GC/ITS seminar tomorrow (10/6)at noon: K. Beach, Very slow spin dynamics in a ferromagnetic chain with three-body interactions

[vadim.o...@gmail.com]

Dear all, it's been a long time coming but our condmat seminar is finally awaking from its slumber, in a new spot, on Tue@ noon

Kevin Beach will give us an overview of interesting results on  Fredkin chains 

https://us02web.zoom.us/j/89705106738?pwd=UlYrb2NPMmx2TS80RDIrNmgrWHlMQT09  

K. Beach

Very slow spin dynamics in a ferromagnetic chain with three-body interactions

I will discuss the case of spin-half chains whose interactions are pairwise ferromagnetic but contingent on the spin state at a third adjacent site. The resulting family of Hamiltonians, which includes the Fredkin spin chain and its t-deformed cousins, is frustration-free but highly nontrivial. The phase diagram includes states with large entanglement and unusually slow dynamics. At the Fredkin point, the low-energy physics is that of a strong xy ferromagnet with gapless excitations. The excitations, however, are distinct from conventional spin waves. Instead, the object of interest is a delocalized bonded spin pair that must drag itself through the effective medium of the background spins: there is a topological character that must be preserved during the motion that induces a form of dynamical jamming. In addition to some new analytical results, I will present numerical results that explore the broader phase diagram (DMRG) and that directly simulate the quantum dynamics of the various excitations (QMC).