An efficient quantum algorithm for generation of ab initio n-th order susceptibilities for non-linear spectroscopies

Fuente: arXiv
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Autores principales: Kharazi, Tyler, Stetina, Torin F., Ko, Liwen, Low, Guang Hao, Whaley, K. Birgitta
Formato: Preprint
Publicado: 2024
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author Kharazi, Tyler
Stetina, Torin F.
Ko, Liwen
Low, Guang Hao
Whaley, K. Birgitta
author_facet Kharazi, Tyler
Stetina, Torin F.
Ko, Liwen
Low, Guang Hao
Whaley, K. Birgitta
contents We develop and analyze a fault-tolerant quantum algorithm for computing $n$-th order response properties necessary for analysis of non-linear spectroscopies of molecular and condensed phase systems. We use a semi-classical description in which the electronic degrees of freedom are treated quantum mechanically and the light is treated as a classical field. The algorithm we present can be viewed as an implementation of standard perturbation theory techniques, focused on {\it ab initio} calculation of $n$-th order response functions. We provide cost estimates in terms of the number of queries to the block encoding of the unperturbed Hamiltonian, as well as the block encodings of the perturbing dipole operators. Using the technique of eigenstate filtering, we provide an algorithm to extract excitation energies to resolution $γ$, and the corresponding linear response amplitude to accuracy $ε$ using ${O}\left(N^{6}η^2{γ^{-1}ε^{-1}}\log(1/ε)\right)$ queries to the block encoding of the unperturbed Hamiltonian $H_0$, in double factorized representation. Thus, our approach saturates the Heisenberg $O(γ^{-1})$ limit for energy estimation and allows for the approximation of relevant transition dipole moments. These quantities, combined with sum-over-states formulation of polarizabilities, can be used to compute the $n$-th order susceptibilities and response functions for non-linear spectroscopies under limited assumptions using $\widetilde{O}\left({N^{5n+1}η^{n+1}}/{γ^nε}\right)$ queries to the block encoding of $H_0$.
format Preprint
id arxiv_https___arxiv_org_abs_2404_01454
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An efficient quantum algorithm for generation of ab initio n-th order susceptibilities for non-linear spectroscopies
Kharazi, Tyler
Stetina, Torin F.
Ko, Liwen
Low, Guang Hao
Whaley, K. Birgitta
Quantum Physics
We develop and analyze a fault-tolerant quantum algorithm for computing $n$-th order response properties necessary for analysis of non-linear spectroscopies of molecular and condensed phase systems. We use a semi-classical description in which the electronic degrees of freedom are treated quantum mechanically and the light is treated as a classical field. The algorithm we present can be viewed as an implementation of standard perturbation theory techniques, focused on {\it ab initio} calculation of $n$-th order response functions. We provide cost estimates in terms of the number of queries to the block encoding of the unperturbed Hamiltonian, as well as the block encodings of the perturbing dipole operators. Using the technique of eigenstate filtering, we provide an algorithm to extract excitation energies to resolution $γ$, and the corresponding linear response amplitude to accuracy $ε$ using ${O}\left(N^{6}η^2{γ^{-1}ε^{-1}}\log(1/ε)\right)$ queries to the block encoding of the unperturbed Hamiltonian $H_0$, in double factorized representation. Thus, our approach saturates the Heisenberg $O(γ^{-1})$ limit for energy estimation and allows for the approximation of relevant transition dipole moments. These quantities, combined with sum-over-states formulation of polarizabilities, can be used to compute the $n$-th order susceptibilities and response functions for non-linear spectroscopies under limited assumptions using $\widetilde{O}\left({N^{5n+1}η^{n+1}}/{γ^nε}\right)$ queries to the block encoding of $H_0$.
title An efficient quantum algorithm for generation of ab initio n-th order susceptibilities for non-linear spectroscopies
topic Quantum Physics
url https://arxiv.org/abs/2404.01454