Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Improving the Accuracy of Variational Quantum Eigensolvers with Fewer Qubits Using Orbital Optimization

Journal Article · · Journal of Chemical Theory and Computation
 [1];  [2];  [3]
  1. Duke Univ., Durham, NC (United States); Duke University
  2. Fudan Univ., Shanghai (China)
  3. Duke Univ., Durham, NC (United States)
Near-term quantum computers will be limited in the number of qubits on which they can process information as well as the depth of the circuits that they can coherently carry out. To date, experimental demonstrations of algorithms such as the Variational Quantum Eigensolver (VQE) have been limited to small molecules using minimal basis sets for this reason. In this work we propose incorporating an orbital optimization scheme into quantum eigensolvers wherein a parametrized partial unitary transformation is applied to the basis functions set in order to reduce the number of qubits required for a given problem. The optimal transformation is found by minimizing the ground state energy with respect to this partial unitary matrix. Through numerical simulations of small molecules up to 16 spin orbitals, we demonstrate that this method has the ability to greatly extend the capabilities of near-term quantum computers with regard to the electronic structure problem. Finally, we find that VQE paired with orbital optimization consistently achieves lower ground state energies than traditional VQE when using the same number of qubits and even frequently achieves lower ground state energies than VQE methods using more qubits.
Research Organization:
Duke Univ., Durham, NC (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE
Grant/Contract Number:
SC0019449
OSTI ID:
2280990
Journal Information:
Journal of Chemical Theory and Computation, Journal Name: Journal of Chemical Theory and Computation Journal Issue: 3 Vol. 19; ISSN 1549-9618
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

References (31)

P y SCF: the Python-based simulations of chemistry framework : The PySCF program
  • Sun, Qiming; Berkelbach, Timothy C.; Blunt, Nick S.
  • Wiley Interdisciplinary Reviews: Computational Molecular Science, Vol. 8, Issue 1 https://doi.org/10.1002/wcms.1340
journal September 2017
Resource-Efficient Chemistry on Quantum Computers with the Variational Quantum Eigensolver and the Double Unitary Coupled-Cluster Approach journal September 2020
Optimal Orbital Selection for Full Configuration Interaction (OptOrbFCI): Pursuing the Basis Set Limit under a Budget journal August 2020
Quantum Orbital Minimization Method for Excited States Calculation on a Quantum Computer journal July 2022
Hardware-efficient variational quantum eigensolver for small molecules and quantum magnets journal September 2017
A variational eigenvalue solver on a photonic quantum processor journal July 2014
An adaptive variational algorithm for exact molecular simulations on a quantum computer journal July 2019
Variational ansatz-based quantum simulation of imaginary time evolution journal September 2019
Quantum chemistry as a benchmark for near-term quantum computers journal November 2019
Determining eigenstates and thermal states on a quantum computer using quantum imaginary time evolution journal November 2019
Unbiasing fermionic quantum Monte Carlo with a quantum computer journal March 2022
Quantum simulation of electronic structure with a transcorrelated Hamiltonian: improved accuracy with a smaller footprint on the quantum computer journal January 2020
Strategies for quantum computing molecular energies using the unitary coupled cluster ansatz journal October 2018
A state-averaged orbital-optimized hybrid quantum–classical algorithm for a democratic description of ground and excited states journal January 2021
Improving the accuracy and efficiency of quantum connected moments expansions * journal June 2021
Qubit-ADAPT-VQE: An Adaptive Algorithm for Constructing Hardware-Efficient Ansätze on a Quantum Processor journal April 2021
Leveraging Small-Scale Quantum Computers with Unitarily Downfolded Hamiltonians journal April 2023
Hybrid quantum-classical hierarchy for mitigation of decoherence and determination of excited states journal April 2017
Accelerated Variational Quantum Eigensolver journal April 2019
Quantum Computation of Electronic Transitions Using a Variational Quantum Eigensolver journal June 2019
Subspace-search variational quantum eigensolver for excited states journal October 2019
Orbital optimized unitary coupled cluster theory for quantum computer journal September 2020
Quantum equation of motion for computing molecular excitation energies on a noisy quantum processor journal October 2020
Reduced density matrix sampling: Self-consistent embedding and multiscale electronic structure on current generation quantum computers journal September 2021
Orders of magnitude increased accuracy for quantum many-body problems on quantum computers via an exact transcorrelated method journal June 2023
Increasing the Representation Accuracy of Quantum Simulations of Chemistry without Extra Quantum Resources journal January 2020
Quantum computational chemistry journal March 2020
Simulated Quantum Computation of Molecular Energies journal September 2005
A Limited Memory Algorithm for Bound Constrained Optimization journal September 1995
A New First-Order Algorithmic Framework for Optimization Problems with Orthogonality Constraints journal January 2018
Variational Quantum Computation of Excited States journal July 2019

Similar Records

Quantum Simulation of Molecular Electronic States with a Transcorrelated Hamiltonian: Higher Accuracy with Fewer Qubits
Journal Article · Thu Aug 18 20:00:00 EDT 2022 · Journal of Chemical Theory and Computation · OSTI ID:2318949