@article {ISI:000468026100013,
title = {Emergent gauge field and the Lifshitz transition of spin-orbit coupled bosons in one dimension},
journal = {Sci Rep},
volume = {9},
year = {2019},
month = {MAY 16},
pages = {7471},
publisher = {NATURE PUBLISHING GROUP},
type = {Article},
abstract = {In the presence of strong spin-independent interactions and spin-orbit coupling, we show that the spinor Bose liquid confined to one spatial dimension undergoes an interaction-or density-tuned quantum phase transition similar to one theoretically proposed for itinerant magnetic solid-state systems. The order parameter describes broken Z2 inversion symmetry, with the ordered phase accompanied by non-vanishing momentum which is generated by fluctuations of an emergent dynamical gauge field at the phase transition. This quantum phase transition has dynamical critical exponent z similar or equal to 2, typical of a Lifshitz transition, but is described by a nontrivial interacting fixed point. From direct numerical simulation of the microscopic model, we extract previously unknown critical exponents for this fixed point. Our model describes a realistic situation of 1D ultracold atoms with Raman-induced spin-orbit coupling, establishing this system as a platform for studying exotic critical behavior of the Hertz-Millis type.},
issn = {2045-2322},
doi = {10.1038/s41598-019-43929-6},
author = {Cole, William S. and Lee, Junhyun and Mahmud, Khan W. and Alavirad, Yahya and Spielman, I. B. and Sau, Jay D.}
}
@article { ISI:000452326000001,
title = {Chiral anomaly without Landau levels: From the quantum to the classical regime},
journal = {PHYSICAL REVIEW B},
volume = {98},
number = {24},
year = {2018},
month = {DEC 6},
pages = {245109},
abstract = {We study the chiral anomaly in disordered Weyl semimetals, where the broken translational symmetry prevents the direct application of Nielsen and Ninomiya{\textquoteright}s mechanism and disorder is strong enough that quantum effects are important. In the weak disorder regime, there exist rare regions of the random potential where the disorder strength is locally strong, which gives rise to quasilocalized resonances and their effect on the chiral anomaly is unknown. We numerically show that these resonant states do not affect the chiral anomaly only in the case of a single Weyl node. At energies away from the Weyl point, or with strong disorder where one is deep in the diffusive regime, the chiral Landau level itself is not well defined and the semiclassical treatment is not justified. In this limit, we analytically use the supersymmetry method and find that the Chern-Simons term in the effective action which is not present in nontopological systems gives rise to a nonzero average level velocity which implies chiral charge pumping. We numerically establish that the nonzero average level velocity serves as an indicator of the chiral anomaly in the diffusive limit.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.98.245109},
author = {Lee, Junhyun and Pixley, J. H. and Sau, Jay D.}
}
@article { ISI:000452324400004,
title = {Chiral supercurrent through a quantum Hall weak link},
journal = {PHYSICAL REVIEW B},
volume = {98},
number = {21},
year = {2018},
month = {DEC 6},
pages = {214504},
abstract = {We use an effective model to calculate properties of the supercurrent carried by chiral edge states of a quantum Hall weak link. This {\textquoteleft}{\textquoteleft}chiral{{\textquoteright}{\textquoteright}} supercurrent is qualitatively distinct from the usual Josephson supercurrent in that it cannot be mediated by a single edge alone, i.e., both right- and left-going edges are needed. Moreover, the chiral supercurrent was previously shown to obey an unusual current-phase relation with period 2 phi(0) = h/e, which is twice the period of conventional Josephson junctions. We show that the {\textquoteleft}{\textquoteleft}chiral{{\textquoteright}{\textquoteright}} nature of this supercurrent is sharply defined, and is robust to interactions to infinite order in perturbation theory. We compare our results with recent experimental findings {[}Amet et al., Science 352 966 (2016)] and find that quantitative agreement in the magnitude of the supercurrent can be attained by making reasonable but critical assumptions about the superconductor quantum Hall interface.},
issn = {2469-9950},
doi = {10.1103/PhysRevB.98.214504},
author = {Alavirad, Yahya and Lee, Junhyun and Lin, Ze-Xun and Sau, Jay D.}
}