Scientific Calendar Event


Nils Niggemann
(Freie Universität Berlin)

Spin models with emergent gauge theories are known to realize states of matter where single spin degrees of freedom fractionalize into intriguing quasiparticles with unique properties. An illustrious example is quantum spin ice where quantum fluctuations between an extensively degenerate manifold of classical ground state configurations realize a version of quantum electrodynamics where emergent electric and magnetic fields allow for excitations of electric charges, magnetic monopoles and photons. Generalizations of such gauge theories, where the electric field is not described by a (rank 1) vector but by a higher rank tensor field, are known to host even more exotic quasiparticles known as fractons, which are completely immobile unless paired together. While classical models with such excitations can be constructed, investigations of the effects of quantum fluctuations have rarely been attempted, mainly due to the complicated nature of these models. In this talk, I will present a simple and minimal construction for such a fracton-spin liquid on a square lattice model and use numerically exact methods to study its quantum ground state, where strong evidence for a quantum fracton-spin liquid can be found.
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