Topic: Minimal loop currents and cat states in doped Mott insulators

Speaker: Prof. Zheng-Yu Weng

Coordinates: Classroom 1201, 16:00, Friday,  December 12

Abstract: The behavior of dilute doped holes in an antiferromagnetic spin background is investigated using density matrix renormalization group (DMRG) and wavefunction variational Monte Carlo (VMC) methods. A strong correlation effect manifests as follows: A single unpaired hole generally exists in a cat state—a quantum superposition of a Landau quasiparticle and a non-quasiparticle component accompanied by minimal loop currents. These currents are associated with an intrinsic magnetization and angular momentum L_z=±1. When two holes are introduced, they bind into a tightly bound pair that suppresses the loop currents, forming a cat state superposition of a d-wave Cooper pair and a non-Cooper-pair component. In both cases, the off-diagonal mixing in the cat state provides the dominant energy contribution, reflecting the non-perturbative character of the doped Mott insulator. This novel picture remains valid up to finite doping levels, provided the antiferromagnetic correlation length exceeds the characteristic lattice scale (~4×4) for both the single-hole and two-hole cat states. We argue that the latter constitutes a minimal superconducting block.