A worm algorithm is proposed for the two-dimensional spin glasses. The method
is based on a low-temperature expansion of the partition function. The
low-temperature configurations of the spin glass on square lattice can be
viewed as strings connecting pairs of frustrated plaquettes. The worm algorithm
directly manipulates these strings. It is shown that the worm algorithm is as
efficient as any other types of cluster or replica-exchange algorithms. The
worm algorithm is even more efficient if free boundary conditions are used. We
obtain accurate low-temperature specific heat data consistent with a form c =
T^{-2} exp(-2J/(k_BT)), where T is temperature and J is coupling constant, for
the +/-J two-dimensional spin glass.Comment: 4 pages, 3 figure