537 research outputs found
Entanglement in low-energy states of the random-hopping model
We study the low-energy states of the 1D random-hopping model in the strong
disordered regime. The entanglement structure is shown to depend solely on the
probability distribution for the length of the effective bonds , whose
scaling and finite-size behavior are established using renormalization-group
arguments and a simple model based on random permutations. Parity oscillations
are absent in the von Neumann entropy with periodic boundary conditions, but
appear in the higher moments of the distribution, such as the variance. The
particle-hole excited states leave the bond-structure and the entanglement
untouched. Nonetheless, particle addition or removal deletes bonds and leads to
an effective saturation of entanglement at an effective block size given by the
expected value for the longest bond
From conformal to volume-law for the entanglement entropy in exponentially deformed critical spin 1/2 chains
An exponential deformation of 1D critical Hamiltonians gives rise to ground
states whose entanglement entropy satisfies a volume-law. This effect is
exemplified in the XX and Heisenberg models. In the XX case we characterize the
crossover between the critical and the maximally entangled ground state in
terms of the entanglement entropy and the entanglement spectrum.Comment: Accepted for the Special Issue: Quantum Entanglement in Condensed
Matter Physics. 11 pages, 9 figures (with enhanced size to focus on the
details) and new reference
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