Other research topics
I am generally interested in quantum many-body phenomena, including quantum material and synthetic many-body systems such as optical lattices. My recent interest is understanding the unusual slow dynamics in 1D bosons with double well dispersion related to fractons through effective dipole conservation.
Constrained Motions and Slow Dynamics in One-Dimensional Bosons with Double-Well Dispersion
We demonstrate slow dynamics in the symmetry-broken phase of 1D bosons with double-well dispersion and identify the relation to fractons through dipole conservation of domain walls. The superfluid stiffness vanishes at T=0 despite being a Bose condensate. In addition, we study the hydrodynamics originating from the interacting quantum critical point (slightly deformed from the Lifshitz fixed point) and confirm slow dynamics and thermal activated superfluid stiffness.
Correlated insulator in two Coulomb-coupled quantum wires
Motivated by the recently discovered incompressible insulating phase in the bilayer graphene exciton experiment [Zeng et al., arXiv:2306.16995], we study using bosonization two Coulomb-coupled spinless quantum wires and examine the possibility of realizing the similar phenomenology in one dimension. We explore the possible phases as functions of kF 's and interactions. We show that an incompressible insulating phase can arise for two lightly doped electron-hole quantum wires due to strong interwire interactions. Such an insulating phase forms a parity-even wire-antisymmetric charge density wave without interwire phase coherence, which melts to a phase, allowing for a perfect negative drag upon heating. The finite-temperature response is qualitatively consistent with the “exciton solid” phenomenology in the bilayer graphene exciton experiment.
Mott glass in one dimension
The role of disorder is often regarded as secondary in the strongly correlated electronic systems. Can the interplay of disorder and strong interaction induces unconventional phases? To answer this question, we study linearly interacting fermions with quench disorder in 1D. The ground state demonstrates a Mott glass - zero compressibility and nonzero optical conductivity. This phase in 1D was first speculated by Orignac, Giamarchi, and Le Doussal. However, the original proposal was subsequently questioned by Thomas Nattermann, Petković, Ristivojevic, and Schütze. Our model with linearly interacting potentials evades the compelling arguments against the Mott glass phase. The Mott glass is best viewed as confined electrons + localized dipole modes.
Integrable models: Correlation and dynamics
During my first two years of PhD (with Adilet Imambekov), I focused on the correlation functions and integrable dynamics Lieb-Liniger model. We derived a general formula for the local three-body correlation functions that can be generalized to finite-temperature and non-thermal distributions. Later, we adopt the concept of generalized Gibbs ensemble and give predictions of post-quenched steady state of interacting bose gas in 1D. The paper on integrable dynamics is a milestone paper in the field as it was the first attempt for studying interaction quench using Bethe ansatz.
Frustrated spin systems
I studied spin ice models which contain a two-in-two-out constraint for each tetrahedron. Such a constraint can be viewed as a Gauss law for the spin fields. Divergenceless condition indicates the absence of magnetic monopole. Violation of local two-in-two-out is corresponding to create monopoles from the spin ice vacuum. The emergent Gauss law condition of a spin ice manifests the pinch point in its spin structure factor. I investigated a semiclassical spin ice model that includes perturbations due to quantum fluctuations. Such a semiclassical model demonstrates a first order phase transition. I also computed spin correlation function of diluted dipolar spin ice model which corresponds to neutron scattering patterns in Ho2−xYxTi2O7. More recently, I help to investigate the spin correlation functions in the fractonic spin liquid systems which exhibits four-fold symmetry in the pinch points.
Phys. Rev. B 98, 165140 (2018)
