title: Emergent Weyl excitations in systems of polar particles.
abstract: Weyl fermions are massless chiral particles first predicted in 1929 and once thought to describe neutrinos. Although never observed as elementary particles, quasiparticles with Weyl dispersion have recently been experimentally discovered in solid-state systems causing a furore in the research community. Systems with Weyl excitations can display a plethora of fascinating phenomena and offer great potential for improved quantum technologies. Here, we show that Weyl excitations generically exist in three-dimensional systems of dipolar particles with weakly broken time-reversal symmetry (by for example a magnetic field). They emerge as a result of dipolar-interaction-induced transfer of angular momentum between the J=0 and J=1 internal particle levels. We also discuss momentum-resolved Ramsey spectroscopy methods for observing Weyl quasiparticles in cold alkaline-earth-atom systems. Our results provide a pathway for a feasible experimental realization of Weyl quasiparticles and related phenomena in clean and controllable atomic systems.
authors.affiliation: Physics Department, University of Colorado, Boulder, Colorado 80309, USA.|JILA, NIST, University of Colorado, Boulder, Colorado 80309, USA.|Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA.|Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Syzranov
authors.affiliation: JILA, NIST, University of Colorado, Boulder, Colorado 80309, USA.|Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Wall
authors.affiliation: Physics Department, University of Colorado, Boulder, Colorado 80309, USA.|JILA, NIST, University of Colorado, Boulder, Colorado 80309, USA.|Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Bihui
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Physics Department, University of Colorado, Boulder, Colorado 80309, USA.|JILA, NIST, University of Colorado, Boulder, Colorado 80309, USA.|Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Gurarie
authors.affiliation: Physics Department, University of Colorado, Boulder, Colorado 80309, USA.|JILA, NIST, University of Colorado, Boulder, Colorado 80309, USA.|Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Rey