Welcome to Chin Lab

 

Welcome to the ultracold atomic and molecular physics group in the Department of Physics and the James Franck Institute, at the University of Chicago. Here you will find a new and active research team exploring the quantum world at the lowest temperatures scientists can achieve, nearly a billionth of a degree Kelvin above absolute zero. Few sample images are shown in our Ultracold gallery. If you are interested in our research program or have any questions, please drop me a line, cchin @ uchicago.edu. I am looking forward to hearing from you!

Cheng Chin

Universal Scaling Symmetry

Ultracold atoms unveil a universal symmetry of systems crossing continuous phase transitions

For systems near continuous phase transitions, the details don’t matter. We can apply a universal theory to understand continuous phase transitions whether they occur in biological cell membranes, magnets, liquid crystals, or even in the entire early universe! Indeed, quantum phase transitions of our ultracold atomic gases should follow the same simple rules. But while the universal theory of static systems near continuous phase transitions is well established, the degree to which we can universally explain the dynamics of crossing such transitions presents an exciting new frontier. Ultracold atoms give us the power to explore this frontier by controlling many aspects of a phase transition, including how rapidly it is crossed, and carefully recording the resulting dynamics. In this way we can look for universal features of phase transition dynamics by observing whether we can really ignore the details! Read More

Li-Cs Mixture Experiment

Ultracold Bose-Fermi Mixture

In the realm of ultracold atoms, few species are less alike than Li-6 and Cs-133. The former is a light fermion and the latter is a heavy boson. In the LiCs lab, we study the unique physics that comes from the interaction of this unlikely pair. Owing to the existence of 5 interspecies Feshbach resonances at high magnetic field (800 - 950 G), we are able to chose between a wide variety of combinations of intraspecies scattering length while retaining continuous tuning of the interspecies scattering length. This tunability affords a spectacular level of control over the system and allows access to a wide variety of physics.Read More

Quantum Matter Synthesizer

Quantum Matter Synthesizer

The Quantum Matter Synthesizer (QMS) is a new experimental platform for quantum simulations and engineering new quantum phases. Once completed, the QMS will be able to load atoms into a far-detuned lattice projected through a high numerical aperture objective lens, image the atomic distribution and cool the atoms to the vibrational ground state, and then dynamically turn off and rearrange lattice sites to achieve the desired filling fraction and spin order. We will achieve this dynamically re-arrangeable lattice by forming our 2D optical potential with Digital Micromirror Devices (DMD).Read More

Particle Levitation

Levitation of Macroscopic Particles by Thermophoretic Force

We demonstrate levitation of micron-sized ice, ceramic, glass and polyethylene particles at low pressure (1-10 Torr) in the presence of a temperature gradient. Under thermophoresis, collisions with more energetic gas molecules from below provide a net upward momentum transfer. Particles initially levitate a few millimeters above a cold plate due to the Knudsen Compressor effect. Particles are then accelerated upwards by the thermophoretic force in the direction from hot to cold in the rarefied gas. In the appropriate pressure regime this allows for stable levitation for up to two hours. Lately we have also succeeded in levitating other materials, including thistle seeds and lint. Our future goals are to levitate water droplets, push levitated particles with a laser, and examine the dynamics behind multi-particle levitation.Read More

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