 – 500 nm band using periodically-poled lithium niobate waveguides leveraging
both χ(2) and χ(3) nonlinearities.
Bio:Pooja Sekhar is a PhD student in Physics at University of Colorado Boulder. She received her BSMS
degrees in Physics from IISER Thiruvananthapuram (India). She joined Scott Diddams’ research group in 2020 andis currently working on the development of laser frequency combs to calibrate astronomical spectrographs aimed at
finding exoplanets.

お問合せ：量⼦科学研究センター/基盤理⼯学専攻美濃島 薫 k.minoshima@uec.ac.jp