Figure 1
APS/Alan Stonebraker

Figure 1: (a) Spin configurations on a tetrahedra that obey the “ice-rules.” (b) Proposed low-temperature phases of a quantum spin ice consist of a magnetically polarized high-field phase with usual spin-flip excitations (shown at right) and a low-field phase consisting of “emergent” dynamical photons (shown by a wavy line) and electric and magnetic charges (shown schematically as plus and minus charges with emanating electric fields and north (N) and south (S) poles with emanating magnetic fields).