@article {ISI:000423393300009, title = {Probe Knots and Hopf Insulators with Ultracold Atoms}, journal = {CHINESE PHYSICS LETTERS}, volume = {35}, number = {1}, year = {2018}, month = {JAN}, pages = {013701}, publisher = {IOP PUBLISHING LTD}, type = {Article}, abstract = {Knots and links are fascinating and intricate topological objects. Their influence spans from DNA and molecular chemistry to vortices in superfluid helium, defects in liquid crystals and cosmic strings in the early universe. Here we find that knotted structures also exist in a peculiar class of three-dimensional topological insulators-the Hopf insulators. In particular, we demonstrate that the momentum-space spin textures of Hopf insulators are twisted in a nontrivial way, which implies the presence of various knot and link structures. We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates. The extracted Hopf invariants, knots, and links are validated to be robust to typical experimental imperfections. Our work establishes the existence of knotted structures in Hopf insulators, which may have potential applications in spintronics and quantum information processing.}, \%\%Address = {TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND}, issn = {0256-307X}, doi = {10.1088/0256-307X/35/1/013701}, author = {Deng, Dong-Ling and Wang, Sheng-Tao and Sun, Kai and Duan, L. -M.} } @article { ISI:000367356100002, title = {Hamiltonian tomography for quantum many-body systems with arbitrary couplings}, journal = {NEW JOURNAL OF PHYSICS}, volume = {17}, year = {2015}, month = {SEP 11}, issn = {1367-2630}, doi = {10.1088/1367-2630/17/9/093017}, author = {Wang, Sheng-Tao and Deng, Dong-Ling and Duan, L-M} }