Many-body interactions

From 3D to 2D and Back Again

Cory Dean
Monday, September 18, 2017 - 4:30pm to 5:30pm

Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, is probably the best known, and most extensively characterized two-dimensional material.  However, this represents just one of a larger class of van der Waals materials, in which atomic monolayers can be mechanically isolated from the bulk.  By integrating these materials with one another,  an exciting new opportunity has emerged in which layered heterostuctures can be fabricated with properties beyond those of the constituent materials. In this talk I will present some of our recent efforts where...

Multidisciplinary Research Program of the University Research Initiative (MURI)

  • By Aude Marjolin
  • 9 May 2016

The MURI program supports basic research in science and engineering at U.S. institutions of higher education that is of potential interest to DoD.

The program is focused on multidisciplinary research efforts where more than one traditional discipline interacts to provide rapid advances in scientific areas of interest to the DoD. By supporting multidisciplinary teams, the program is complementary to other DoD basic research programs that support university research through single-investigator awards.

Department of Physics and Astronomy, University of Pittsburgh
Ph.D., Physics, University of Illinois at Urbana-Champaign, 2007

My research focuses on describing and controlling dynamics of quantum many-body systems. My goal is to address some of the fundamental problems of ultracold atom and condensed matter physics:
  1. What are the generic alternatives to thermalization?
  2. Interplay of pseudo gauge-fields, topology and dynamics
  3. Dynamics of mesoscopic systems and (with and without non-Abelian excitations)

Addressing these fundamental physics questions will have important implications for: (1) understanding the limitations and alternatives to thermodynamics, (2) generating non-Abelian excitations in static ultracold atom systems and building photonic crystals with broken time-reversal symmetry, (3) control over non-Abelian excitations will be useful for building quantum memory and quantum computers.

Most Cited Publications
  1. "Majorana fermions in equilibrium and in driven cold-atom quantum wires." Liang Jiang, Takuya Kitagawa, Jason Alicea, AR Akhmerov, David Pekker, Gil Refael, J Ignacio Cirac, Eugene Demler, Mikhail D Lukin, Peter Zoller. Physical review letters.
  2. "The ‘Higgs’ amplitude mode at the two-dimensional superfluid/Mott insulator transition." Manuel Endres, Takeshi Fukuhara, David Pekker, Marc Cheneau, Peter Schauβ, Christian Gross, Eugene Demler, Stefan Kuhr, Immanuel Bloch. Nature.
  3. "Observation of elastic doublon decay in the Fermi-Hubbard model." Niels Strohmaier, Daniel Greif, Robert Jördens, Leticia Tarruell, Henning Moritz, Tilman Esslinger, Rajdeep Sensarma, David Pekker, Ehud Altman, Eugene Demler. Physical review letters.
  4. "Hilbert-glass transition: New universality of temperature-tuned many-body dynamical quantum criticality." David Pekker, Gil Refael, Ehud Altman, Eugene Demler, Vadim Oganesyan. Physical review x.
  5. "Amplitude/Higgs modes in condensed matter physics." David Pekker, CM Varma. Annu. Rev. Condens. Matter Phys..
Recent Publications
  1. "Emergent mode and bound states in single-component one-dimensional lattice fermionic systems." Yuchi He, Binbin Tian, David Pekker, Roger SK Mong. Physical Review B.
  2. "Parahydrophobicity and stick-slip wetting dynamics of vertically aligned carbon nanotube forests." Ziyu Zhou, Tongchuan Gao, Sean McCarthy, Andrew Kozbial, Susheng Tan, David Pekker, Lei Li, Paul W Leu. Carbon.
  3. "Reservoir engineering of Cooper-pair-assisted transport with cold atoms." François Damanet, Eduardo Mascarenhas, David Pekker, Andrew Daley. New Journal of Physics.
  4. "Bulk Geometry of the Many Body Localized Phase from Wilson-Wegner Flow." Xiongjie Yu, David Pekker, Bryan K Clark. arXiv preprint arXiv:1909.11097.
  5. "Pascal conductance series in ballistic one-dimensional LaAlO/SrTiO channels." Megan Briggeman, Michelle Tomczyk, Binbin Tian, Hyungwoo Lee, Jung-Woo Lee, Yuchi He, Anthony Tylan-Tyler, Mengchen Huang, Chang-Beom Eom, David Pekker, Roger SK Mong, Patrick Irvin, Jeremy Levy. arXiv preprint arXiv:1909.05698.
Department of Physics and Astronomy, University of Pittsburgh
Ph.D., University of Texas at Austin, 1999

Dr. Liu is interested in the theory of novel emergent phenomena of quantum condensed matter. He has considerable experience in interacting Bose and Fermi gases of cold atoms, quasi–one–dimensional electronic, charge and/or spin liquids (such as coupled Luttinger liquid models), and quasi 2D strongly correlated electronic systems such as high temperature superconductors. He also has a background in quantum field theory and is interested in all applications of it to condensed matter. His current research focuses on the rapidly developing field of ultra–cold atomic gases, driven largely by many ongoing experiments worldwide.

Selected Publications: 
Most Cited Publications
  1. "Interior gap superfluidity" WV Liu, F Wilczek - Physical review letters, 2003 - APS
  2. "Stability criteria for breached-pair superfluidity" MMN Forbes, E Gubankova, WV Liu, F Wilczek - Physical review letters, 2005 - APS
  3. "Atomic matter of nonzero-momentum Bose-Einstein condensation and orbital current order" WV Liu, C Wu - Physical Review A, 2006 - APS
  4. "Breached pairing superfluidity: Possible realization in QCD" E Gubankova, WV Liu, F Wilczek - Physical review letters, 2003 - APS
  5. "Topological semimetal in a fermionic optical lattice" K Sun, WV Liu, A Hemmerich, SD Sarma - Nature Physics, 2012 -
Recent Publications
  1. "Clean Floquet Time Crystals: Models and Realizations in Cold Atoms."     Huang, B., Wu, Y.-H., Liu, W.V. Physical Review Letters 120(11), 110603 (2018).
  2. "Odd-parity topological superfluidity for fermions in a bond-centered square optical lattice." optical lattice    Xu, Z.-F., Hemmerich, A., Liu, W.V. Physical Review A 96(5), 053607 (2017).
  3. "Frustrated Magnetism of Dipolar Molecules on a Square Optical Lattice: Prediction of a Quantum Paramagnetic Ground State." Zou, H., Zhao, E., Liu, W.V. Physical Review Letters 119(5) 050401 (2017).
  4. "Effective theory of interating fermions in shaken square optical lattices." Keleş, A., Zhao, E., Liu, W.V. Physical Review A 95(6) 063619 (2017).
  5. "Physics of higher orbital bands in optical lattices: A review." Li, X., Liu, W.V. Reports on Progress in Physics 79(11) 116401 (2016).

Vincent Liu Awarded Grant to Investigate Condensed Matter and Atomic-Optical Physics

  • By Aude Marjolin
  • 15 December 2015

PQI faculty Wensheng Vincent Liu has received a five-year $1.42 million grant from the Air Force Office of Scientific Research to predict and understand topological phases of quantum atomic matter (i.e., a cold ensemble of interacting atoms) under novel conditions, well beyond the standard regimes. 

While the research is theoretical in nature, the findings are expected to motivate and guide ongoing and future experiments in atomic, molecular, and optical physics, as well as provide the models for engineering novel electronic materials of the desired quantum properties in condensed matter physics. The acquired new knowledge has the potential to find applications in the future generation of precision quantum-based devices and possibly topological quantum computers and communication technology.