# Han Ma

Perimeter Institute for Theoretical Physics

Areas of research:

### Research Interests

My research interest lies in the study of quantum phases and phase transitions.
1. I studied exotic phases, such as topological ordered states and fracton phase, have non-trivial entanglement structure resulting in interesting behaviours, such as ground state degeneracy and anyonic statistics of excitations.
2. I am also interested in continuous phase transitions, which can be described by conformal field theories. I am also interested in the pseudo-critical behavior whose universal properties are attributed to the complex fixed point.
3. I am now working on (non-)Fermi liquid which has extensive zero modes. This largely increases the complexity of the system. I use the so-called field theoretical renormalization group to study them.

### Positions Held

- Postdoctoral Researcher, Perimeter Institute for Theoretical Physics, 2019-present
- PhD student, Department of Physics, University of Colorado Boulder, 2014-2019

### Awards

- Block Award, Aspen Center for Physics, 2018

### Recent Publications

- Ma, H., & Lee, S. -S. (2024). Fermi liquids beyond the forward-scattering limit: The role of nonforward scattering for scale invariance and instabilities. Physical Review B, 109(4), 045143. doi:10.1103/physrevb.109.045143
- Ma, H., & Lee, S. -S. (n.d.). Exact effective action for the O(N) vector model in the large N limit. SciPost Physics, 15(3), 111. doi:10.21468/scipostphys.15.3.111
- Ma, H. (2023). Z2 Spin Liquids in the Higher Spin-S Kitaev Honeycomb Model: An Exact Deconfined Z2 Gauge Structure in a Nonintegrable Model. Physical Review Letters, 130(15), 156701. doi:10.1103/physrevlett.130.156701
- Ma, H. (n.d.). Quenched random mass disorder in the large N theory of vector bosons. SciPost Physics, 14(3), 039. doi:10.21468/scipostphys.14.3.039
- Haldar, A., Tavakol, O., Ma, H., & Scaffidi, T. (2023). Hidden Critical Points in the Two-Dimensional $O(n>2)$ model: Exact Numerical Study of a Complex Conformal Field Theory. doi:10.1103/PhysRevLett.131.131601
- Hsieh, T. -C., Ma, H., & Radzihovsky, L. (2022). Helical superfluid in a frustrated honeycomb Bose-Hubbard model. Physical Review A, 106(2), 023321. doi:10.1103/physreva.106.023321
- Ma, H., & Lee, S. -S. (n.d.). Constraints on beta functions in field theories. SciPost Physics, 12(2), 046. doi:10.21468/scipostphys.12.2.046

### Seminars

- Z2 spin liquids in the spin-S Kitaev honeycomb model, University of California, Santa Barbara, Kavli Institute for Theoretical Physics, Santa Barbara, California, 93106, United States, 2023/08/22
- Renormalization group for Metals, Michigan State University, East Lansing, United States, 2023/03/23
- Renormalization group for Metals, University of Illinois at Urbana-Champaign, Urbana, United States, 2023/02/20
- Renormalization group for Metals, University of Pittsburgh, Pittsburgh, United States, 2023/02/15
- Expanding the horizon of Renormalization group in quantum matter, University of Pittsburgh, Pittsburgh, United States, 2023/02/14
- Renormalization group for Metals, University of Toronto, Toronto, Canada, 2023/02/06
- Z2 spin liquids in spin-S Kitaev honeycomb model via parton construction, Quantum Matter Workshop, 2022/11/14, PIRSA:22110066
- Quenched random mass disorder in the large N vector boson model, Centre de recherches mathématiques, Montreal, Canada, 2022/08/29
- Nonperturbative RG flow and IR effective action of O(N) vector model, National Tsing Hua University, Hsinchu, Taiwan, 2022/03/01
- Nonperturbative RG flow and exact effective action of O(N) vector model, Cornell University, Ithaca, United States, 2021/08/12, Video URL