### Session P5: Entanglement Entropy in Condensed Matter Physics

11:15 AM–1:39 PM, Wednesday, March 7, 2007
Colorado Convention Center Room: Korbel 1A-1B

Chair: Eduardo Fradkin, University of Illinois at Urbana-Champaign

Abstract ID: BAPS.2007.MAR.P5.3

### Abstract: P5.00003 : Entanglement entropy of quantum-critical spin chains with strong randomness

12:27 PM–1:03 PM

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#### Author:

Gil Refael
(California Institute of Technology)

For disorder-free critical quantum spin chains, the entanglement of a segment of $N\gg 1$ spins with the remainder scales as $log_2 N$, with a prefactor fixed by the central charge of the associated conformal field theory. The mean entanglement entropy of quantum spin chains with randomness follows the same logarithmic scaling, and provides a universal critical entropy, which is equivalent to the central charge in the pure case. In my talk I will explore the origin and derivation of the universal entanglment entropy of the random spin-1/2 Heiseneberg model in the random-singlet phase, as well as that of the random spin-1 Heisenberg chain at the breakdown of its Haldane phase. The entanglement of these and related infinite-randomness fixed points makes it possible to speculate on possible extensions of the c-theorem of CFTs to the realm of systems with strong randomness.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.P5.3