Description
Positronium (Ps), a bound state of an electron and a positron, is a purely leptonic and anti-particle system. Preparing a cold gas of Ps leads to precision spectroscopy and a realization of Bose-Einstein condensation of exotic atoms. Owing to the nature of the particle-antiparticle pair, Ps has a finite lifetime of 142 ns. Therefore, developing a rapid cooling method is the key to cool Ps effectively.
Laser cooling using the 1S-2P transition is one of the most promising methods for Ps cooling. With laser cooling, Ps atoms at room temperature could ideally be cooled to the photon recoil limit of 0.6 K within one microsecond. The temperature is well below 150 K, achieved by a conventional cooling method via momentum exchange processes with a cold Ps converter[1].
It is well known that laser cooling using continuous-wave lasers can reduce the temperature of a gas of atoms to submillikelvin temperatures[2]. However, because of the finite lifetime and the small mass of Ps, a cooling laser for Ps should be a unique pulsed laser that has a broadband spectrum, a frequency chirp, and a long pulse duration of several hundred nanoseconds[3]. We designed and developed a prototypical cooling laser (Figure 1) that satisfies these requirements. We also numerically simulated its oscillation dynamics and successfully reproduced the measured temporal and spectral structures of the laser[4].
[1] S. Mariazzi, P. Bettotti, and R. S. Brusa, Physical Review Letters 104, 243401 (2010).
[2] W. D. Phillips, Reviews of Mordern Physics 70, 721 (1998).
[3] K. Shu, X. Fan, T. Yamazaki, T. Namba, S. Asai, K. Yoshioka, and M. Kuwata-Gonokami, Journal of Physics B: Atomic, Molecular and Optical Physics 49, 104001 (2016).
[4] K. Yamada, Y. Tajima, T. Murayoshi, X. Fan, A. Ishida, T. Namba, S. Asai, M. Kuwata- Gonokami, E. Chae, K. Shu, and K. Yoshioka, Physical Review Applied 16, 014009 (2021).
| Presenter name | Tajima Yohei |
|---|---|
| How will you attend ICAP-27? | I am planning on in-person attendance |
