Unitary Partitioning Approach to the Measurement Problem in the Variational Quantum Eigensolver Method
Nov 20, 20196 pages
Published in:
- J.Chem.Theor.Comput. 16 (2019) 1, 190-195
- Published: Nov 20, 2019
Citations per year
Abstract: (ACS)
To obtain estimates of electronic energies, the Variational Quantum Eigensolver (VQE) technique performs separate measurements for multiple parts of the system Hamiltonian. Current quantum hardware is restricted to projective single-qubit measurements, and, thus, only parts of the Hamiltonian that form mutually qubit-wise commuting groups can be measured simultaneously. The number of such groups in the electronic structure Hamiltonians grows as N4, where N is the number of qubits, thereby putting serious restrictions on the size of the systems that can be studied. Using a partitioning of the system Hamiltonian as a linear combination of unitary operators, we found a circuit formulation of the VQE algorithm that allows one to measure a group of fully anticommuting terms of the Hamiltonian in a single series of single-qubit measurements. Numerical comparison of the unitary partitioning to previously used grouping of Hamiltonian terms based on their qubit-wise commutativity is consistent with an N-fold reduction in the number of measurable groups.- Algorithms
- Circuits
- Hamiltonians
- Mathematical methods
- Show More
- unitarity: operator
- Hamiltonian
- variational quantum eigensolver
- measurement theory
- mathematical methods
References(44)
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