Projection Monte Carlo Estimates Quantum Spin Glass Gaps

Researchers have discovered a surprising persistence in the limitations facing quantum annealing, a technique for solving complex optimization problems. A study led by L. Brodoloni, G.E. Astrakharchik, S. Giorgini, and S. Pilati of Università di Camerino and colleagues reveals that the inverse-gap distribution in two-dimensional quantum spin glasses develops a "fat tail with infinite variance" as system size increases. This finding indicates that unfavorable super-algebraic scaling of the minimum energy gap, previously reported in Nature 631, 749 (2024) for binary couplings, extends to systems with Gaussian disorder, suggesting a universal characteristic of 2D spin glasses. The team also found the all-to-all Sherrington-Kirkpatrick model exhibits a finite-variance distribution, offering a…