Strategies for Quantum-Accelerated Interpolator Construction in Classical Simulations of Lattice Field Theories

Optimized interpolating operators have the potential to accelerate the computation of hadron and nuclear matrix elements in lattice QCD. With decreased overlap onto low-lying excited states, optimized interpolated states require less euclidean time evolution to suppress unwanted contributions. This makes for a more efficient preparation of initial and final states in matrix elements, reducing computational costs.

However, classical interpolator optimization itself may be computationally expensive. In this proof-of-principle work, we show that optimal interpolator constructions can be determined in a small-scale quantum simulation. We use a small-scale quantum Hamiltonian simulation of the Schwinger model to variationally optimize an interpolator construction for a pseudoscalar meson state in the theory, and then employ that construction in a classical path-integral Monte-Carlo calculation, where systematically improvable continuum-limit scaling is possible.