Abstract:

For quantum critical spin chains without disorder, it is known that the entanglement of a segment of N>>1 spins with the remainder is log N times a prefactor determined by the central charge of the associated conformal field theory.  For a class of strongly random quantum spin chains, the same logarithmic scaling holds for mean entanglement at criticality and defines a critical entropy equivalent to central charge in the pure case.  In my talk I'll introduce the real-space RG as it applies to the relevant models (Transverse field Ising model, Heisenberg, and the non-abelian golden chain), review the derivation of the entanglement entropy, and discuss its consequences.

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