  We present lattice calculations for the ground state energy of dilute neutron
matter at next-to-leading order in chiral effective field theory. This study
follows a series of recent papers on low-energy nuclear physics using chiral
effective field theory on the lattice. In this work we introduce an improved
spin- and isospin-projected leading-order action which allows for a
perturbative treatment of corrections at next-to-leading order and smaller
estimated errors. Using auxiliary fields and Euclidean-time projection Monte
Carlo, we compute the ground state of 8, 12, and 16 neutrons in a periodic
cube, covering a density range from 2% to 10% of normal nuclear density.
