LAMP-SEMINAR

TOWARDS BOSE–EINSTEIN CONDENSATION OF LASER-COOLED POLAR MOLECULES

Speaker: ARIJIT CHAKRABORTY (Senior Research Associate, Quantum Engineering and Technology Lab, Integrated Quantum Network Hub, University of Bristol)

Date and time
Venue
Online - Zoom

Abstract

Achieving quantum degeneracy of polar molecules requires overcoming fundamental challenges in molecule number, collisional stability, and phase-space density. In this work, I present the design and implementation of a third-generation experimental platform aimed at realizing quantum degenerate calcium monofluoride (CaF) molecules. The new system was engineered from the ground up to address key limitations of earlier apparatus. A redesigned cryogenic buffer gas source improves molecular flux and velocity distribution through optimized helium delivery and enhanced thermalization. A newly developed science chamber integrates cryogenic shielding to reduce blackbody radiation, PCB-based magnetic trapping coils compatible with low temperatures, and high-voltage electrodes enabling strong electric-field gradients for collisional shielding. In parallel, polarization modulation of the slowing laser beam was implemented to enhance Magneto Optical Trap loading efficiency, significantly increasing the number of trapped molecules. These technical advances collectively improve molecule number, lifetime, and control, providing a robust and scalable foundation for sympathetic and evaporative cooling toward quantum degeneracy. This third-generation platform establishes the necessary infrastructure for pursuing Bose–Einstein condensation of directly laser-cooled polar molecules and exploring strongly interacting dipolar quantum matter

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Short Biography
My research focuses on the experimental control of ultracold atoms and molecules for quantum technologies. During my PhD, I engineered radio-frequency dressed magnetic potentials to trap ultracold Rb atoms in novel geometries, such as ring-shaped traps, developing strong expertise in coherent manipulation and precision control of quantum gases. As a Research Associate in The Centre for Cold Matter at Imperial College London, I demonstrated state-dependent collisions between ultracold Rb atoms and laser-cooled CaF molecules, providing key benchmark collision rates toward sympathetic cooling of molecules. Building on this work, I was entrusted with designing, constructing, and commissioning a completely new third-generation molecular experiment from scratch, aimed at achieving Bose–Einstein condensation of CaF molecules. I led the development of the full cryogenic buffer gas source, vacuum and cryogenic systems, high-stability laser architecture, cryogenically shielded science chamber, optical dipole trap, and integrated control electronics; the platform is now fully operational and has successfully achieved trapping of CaF molecules in an optical dipole trap. I have recently joined the Quantum Engineering and Technology Lab, part of the Integrated Quantum Network Hub of the UK at the University of Bristol as a Senior Research Associate. I am currently developing cold-atom quantum memory systems compatible with telecom-wavelength photons for long-distance quantum networks, bridging fundamental many-body physics with scalable quantum communication technologies