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 hybrid quantum-classical variational protocol that incorporates a feedback loop between a quantum simulator and a classical computer, and is experimentally realizable on near-term quantum devices of synthetic quantum systems. We find explicit protocols which prepare with perfect fidelities (i) the Greenberger-Horne-Zeilinger (GHZ) state, (ii) a quantum critical state, and (iii) a topologically ordered state, with $L$ variational parameters and physical runtimes $T$ that scale linearly with the system size $L$. We furthermore conjecture and support numerically that our protocol can prepare, with perfect fidelity and similar operational costs, the ground state of every point in the one dimensional transverse field Ising model phase diagram. Besides being practically useful, our results also illustrate the utility of such variational ans\"atze as good descriptions of non-trivial states of matter.
Cited by 3
Wen Wei Ho et al., Ultrafast variational simulation of nontrivial quantum states with long-range interactions
Phys. Rev. A 99, 052332 (2019) [Crossref]
Matthew J. S. Beach et al., Making trotters sprint: A variational imaginary time ansatz for quantum many-body systems
Phys. Rev. B 100, 094434 (2019) [Crossref]
Prahar Mitra et al., Cooling arbitrary near-critical systems using hyperbolic quenches
Phys. Rev. B 99, 104308 (2019) [Crossref]
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- 1 Wen Wei Ho,
- 2 3 Timothy H. Hsieh