Noncommutative geometry, extended W∞ algebra, and Grassmannian solitons in multicomponent quantum Hall systems

Noncommutative geometry governs the physics of quantum Hall (QH) effects. We introduce the Weyl ordering of the second quantized density operator to explore the dynamics of electrons in the lowest Landau level. We analyze QH systems made of N-component electrons at the integer filling factor ν=k⩽N. The basic algebra is the SU(N)-extended W_∞. A specific feature is that noncommutative geometry leads to a spontaneous development of SU(N) quantum coherence by generating the exchange Coulomb interaction. The effective Hamiltonian is the Grassmannian G_N,k sigma model, and the dynamical field is the Grassmannian G_N,k field, describing k(N-k) complex Goldstone modes and one kind of topological solitons (Grassmannian solitons).