Exploration of macroscopic superposition states with single nanoparticles levitated in vacuum

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H01822
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Aikawa Kiyotaka 東京工業大学, 理学院, 准教授 (10759450)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: ナノ粒子 / 浮揚オプトメカニクス / フィードバック冷却

Outline of Final Research Achievements

We constructed a new apparatus consisting of an optical system and a vacuum chamber. With this apparatus, we demonstrated electric feedback cooling of single charged nanoparticles in an optical lattice to near the ground state. In this experiment, we observed that the motion of nanoparticles in an optical lattice was heated by the laser phase noise and showed that the heating effect was made negligible by the reduction of the laser phase noise. Furthermore, we investigated the possibility of measuring the momentum of nanoparticles via the time-of-flight method and found that the momentum measurements of charged nanoparticles were difficult due to the strong impact of the residual electric fields in the vacuum chamber. To solve this issue, we developed a method for neutralizing nanoparticles and cooling them to near the ground state.

Free Research Field

量子光学・ナノ物理

Academic Significance and Societal Importance of the Research Achievements

本研究により、真空中の単一ナノ粒子を量子基底状態付近まで冷却する技術が開発できた。特に、ナノ粒子を中性化した上で基底状態付近へと冷却できることは、多くの応用の観点から重要である。まず、残留電場の影響なく飛行時間法による運動量測定が行えるため、ナノ粒子の重心運動に関する量子性を探る研究が可能となる。また、残留電場の影響を受けずに、ナノ粒子を加速度センサとして利用することが可能となる。これらの意義に加え、本研究の本来の目的からは外れるものの、従来知られていたものと比べて高い周波数帯域で極めて低い強度ノイズのレーザーを開発できた点も、レーザーを用いる種々の応用において有用と期待される。