Mass gap calculation in an asymptotically free theory on a quantum computer

The nucleus at the heart of the atom carries most of its mass. This mass is understood to be generated dynamically from the interactions between the quarks and gluons. Mass generation is known to be related to confinement and asymptotic freedom in Quantum Chromodynamics (QCD). However, further theoretical and experimental efforts are still required to obtain a more comprehensive and quantitative understanding. Quantum computations involving bosons, such as the gluons, are a challenge since an arbitrarily large number of bosons can occupy a single site. There has been recent progress in formulating the nonlinear O(3) sigma model on a 2-dimensional space-time lattice. The sigma model is an asymptotically free theory of bosons and shares many of the mechanisms for mass generation with QCD. We present results for the mass gap in the sigma model. We develop an algorithm to calculate the mass gap from the time dependence of the expectation value of an operator that initiates a transition between the ground and excited states. We present results at several lattice box sizes on a quantum computer.