Development of a pulsed laser with rapid frequency shift in ultraviolet region for realizing laser cooling of positronium

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K13862
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
• Research Institution: The University of Tokyo
• Principal Investigator: Shu Kenji 東京大学, 大学院工学系研究科(工学部), 助教 (70881233)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: 反粒子 / ポジトロニウム / レーザー冷却 / レーザー / 光周波数変調 / 量子電磁力学 / 対称性

Outline of Final Research Achievements

To testify quantum electrodynamics and solve the mystery that antimatter has disappeared from our universe, I developed a laser system for cooling positronium (Ps), which is the bound state of an electron and a positron - the antiparticle of electron. The laser was required to be well controlled in both time and spectral domains due to difficulties arising from that Ps has the light mass, which is approximately one thousandth of that of hydrogen atom, and short lifetime of approximately 100ns. The unprecedented control was achieved by enhancing a method to modulate an optical spectrum.

Free Research Field

量子エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究の成果により、Psを1K以下の極低温へ冷却することが可能となり、Psの高い温度が大きな不確かさを生んでいた分光測定の高精度化や、原子コヒーレンスが向上することでPs干渉計の実現への応用が拓ける。これにより、暗黒物質の存在をはじめとする現代物理学の問題の解決や、反粒子にまつわる謎の解明が期待される。両者とも、新現象の発見の傾向が見られるなど、国内外の機関において熱心に研究がなされており、本研究は高い注目を集めると考えられる。