Efficient preparation of non-trivial quantum states using the Quantum Approximate Optimization Algorithm

摘要: We provide an efficient and general route for preparing non-trivial quantum states that are not adiabatically connected to unentangled product states. Our approach is a variant of the 'Quantum Approximate Optimization Algorithm' (QAOA) [E. Farhi et al., arXiv:1411.4028] experimentally realizable on near-term simulators synthetic systems. As proof concept, our yields explicit protocols which prepare with perfect fidelities (i) Greenberger-Horne-Zeilinger (GHZ) state, (ii) critical (iii) topologically ordered all $p = L/2$ iterations algorithm physical runtimes $T$ scale linearly system size $L$, i.e. $T \sim L$. The protocol additionally able ground antiferromagnetic Heisenberg chains very good fidelities. Besides being practically useful, results also illustrate utility QAOA-type circuits as variational wavefunctions matter.