Harvard Condensed Matter Theory Seminars

Sung-Sik Lee, MIT

Fractionalization in a strongly correlated exciton system
Strongly correlated exciton system can exhibit fractionalized phases besides conventional disordered and bose condensed phases. In the fractionalized phase, charge neutral `half exciton' arises as a low energy degree of freedom along with an emergent U(1) gauge field. Starting from a matrix model model which describes non-relativistic exciton bose condensates in a degenerate band, I will show how a relativistic gauge theory emerges at low energies with either fractionalized boson or fermion depending on the coupling constants. From a world line picture of exciton it will be shown that the deconfinement phase can occur in the gauge theory despite an infinite bare gauge coupling. A possibility of coexistence between fractionalization and conventional long range order of exciton will also be discussed based on a vortex approach which is `electro-magnetically' dual to the world line approach. The exciton model can be numerically simulated without sign problem and some of our results will be shown.

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