We describe a quantum circuit that produces a highly entangled state of N qubits from which one can efficiently compute expectation values of local observables. This construction yields a variational ansatz for quantum many-body states that can be regarded as a generalization of the multi-scale entanglement renormalization ansatz (MERA), and to which we refer as the branching MERA. In a lattice system in D dimensions, the scaling of entanglement of a region of size L^D in the branching MERA is not subject to restrictions such as a boundary law L^{ D-1}, but can be proportional to the size of the region, as we demonstrate numerically for D=1,2 dimensions.
Categories: quant-ph