In this work I apply a recently proposed improvement procedure, originally conceived to reduce finite lattice-spacing effects in transfer matrices for dilute Fermi systems, to tuning operators for the calculation of observables. I construct, in particular, highly improved representations for the energy and the contact as a first step in an improvement program for finite-temperature calculations. I illustrate the effects of improvement on those quantities with a ground-state lattice calculation at unitarity.

• Received 25 March 2012

DOI:https://doi.org/10.1103/PhysRevA.86.013604