Group Seminar via zoom: Master thesis work presentation of Renhao Tao and Akira Kamijo

Renhao Tao and Akira Kamijo, MPQ
group meeting via Videoconference (Zoom)
Tuesday, March 31st 09:00 am (MEZ)

Dealing with the unique situation of partial lock downs worldwide and home office solutions at our Institute due to the current spreading of the Covid 19 virus, we are now holding our group seminars and journal clubs via video conference.
This procedure enables us to continue our research, enhance discussions and exchange important information.

Abstract Akira Kamijo:

A laser system for creating ground-state 23Na40K molecules

Ultra-cold polar molecules in their ground state offer unique possibilities to investigate quantum many-body systems due to their long-ranged dipole-dipole interaction. In our experiment, ultra-cold 23Na40K molecules are transferred to their electronic, vibrational and rotational ground-state via stimulated Raman adiabatic passage (STIRAP). This work focuses on the design and construction of a new STIRAP system following previous work at MIT [1] and Hefei [2]. An intermediate state in the B/c manifold is used, resulting in STIRAP transitions at 805 nm and 567 nm. To generate the 567 nm laser, the output of a 1134 nm external cavity diode laser is injection amplified by a gain chip to 250 mW and subsequently converted to 567 nm light by a periodically poled Lithium Niobate waveguide. 805 nm light is generated by a diode laser and amplified by a tapered amplifier. Using only solid-state lasers allows the system to be robust and easy to maintain. To ensure mutual coherence of these lasers, they are locked to a dual wavelength ultra-low expansion cavity allowing relative line widths of 1012 or lower.

[1] Park, J. W. et al. Phys. Rev. Lett. 114, 205302 (2015) [2] Liu, L. et al. Phys. Rev. Lett. 122, 253201 (2019)

Abstract Renhao Tao:

A wide-band EOM-based intensity-noise suppression system

Intensity fluctuation of laser for trapping atoms and molecules can cause heating and losses. Such intensity noise is especially prominent at 100 kHz for TiSa laser. We plan to implement a 10 MHz intensity stabilization system based on electric-optical modulator, to reduce intensity noise at round 100 kHz which is on the edge of the capbility of an acoustic-optical modulator. In this talk, I’ll review our current progress on having already achieved a noise rejection bandwidth of 1 MHz, and future plan to push it to 10 MHz.

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