Noise reduction using past causal cones in variational quantum algorithms

Abstract

We introduce an approach to improve the accuracy and reduce the sample complexity of near term quantum-classical algorithms. We construct a simpler initial parameterized quantum state, or ansatz, based on the past causal cone of each observable, generally yielding fewer qubits and gates. We implement this protocol on a trapped ion quantum computer and demonstrate improvement in accuracy and time-to-solution at an arbitrary point in the variational search space. We report a $\sim 27\%$ improvement in the accuracy of the calculation of the deuteron binding energy and $\sim 40\%$ improvement in the accuracy of the quantum approximate optimization of the MAXCUT problem applied to the dragon graph $T_{3,2}$. When the time-to-solution is prioritized over accuracy, the former requires $\sim 71\%$ fewer measurements and the latter requires $\sim 78\%$ fewer measurements.

Added data availability statement, additional affiliation and grant acknowledgement

References in corpus (28)

• Quantum Computing in the NISQ era and beyond
• A variational eigenvalue solver on a quantum processor
• Hardware-efficient Variational Quantum Eigensolver for Small Molecules and Quantum Magnets
• Barren plateaus in quantum neural network training landscapes
• The theory of variational hybrid quantum-classical algorithms
• A Quantum Approximate Optimization Algorithm
• Quantum computational chemistry
• Multi-particle entanglement of hot trapped ions
• Demonstration of a small programmable quantum computer with atomic qubits
• Robust determination of molecular spectra on a quantum processor
• Quantum-Classical Computation of Schwinger Model Dynamics using Quantum Computers
• Cloud Quantum Computing of an Atomic Nucleus
• Quantum algorithms for electronic structure calculations: particle/hole Hamiltonian and optimized wavefunction expansions
• Verified Quantum Information Scrambling
• Algorithms for entanglement renormalization
• Quantum Implementation of Unitary Coupled Cluster for Simulating Molecular Electronic Structure
• Simulating Large Quantum Circuits on a Small Quantum Computer
• Witnessing eigenstates for quantum simulation of Hamiltonian spectra
• Arbitrary accuracy iterative phase estimation algorithm as a two qubit benchmark
• Tapering off qubits to simulate fermionic Hamiltonians
• Optimal quantum control of multi-mode couplings between trapped ion qubits for scalable entanglement
• Increasing the representation accuracy of quantum simulations of chemistry without extra quantum resources
• Basic circuit compilation techniques for an ion-trap quantum machine
• Generalized swap networks for near-term quantum computing
• Toward convergence of effective field theory simulations on digital quantum computers
• Ground-state energy estimation of the water molecule on a trapped ion quantum computer
• Robust entanglement renormalization on a noisy quantum computer
• Noise-resilient preparation of quantum many-body ground states

Cited by in corpus (4)

• Analytical Framework for Quantum Alternating Operator Ansätze
• Variationally Scheduled Quantum Simulation
• Noise-robust exploration of many-body quantum states on near-term quantum devices
• Preparing Renormalization Group Fixed Points on NISQ Hardware