Predicting molecular vibronic spectra using time-domain analog quantum simulation

Spectroscopy is one of the most accurate probes of the molecular world. However, predicting molecular spectra accurately is computationally difficult because of the presence of entanglement between electronic and nuclear degrees of freedom. Although quantum computers promise to reduce this computati...

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Bibliographic Details
Published in:Chemical science (Cambridge) 2023-09, Vol.14 (35), p.9439-9451
Main Authors: MacDonell, Ryan J, Navickas, Tomas, Wohlers-Reichel, Tim F, Valahu, Christophe H, Rao, Arjun D, Millican, Maverick J, Currington, Michael A, Biercuk, Michael J, Tan, Ting Rei, Hempel, Cornelius, Kassal, Ivan
Format: Article
Language:English
Subjects:
Algorithms
Chemistry
Computing costs
Degrees of freedom
Eigenvectors
Molecular spectra
Molecular spectroscopy
Photoelectrons
Quantum computers
Quantum entanglement
Simulation
Spectrum analysis
Time domain analysis
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Summary:Spectroscopy is one of the most accurate probes of the molecular world. However, predicting molecular spectra accurately is computationally difficult because of the presence of entanglement between electronic and nuclear degrees of freedom. Although quantum computers promise to reduce this computational cost, existing quantum approaches rely on combining signals from individual eigenstates, an approach whose cost grows exponentially with molecule size. Here, we introduce a method for scalable analog quantum simulation of molecular spectroscopy: by performing simulations in the time domain, the number of required measurements depends on the desired spectral range and resolution, not molecular size. Our approach can treat more complicated molecular models than previous ones, requires fewer approximations, and can be extended to open quantum systems with minimal overhead. We present a direct mapping of the underlying problem of time-domain simulation of molecular spectra to the degrees of freedom and control fields available in a trapped-ion quantum simulator. We experimentally demonstrate our algorithm on a trapped-ion device, exploiting both intrinsic electronic and motional degrees of freedom, showing excellent quantitative agreement for a single-mode vibronic photoelectron spectrum of SO 2 . Analog quantum computers can calculate molecular vibronic spectra using time-domain simulation, with exponentially greater scalability than previous, frequency-domain approaches. An accurate, trapped-ion simulation of SO 2 validates the approach.
ISSN:2041-6520
2041-6539
DOI:10.1039/d3sc02453a