Han Research Lab
Postdoc position available.
Van der Waals interactions are dipole-dipole interactions. A dipole is composed of two poles, which are separated by a distance. For example, an electric dipole is composed of a positive charge and a negative charge, which are separated by a distance r. Attractive van der Waals interactions can be used to create molecules. One type of molecule is called van der Waals molecules. We focus more on repulsive van der Waals interactions.
We are interested in studying the repulsive interactions between atoms and light-atom interactions.
One of our long-term goals is to study repulsive van der Waals interactions and to create few-body molecules using van der Waals interactions. For instance, van der Waals interactions can be used to create dimers, trimmers, and stable molecules, which are not achievable through common methods. In this case, van der Waals interactions are the dipole-dipole interactions between atoms. We use an atom, one electron and one ion core, as an electric dipole, whose size depends on the distance between the electron and ion core. To increase this electric dipole, we excite the atoms to Rydberg states, or highly excited states.
All these experiments are carried out at very low temperatures (T<<1 Kelvin or T≈0.3 mK). How to cool the atoms to such low temperatures? Similar to the two-car collision as shown in Fig. 1(a), the collision between one atom and one photon, or quantized light, can change the atom’s speed according to the momentum conservation as shown in Fig. 1(b). (The above image is from https://www.colourbox.com)
“Electric field excitation suppression in cold atoms.” Jianing Han, Juliet Mitchell, and Morgan Umstead, Atoms Vol. 8, 47 (2020); also available on arXiv:1904.09706.
“Six-body van der Waals interactions.” Jianing Han, Mol. Phys. e1584683 (2020).
“A magneto-optical trap created by 2nd-order external cavity diode lasers.” Jianing Han, Lindsay Hutcherson, Gayatri Deshmukh, Morgan Umstead, Andy Hu, Young Lee, Zhanguo Bai, and Juliet Mitchell, (arXiv:1812.00997) (2018).
“Repulsive potential peaks.” J. Han, J. Phys. B: At. Mol. Opt. Phys. 51, 215101 (2018)
“A ring cavity diode laser.” J. Han, Lindsay Hutcherson, Kaori Munekane, and Steven J. Shettlesworth, Journal of Modern Physics Vol. 11, 1236 (2020)
“Broadband Laser excitation of van der Waals polymers from a cold atomic gas.” J. Han, Mol. Phys. Vol. 115, 2479 (2017)
“Five-body interactions.” J. Han, Phys. Rev. A Vol. 95, 062502 (2017)
“Possible existence of van der Waals macrodimers.” J. Han, and Chunyan Hu, Mol. Phys. Vol. 114, 637 (2016)