Qubit coupled cluster singles and doubles variational quantum eigensolver ansatz for electronic structure calculations

Xia, Rongxin; Kais, Sabre

doi:10.1088/2058-9565/abbc74

Cited by 66 publications

(67 citation statements)

References 37 publications

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“…We call these unitary operations "qubit excitation evolutions". Qubit excitation evolutions [23,[44][45][46] are unitary evolutions of "qubit excitation operators", which satisfy "qubit commutation relations" [45,46]. Qubit excitation evolutions can be implemented by circuits that act on fixed numbers of qubits, as opposed to fermionic excitation evolutions, which act on a number of qubits that scales at least as O(log 2 N MO ) with the number of molecular spin-orbitals N MO (see Sec.…”

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confidence: 99%

Iterative qubit-excitation based variational quantum eigensolver

Yordanov¹,

Armaos²,

Barnes³

et al. 2021

Preprint

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Molecular simulations with the variational quantum eigensolver (VQE) are a promising application for emerging noisy intermediate-scale quantum computers. Constructing accurate molecular ansatze that are easy to optimize and implemented by shallow quantum circuits is crucial for the successful implementation of such simulations. Ansatze are, generally, constructed as series of fermionic-excitation evolutions. Instead, we demonstrate the usefulness of constructing ansatze with ``qubit-excitation evolutions', which, contrary to fermionic excitation evolutions, obey ``qubit commutation relations'. We show that qubit excitation evolutions, despite the lack of some of the physical features of fermionic excitation evolutions, accurately construct ansatze, while requiring asymptotically fewer gates. Utilizing qubit excitation evolutions, we introduce the iterative qubit excitation based VQE (IQEB-VQE) algorithm. The IQEB-VQE performs molecular simulations using a problem-tailored ansatz, grown iteratively by appending evolutions of single and double qubit excitation operators. By performing numerical simulations for small molecules, we benchmark the IQEB-VQE, and compare it against other competitive VQE algorithms. In terms of circuit efficiency and time complexity, we find that the IQEB-VQE systematically outperforms the previously most circuit-efficient, practically scalable VQE algorithms.

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confidence: 99%

Iterative qubit-excitation based variational quantum eigensolver

Yordanov¹,

Armaos²,

Barnes³

et al. 2021

Preprint

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show abstract

“…It was shown numerically in ref. 113 that using this method, one can achieve similar accuracy as UCCSD for different systems (BeH 2 , H 2 O, N 2 , H 4 and H 6 ), indicating that removal of parity terms has little effect on energy calculations for small molecular systems.…”

Section: Ucc-based Ansätze On Quantum Computersmentioning

confidence: 93%

“…An alternative to constructing the ansatz using unitary operations with Pauli strings as generators, is to use particle preserving exchange gates. 113 Previously, these exchange gates have been called qubit excitations, 80 particle-exchange gates, 84 “A” gates 114 or orbital-rotations. 74 For example, a single particle conservation exchange gates (or Qubit excitation) is defined as:where θ is the rotation parameter and the qubit i is partially excited to the qubit a .…”

Section: Ucc-based Ansätze On Quantum Computersmentioning

confidence: 99%

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A quantum computing view on unitary coupled cluster theory

et al. 2022

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“…Cryptography [3,4], drug design and discovery [5][6][7], the study of complex molecular structures [8,9], and optimization and financial forecasting [10,11] are some areas that hope to benefit from the construction of a quantum computer. However, today's quantum computers are highly susceptible to noise, which can lead to errors in the calculations they perform [12].…”

Section: Introductionmentioning

confidence: 99%

QuantumSkynet: A High Dimensional Quantum Computing Simulator

Giraldo-Carvajal

2020

Frontiers in Optics / Laser Science

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The use of classical computers to simulate quantum computing has been successful in aiding the study of quantum algorithms and circuits that are too complex to examine analytically. Current implementations of quantum computing simulators are limited to two-level quantum systems. Recent advances in high-dimensional quantum computing systems have demonstrated the viability of working with multilevel superposition and entanglement. These advances allow an agile increase in the number of dimensions of the system while maintaining quantum entanglement, achieving higher encoding of information and making quantum algorithms less vulnerable to decoherence and computational errors. In this paper, we introduce QuantumSkynet, a novel high-dimensional cloud-based quantum computing simulator. This platform allows simulations of qudit-based quantum algorithms. We also propose a unified generalization of high-dimensional quantum gates, which are available for simulations in QuantumSkynet. Finally, we report simulations and their results for qudit-based versions of the Deutsch-Jozsa and quantum phase estimation algorithms using QuantumSkynet.

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Qubit coupled cluster singles and doubles variational quantum eigensolver ansatz for electronic structure calculations

Cited by 66 publications

References 37 publications

Iterative qubit-excitation based variational quantum eigensolver

Iterative qubit-excitation based variational quantum eigensolver

A quantum computing view on unitary coupled cluster theory

QuantumSkynet: A High Dimensional Quantum Computing Simulator

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