Fig. 6: Construction of the gauge-invariant configurations for the local sites.
From: Lattice quantum electrodynamics in (3+1)-dimensions at finite density with tensor networks
a Representation of the gauge field in terms of two species of Dirac modes in the sector with a total number of fermions equal to two. b Generic state of the local site composed by the matter degrees of freedom and six half-links along with the three spatial directions. On each half-link, the coefficients kj ∈ {0, 1, 2} define the fermionic modes. c Examples of gauge-invariant configurations for even and odd sites. Due to the use of staggered-fermions, the presence/absence of a fermion in an even/odd site represents the presence of a charge/anti-charge.
