Dr. Jonathan Classen-Howes
Oxford University
Universal Freezing Transitions of Dipole-Conserving Chains
Location: Zoom
Host: Calvin Pozderac
Abstract: I shall present on a general class of quantum chains with range-k interactions subject to the conservation of a total charge and its dipole moment. These systems undergo a “freezing” transition between strongly fragmented (non-thermalising) and weakly fragmented (thermalising) phases as the charge filling v is varied. I will show that these transitions occur at a critical charge filling of v_c = (k−2)^(-1) which is “universal” as it is independent of the on-site Hilbert space dimension d. To this end, I will analytically prove that for any dimension d, any state at v < v_c hosts a finite density of sites belonging to “blockages”: local regions across which transport of charge and dipole moment cannot occur. I will demonstrate that this implies strong fragmentation of typical symmetry sectors into Krylov sectors which each form an exponentially vanishing fraction of the total sector. I will present numerical evidence that the model is in its weakly fragmented phase for v>v_c, where typical symmetry sectors are dominated by a single large Krylov subspace and almost all states are blockage-free. I will also discuss the underlying reasons for why the critical filling is d-independent, as well as the impact of blockages on the dynamical evolution of typical states.
Zoom Details:
September 23rd at 10:00 AM ET (3:00PM Oxford)
https://osu.zoom.us/j/99109497184?pwd=OMlH7aFJxTG9Nu9aSuDfFbcP5Hawep.1
Meeting ID: 991 0949 7184
Password: 180405
