# Level Spectroscopy in Quantum Antiferromagnets Using Monte Carlo Simulations

### Abstract

The low-energy spectrum of antiferromagnets reveal valuable information

about the nature of the phase or phase transition in such systems. I review

the recent works done in collaboration with Suwa and Sandvik

[Phys. Rev. B 92, 195145 (2015), Phys. Rev. B 94, 144416 (2016)]

on how to probe the dispersion of the excitations in a

variety of SU(2) symmetric S=1/2 spin systems using

quantum Monte-Carlo methods.

Various applications are discussed in both one and two

dimensions, which include probing the critical excitations for

conventional and unconventional quantum critical points. In

the latter case, the excitation spectrum is highly unusual and has

additional gapless modes and possible emergent symmetries

which are not present otherwise.

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Copyright (c) 2018 Arnab Sen

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