Ab initio many-fermion structure calculations on a quantum computer

TL;DR

This paper introduces a new hybrid quantum-classical method for calculating the complete bound-state spectrum and angular momentum of many-fermion systems, demonstrated on oxygen-20 with realistic interactions.

Contribution

It presents a novel approach that overcomes previous limitations by providing full spectral and structural information, including total angular momentum, for complex quantum many-body problems.

Findings

Successfully computed the bound-state spectrum of ${^{20}O}$

Determined the total angular momentum $J$ for each eigenstate

Applicable to diverse fields like nuclear physics and hadron spectra

Abstract

To overcome the limitations of existing algorithms for solving self-bound quantum many-body problems -- such as those encountered in nuclear and particle physics -- that access only a restricted subset of energy levels and provide limited structural information, we introduce and demonstrate a novel quantum-classical approach capable of resolving the complete bound-state spectrum. This method also provides the total angular momentum $J$ associated with each eigenstate. Our approach is based on expressing the Hamiltonian in second-quantized form within a novel input model combined with a scan scheme, enabling broad applicability to configuration-interaction calculations across diverse fields. We apply this hybrid method to compute, for the first time, the bound-state spectrum together with corresponding $J$ values of ${^{20}O}$ using a realistic strong-interaction Hamiltonian. Our approach applies to hadron spectra and $J$ values solved in the relativistic Basis Light-Front Quantization approach.