Quantum Computation of Phase Transition in Interacting Scalar Quantum Field Theory

It has been demonstrated that the critical point of the phase transition in scalar quantum field theory with a quartic interaction in one space dimension can be approximated via a Gaussian Effective Potential (GEP). We discuss how this critical point can be estimated using quantum hardware. We perform quantum computations with various lattice sizes and obtain evidence of a transition from a symmetric to a symmetry-broken phase. We use both discrete- and continuous-variable quantum computation. We implement the ten-site case on IBM quantum hardware using the Variational Quantum Eigensolver (VQE) algorithm to minimize the GEP and identify lattice level-crossings. These are extrapolated via simulations to find the continuum critical point.