IQIM Postdoctoral and Graduate Student Seminar

Special IQIM/CMP Seminar

Abstract: Hybrid classical-quantum algorithms aim at variationally solving optimization problems, using a feedback loop between a classical computer and a quantum co-processor, while benefitting from quantum resources. Here we present results from a theory-experiment collaboration in Innsbruck [1], demonstrating self-verifying, hybrid, variational quantum simulation of lattice models in condensed matter and high-energy physics.  Contrary to analog quantum simulation, this approach forgoes the requirement of realizing the targeted Hamiltonian directly in the laboratory, thus allowing the study of a wide variety of previously intractable target models. Our focus is the Lattice Schwinger model, a gauge theory of 1D quantum electrodynamics. Our quantum co-processor is a programmable, trapped-ion analog quantum simulator with up to 20 qubits, capable of generating families of entangled trial states respecting symmetries of the target Hamiltonian. We determine ground states and, by measuring variances of the Schwinger Hamiltonian, we provide algorithmic error bars for energies, thus addressing the long-standing challenge of verifying quantum simulation.

[1]  C.  Kokail, C.  Maier, R.  van  Bijnen, T.  Brydges,  M. K. Joshi,  P. Jurcevic, C. A.  Muschik, P. Silvi,  R. Blatt,  C.F. Roos and P. Zoller, Self-Verifying Variational Quantum Simulation of the Lattice Schwinger Model, arXiv:1810.03421