**CANCELED** Variational quantum algorithms: obstacles and opportunities
MATHEMATICAL PICTURE LANGUAGE
Sergey Bravyi - IBM and Perimeter Institute
Variational quantum algorithms such as VQE or QAOA aim to simulate low-energy properties of quantum many-body systems or find approximate solutions of combinatorial optimization problems. Such algorithms employ variational states generated by low-depth quantum circuits to minimize the expected value of a quantum or classical Hamiltonian. In this talk I will explain how to use general structural properties of variational states such as locality and symmetry to derive upper bounds on their computational power and, in certain cases, rule out potential quantum speedups. To overcome some of these limitations, we introduce the correlation rounding method and a recursive Quantum Approximate Optimization Algorithm.
Based on arXiv:1909.11485 and arXiv:1910.08980