Quantum Equation of Motion with Orbital Optimization for Computing Molecular Properties in Near-Term Quantum Computing

Journal of Chemical Theory and Computation, Год журнала: 2024, Номер 20(9), С. 3613 - 3625

Опубликована: Май 3, 2024

Determining the properties of molecules and materials is one premier applications quantum computing. A major question in field how to use imperfect near-term computers solve problems practical value. Inspired by recently developed variants counterpart equation-of-motion (qEOM) approach orbital-optimized variational eigensolver (oo-VQE), we present a algorithm (oo-VQE-qEOM) for calculation molecular computing expectation values on computer. We perform noise-free simulations BeH2 series STO-3G/6-31G/6-31G* basis sets H4 H2O 6-31G using an active space four electrons spatial orbitals (8 qubits) evaluate excitation energies, electronic absorption, and, twisted H4, circular dichroism spectra. demonstrate that proposed can reproduce results conventional classical CASSCF calculations these systems.

Язык: Английский

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Understanding and mitigating noise in molecular quantum linear response for spectroscopic properties on quantum computers

Chemical Science, Год журнала: 2025, Номер 16(10), С. 4456 - 4468

Опубликована: Янв. 1, 2025

The promise of quantum computing to circumvent the exponential scaling chemistry has sparked a race develop algorithms for architecture. However, most works neglect quantum-inherent shot noise, let alone effect current noisy devices. Here, we present comprehensive study linear response (qLR) theory obtaining spectroscopic properties on simulated fault-tolerant computers and present-day near-term hardware. This work introduces novel metrics analyze predict origins noise in algorithm, proposes an Ansatz-based error mitigation technique, reveals significant impact Pauli saving reducing measurement costs subspace methods. Our hardware results using up cc-pVTZ basis set serve as proof principle absorption spectra general approach with accuracy classical multi-configurational Importantly, our exemplify that substantial improvements rates speed are necessary lift computational from concept actual field.

Язык: Английский

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Exact Ansatz of Fermion-Boson Systems for a Quantum Device

Physical Review Letters, Год журнала: 2024, Номер 133(8)

Опубликована: Авг. 23, 2024

We present an exact Ansatz for the eigenstate problem of mixed fermion-boson systems that can be implemented on quantum devices. Based a generalization electronic contracted Schrödinger equation (CSE), our approach guides trial wave function to ground state any arbitrary Hamiltonian by directly measuring residuals CSE device. Unlike density functional and coupled cluster theories applied electron-phonon or electron-photon systems, accuracy is not limited unknown exchange-correlation uncontrolled form exponential Ansatz. To test performance method, we study Tavis-Cummings model, commonly used in polaritonic chemistry. Our results demonstrate powerful tool development algorithms solving general many-body problems.

Язык: Английский

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Simulating Vibronic Spectra by Direct Application of Doktorov Formulas on a Superconducting Quantum Simulator

The Journal of Physical Chemistry A, Год журнала: 2024, Номер 128(21), С. 4369 - 4377

Опубликована: Май 16, 2024

In this work, a direct quantum implementation of the Doktorov formulas for calculating vibronic spectrum molecules under harmonic approximation is presented. It applied to three-atom H2O, SO2, ClO2, HS2, and ZnOH. The method solves classically hard problem estimating Franck–Condon (FC) factors by using Duschinsky matrices as only input via circuit. This has advantage avoiding basis changes, artificial squeezing parameters, symmetry dependencies. other words, it general that can easily be generalized bigger molecules. results are compared with algorithms classical anharmonic algorithms. Furthermore, circuit requirements studied in order estimate its applicability on real superconducting hardware.

Язык: Английский

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Unitary Block-Correlated Coupled Cluster Ansatz Based on the Generalized Valence Bond Wave Function for Quantum Simulation

Journal of Chemical Theory and Computation, Год журнала: 2025, Номер unknown

Опубликована: Апрель 22, 2025

Strongly correlated (SC) systems present significant challenges for classical quantum chemistry methods. Quantum computing, particularly the variational eigensolver (VQE), offers a promising framework to address these by inherently supporting exponentially large configuration spaces. However, its application SC remains limited due single-reference nature of widely used ansatzes such as unitary coupled cluster (UCC). To this challenge, we propose generalized valence bond-based block (GVB-UBCCC) method. This novel ansatz incorporates multiconfigurational bond (GVB) and accuracy (BCCC) methods, making it well-suited systems. We have implemented GVB-UBCCC method with up two-block correlation (GVB-UBCCC2) applied investigate ground-state energies several systems, including H4, water dimer, N2H2, S6, at most described 24 qubits. Our approach demonstrates that GVB-UBCCC2 can achieve more accurate than UCCSD in cases while requiring only O(N2) gates parameters, opposed O(N4) scaling UCCSD. The results highlight effectiveness potential advantages

Язык: Английский

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Toward Accurate Calculation of Excitation Energies on Quantum Computers with ΔADAPT-VQE: A Case Study of BODIPY Derivatives

The Journal of Physical Chemistry Letters, Год журнала: 2024, Номер 15(28), С. 7111 - 7117

Опубликована: Июль 2, 2024

Quantum chemistry simulations offer a cost-effective way to computationally design BODIPY photosensitizers. However, accurate predictions of excitation energies pose challenge for time-dependent density functional theory and equation-of-motion coupled-cluster singles doubles methods. By contrast, reliable can be achieved by multireference quantum methods; unfortunately, their computational cost increases exponentially with the number electrons. Alternatively, computing holds potential an exact simulation photophysical properties in more efficient way. Herein, we introduce state-specific ΔUCCSD-VQE (unitary doubles-variational eigensolver) ΔADAPT-VQE methods which electronically excited state is calculated via non-Aufbau configuration. We show six derivatives that proposed predict are good agreement those from experiments. Due its performance simplicity, believe ΔADAPT will become useful approach photosensitizers on near-term devices.

Язык: Английский

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Divergences in classical and quantum linear response and equation of motion formulations

The Journal of Chemical Physics, Год журнала: 2024, Номер 161(12)

Опубликована: Сен. 25, 2024

Calculating molecular properties using quantum devices can be performed through the linear response (qLR) or, equivalently, equation of motion (qEOM) formulations. Different parameterizations qLR and qEOM are available, namely naïve, projected, self-consistent, state-transfer. In naïve projected parameterizations, metric is not identity, we show that it depends on redundant orbital rotations. This dependency may lead to divergences in excitation energies for certain choices rotation parameters an idealized noiseless setting. Furthermore, this leads a significant variance when calculations include statistical noise from finite sampling.

Язык: Английский

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Unitary coupled-cluster for quantum computation of molecular properties in a strong magnetic field

The Journal of Chemical Physics, Год журнала: 2023, Номер 159(20)

Опубликована: Ноя. 22, 2023

In truncated coupled-cluster (CC) theories, non-variational and/or generally complex ground-state energies can occur. This is due to the non-Hermitian nature of similarity transformed Hamiltonian matrix in combination with CC truncation. For chemical problems that deal real-valued matrices, rarely However, for complex-valued such as those arise presence strong magnetic fields, be regularly observed unless certain symmetry conditions are fulfilled. Therefore, it desirable pursue methods guaranteed give upper-bound, energies. this work, we present first application unitary systems a field. achieved utilizing variational quantum eigensolver algorithm applied singles and doubles (UCCSD) method. We benchmark method on H2 molecule field then calculate UCCSD H4 function both geometry angle. show while standard CCSD yield not an upper-bound true energy, always results also imaginary components energy largest strongly correlated region. Last, calculations capture large percentage correlation energy.

Язык: Английский

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Variational Quantum Eigensolver Boosted by Adiabatic Connection

The Journal of Physical Chemistry A, Год журнала: 2024, Номер 128(3), С. 687 - 698

Опубликована: Янв. 12, 2024

In this work, we integrate the variational quantum eigensolver (VQE) with adiabatic connection (AC) method for efficient simulations of chemical problems on near-term computers. Orbital-optimized VQE methods are employed to capture strong correlation within an active space, and classical AC corrections recover dynamical effects comprising electrons outside space. On two challenging strongly correlated problems, namely, dissociation N2 electronic structure tetramethyleneethane biradical, show that combined VQE-AC approach enhances performance dramatically. Moreover, since do not bring any additional requirements resources or measurements, they can actually boost algorithms. Our work paves way toward real-life

Язык: Английский

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Variational Quantum Eigenvalue Solver Algorithm Utilizing Bridge-inspired Quantum Circuits and a Gradient Filter Module

Computer Physics Communications, Год журнала: 2024, Номер unknown, С. 109117 - 109117

Опубликована: Янв. 1, 2024

Язык: Английский

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