Qubit regularized O(N) nonlinear sigma models

Motivated by the prospect of quantum simulation of quantum field theories, we formulate the O(N) nonlinear sigma model as a “qubit” model with an (N+1)-dimensional local Hilbert space at each lattice site. Using an efficient worm algorithm in the worldline formulation, we demonstrate that the model has a second-order critical point in 2+1 dimensions, where the continuum physics of the nontrivial O(N) Wilson-Fisher fixed point is reproduced. We compute the critical exponents nu and eta for the O(N) qubit models up to N=8, and find excellent agreement with known results in literature from various analytic and numerical techniques for the O(N) Wilson-Fisher universality class. Our models are suited for studying O(N) nonlinear sigma models on quantum computers up to N=8 in d=2,3 spatial dimensions.