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**A class of quantum many-body states that can be efficiently simulated**

G. Vidal

(Submitted on 12 Oct 2006)

We introduce the multi-scale entanglement renormalization ansatz (MERA), an efficient representation of certain quantum many-body states on a D-dimensional lattice. Equivalent to a quantum circuit with logarithmic depth and distinctive causal structure, the MERA allows for an exact evaluation of local expectation values. It is also the structure underlying entanglement renormalization, a coarse-graining scheme for quantum systems on a lattice that is focused on preserving entanglement.

http://arxiv.org/abs/quant-ph/0610099

Just trying to follow some of the Condensed Matter and Area Laws Papers of late. Find myself re-reading Swingle's paper http://arxiv.org/abs/0905.1317 and the one above - which as I understand it first introduced the MERA process - which seems to hinge especially on these things called "disentanglers". I'm hoping someone can answer the following question without too much effort:

Are disentanglers (and I guess isometries as well) just part of the ansatz (guess). In other words without speculating on what could cause them - they are key parts of a proposed theory which is Ansatz. Or is there a more extensive history to them conceptually. If MERA accurately models Quantum Space-Time Geometry where would one suggest the disentanglers come from? Not where literally, but what mechanism are they rooted in. What physical notion supports their existence and function. Is related to the negative curvature of Ads?

Hope that makes a little sense.