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

• Main Authors: Ziems, Karl Michael, Kjellgren, Erik Rosendahl, Sauer, Stephan P. A, Kongsted, Jacob, Coriani, Sonia
• Format: Journal Article
• Language: English
• Published: 17.08.2024
• Subjects: Physics - Chemical Physics; Physics - Computational Physics; Physics - Quantum Physics
• DOI: 10.48550/arxiv.2408.09308

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