Orbital-optimized pair-correlated electron simulations on trapped-ion quantum computers

Abstract

Variational quantum eigensolvers (VQE) are among the most promising approaches for solving electronic structure problems on near-term quantum computers. A critical challenge for VQE in practice is that one needs to strike a balance between the expressivity of the VQE ansatz versus the number of quantum gates required to implement the ansatz, given the reality of noisy quantum operations on near-term quantum computers. In this work, we consider an orbital-optimized pair-correlated approximation to the unitary coupled cluster with singles and doubles (uCCSD) ansatz and report a highly efficient quantum circuit implementation for trapped-ion architectures. We show that orbital optimization can recover significant additional electron correlation energy without sacrificing efficiency through measurements of low-order reduced density matrices (RDMs). In the dissociation of small molecules, the method gives qualitatively accurate predictions in the strongly-correlated regime when running on noise-free quantum simulators. On IonQ's Harmony and Aria trapped-ion quantum computers, we run end-to-end VQE algorithms with up to 12 qubits and 72 variational parameters - the largest full VQE simulation with a correlated wave function on quantum hardware. We find that even without error mitigation techniques, the predicted relative energies across different molecular geometries are in excellent agreement with noise-free simulators.

References in corpus (34)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• A variational eigenvalue solver on a quantum processor
• The density-matrix renormalization group
• Hardware-efficient Variational Quantum Eigensolver for Small Molecules and Quantum Magnets
• Quantum Chemistry in the Age of Quantum Computing
• Simulated Quantum Computation of Molecular Energies
• An adaptive variational algorithm for exact molecular simulations on a quantum computer
• Extending the computational reach of a noisy superconducting quantum processor
• Hamiltonian Simulation by Qubitization
• Towards Quantum Chemistry on a Quantum Computer
• Hartree-Fock on a superconducting qubit quantum computer
• Robust determination of molecular spectra on a quantum processor
• Generalized Unitary Coupled Cluster Wavefunctions for Quantum Computation
• Optimal Quantum Circuits for General Two-Qubit Gates
• Encoding Electronic Spectra in Quantum Circuits with Linear T Complexity
• Quantum algorithms for electronic structure calculations: particle/hole Hamiltonian and optimized wavefunction expansions
• Even more efficient quantum computations of chemistry through tensor hypercontraction
• Quantum computing enhanced computational catalysis
• Error-mitigated digital quantum simulation
• A perspective on the current state-of-the-art of quantum computing for drug discovery applications
• Increasing the representation accuracy of quantum simulations of chemistry without extra quantum resources
• Doubling the size of quantum simulators by entanglement forging
• Is the Trotterized UCCSD Ansatz chemically well-defined?
• Mitigating depolarizing noise on quantum computers with noise-estimation circuits
• Quantum Orbital-Optimized Unitary Coupled Cluster Methods in the Strongly Correlated Regime: Can Quantum Algorithms Outperform their Classical Equivalents?
• Application-Oriented Performance Benchmarks for Quantum Computing
• Pair extended coupled cluster doubles
• Computational Investigations of the Lithium Superoxide Dimer Rearrangement on Noisy Quantum Devices
• Quantum Computational Quantification of Protein-Ligand Interactions
• Simulating quantum chemistry in the seniority-zero space on qubit-based quantum computers
• Quantum chemistry simulation of ground- and excited-state properties of the sulfonium cation on a superconducting quantum processor
• Generative Quantum Learning of Joint Probability Distribution Functions
• Randomized compiling for scalable quantum computing on a noisy superconducting quantum processor
• Quantum hardware calculations of periodic systems with partition-measurement symmetry verification: simplified models of hydrogen chain and iron crystals

Cited by in corpus (30)

• Chemistry Beyond the Scale of Exact Diagonalization on a Quantum-Centric Supercomputer
• Experimental quantum computational chemistry with optimised unitary coupled cluster ansatz
• A Hybrid Quantum Computing Pipeline for Real World Drug Discovery
• Overlap-ADAPT-VQE: Practical Quantum Chemistry on Quantum Computers via Overlap-Guided Compact Ansätze
• Statistical phase estimation and error mitigation on a superconducting quantum processor
• Solving an Industrially Relevant Quantum Chemistry Problem on Quantum Hardware
• Quantum subspace expansion in the presence of hardware noise
• Efficient and Robust Parameter Optimization of the Unitary Coupled-Cluster Ansatz
• Precision ground-state energy calculation for the water molecule on a superconducting quantum processor
• A Quantum Algorithmic Approach to Multiconfigurational Valence Bond Theory: Insights from Interpretable Circuit Design
• Distinguishing homolytic versus heterolytic bond dissociation of phenyl sulfonium cations with localized active space methods
• Characterization of overparametrization in the simulation of realistic quantum systems
• Comparison of encoding schemes for quantum computing of $S>1/2$ spin chains
• Quantum encoder for fixed Hamming-weight subspaces
• Cascaded variational quantum eigensolver algorithm
• Extending Quantum Computing through Subspace, Embedding and Classical Molecular Dynamics Techniques
• Efficient Quantum Cooling Algorithm for Fermionic Systems
• Photonic variational quantum eigensolver using entanglement measurements
• Quantum Machine Learning of Molecular Energies with Hybrid Quantum-Neural Wavefunction
• Demonstration of a variational quantum eigensolver with a solid-state spin system under ambient conditions
• Quantum Computing Beyond Ground State Electronic Structure: A Review of Progress Toward Quantum Chemistry Out of the Ground State
• Seniority-zero Linear Canonical Transformation Theory
• Bridging Quantum Computing and Nuclear Structure: Atomic Nuclei on a Trapped-Ion Quantum Computer
• State Specific Measurement Protocols for the Variational Quantum Eigensolver
• Photonic variational quantum eigensolver for NISQ-compatible quantum technology
• Quantum-Classical Auxiliary Field Quantum Monte Carlo with Matchgate Shadows on Trapped Ion Quantum Computers
• Adiabatic state preparation from general initial states
• Rovibrational energy levels of H${}_2$O by quantum computing
• Towards Compact Wavefunctions from Quantum-Selected Configuration Interaction
• Exploiting biased noise in variational quantum models