Tongcang Li

NOTE: E-mail addresses end with

Tongcang Li
PHYS 91 Lab
(765) 496-0072
(765) 494-3020

Assistant Professor of Electrical and Computer Engineering

Lab Homepage:


  • 2011: Ph.D. in Physics, The University of Texas at Austin, USA.
    Dissertation: Fundamental Tests of Physics with Optically Trapped Microspheres
  • 2004: B.S. in Physics, University of Science and Technology of China
    Thesis: Effects of Dangling Ends on the Conductance of Side-contacted Carbon Nanotubes


  • 08/2014 - : Assistant Professor of Physics and Astronomy, Purdue University
  • 08/2014 - : Assistant Professor of Electrical and Computer Engineering, Purdue University
  • 08/2011 - 07/2014: Postdoctoral Scholar, University of California, Berkeley, CA, USA
  • 06/2011 – 07/2011: Postdoctoral Fellow, The University of Texas at Austin.
  • 01/2005 – 05/2011: Graduate Research Assistant, The University of Texas at Austin.
  • 09/2004 – 12/2004: Teaching Assistant in Physics, The University of Texas at Austin.

Other Experiences

  • Reviewers for Nature Communications, Physical Review Letters, Nano Letters, Laser & Photonics Reviews, New Journal of Physics, Optics Express, Nanotechnology, etc.

Awards and Honors

  • NSF CAREER Award, 2016
  • My paper "Science, 328, 1673 (2010)" on Brownian motion was included in the “Science in the Classroom”, an NSF-funded AAAS project for teaching high school and college students, 2013
  • Springer Theses Prize, Springer Science + Business Media, 2012
  • Outstanding Dissertation in Physics, Department of Physics, The University of Texas at Austin, 2011
  • Chinese Government Award for Outstanding Self-financed Students Abroad, China Scholarship Council, 2011
  • Jean Bennett Memorial Student Travel Grant, Optical Society of America Foundation, 2010
    (Only one student is awarded this grant per year. Citation: “In recognition of outstanding research excellence”.)
  • Lawrence C. Biedenharn Endowment for Excellence, University of Texas at Austin, 2010
  • Excellent Bachelor Thesis, University of Science and Technology of China, 2004.
  • Superexcellent Research Program of Undergraduate Students, University of Science and Technology of China, 2003.
  • Academic Excellence Awards: 2000-2003

Key Accomplishments

I have published one book and 20 papers in Science, Nature Physics, Physical Review Letters (including two cover stories) and other leading journals. My work has been selected as a Research Highlight by Nature and Nature Photonics on four occasions and has been widely reported by major media and professional magazines, including NBC News, Fox News, Scientific American, New Scientist, Physics Today, Physics World, Materials Today, etc. Here are my key research accomplishments:
  • Optomechanics of Levitated Dielectric Particles: I proposed and led a pioneering experiment to trap and cool glass microspheres in vacuum towards the quantum ground state of an optical tweezer. We have trapped glass microspheres in high vacuum (~10-6 torr), and cooled their center-of-mass motion from room temperature to about 1.5 mK.
  • Brownian motion at short time scales: I proposed and led an experiment that measured the instantaneous velocity of a Brownian particle for the first time, a task that was said to be impossible by Albert Einstein in 1907. We have built an optical tweezer with a spatial resolution of about 2 fm / Hz^0.5.
  • Space-time crystals of trapped ions and Bose-Einstein condensates: I proposed and initiated the ongoing experiment to create space-time crystals of trapped ions by confining ions in a ring trap with a static magnetic field. I have also experimentally studied the quantum transport of ultracold atoms in an optical lattice and the dynamics of a Bose-Einstein condensate driven by a kicked rotor.
  • Novel optical microscopy and beam shaping: I invented axial plane optical microscopy that can directly image a sample’s cross-section parallel to the optical axis of an objective lens without scanning, enabling fast, high-contrast, and convenient 3D imaging of large biological tissues. We have also demonstrated novel laser beams that can propagate along elliptical or parabolic trajectories in water.
  • Charge and spin transport in nanostructures: I proposed a model to theoretically investigate the electrical spin injection from a ferromagnet/tunnel barrier contact into a semiconductor. I have also investigated the quantum conductance of graphene nanoribbons with edge defects, and found that a weak disorder would change zigzag nanoribbons from metallic to semiconducting.


  • Tongcang Li, Fundamental Tests of Physics with Optically Trapped Microspheres (Springer Theses) (Springer, New York, 2013)

Selected Journal Publications

  • Tongcang Li, S. Kheifets, D. Medellin, and M. G. Raizen, “Measurement of the instantaneous velocity of a Brownian particle”, Science, 328, 1673 (2010)
  • Tongcang Li, Simon Kheifets, Mark G. Raizen, “Millikelvin cooling of an optically trapped microsphere in vacuum”, Nature Physics, 7, 527 (2011)
  • Tongcang Li, Z.-X. Gong, Z.-Q. Yin, H. T. Quan, X. Yin, P. Zhang, L.-M. Duan, X. Zhang, “Space-time crystals of trapped ions”, Phys. Rev. Lett., 109, 163001 (2012) (cover story)
  • Peng Zhang, Yi Hu, Tongcang Li, Drake Cannan, Xiaobo Yin, Roberto Morandotti, Zhigang Chen, Xiang Zhang. Nonparaxial Mathieu and Weber accelerating beams. Phys. Rev. Lett. 109, 193901 (2012) (cover story)
  • S. Kheifets, A. Simha, K. Melin, Tongcang Li, M. G. Raizen. "Observation of Brownian motion in liquids at short times: instantaneous velocity and memory loss", Science, 343, 1493 (2014)
  • Peng Zhang*, Tongcang Li*, Jie Zhu*, Xuefeng Zhu, Sui Yang, Yuan Wang, Xiaobo Yin, and Xiang Zhang. "Generation of acoustic self-bending and bottle beams by phase engineering", Nature Communications5, 4316 (2014) (* coleading authors)
Last Updated: May 17, 2016 4:46 PM