Melting of a Bosonic Mott Insulator in Kagome Optical Lattices with Sign-Inverted Hopping

Abstract

Using the discrete truncated Wigner approximation (dTWA), we investigate the nonequilibrium dynamics of ultracold bosons confined in optical kagome lattices, focusing on both unfrustrated positive and frustrated negative hopping regimes. We consider a protocol in which the system is initialized in a Mott insulating state at unit filling, and the hopping amplitude is gradually increased from zero. For positive hopping, the melting of the Mott insulator is accompanied by the emergence of a sharp peak in the momentum distribution at the $\Gamma$ point of the lowest band, signaling the onset of superfluidity. In contrast, for negative hopping, the Mott insulator melts into a highly nontrivial state without long-range phase coherence, characterized instead by a broad momentum distribution within the flat band, consistent with recent experimental observations. These results demonstrate the applicability of dTWA to highly frustrated quantum systems and offer a new route for numerically exploring the dynamics of frustrated quantum magnets.