Preprint

PUBDB-2024-07801

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Concurrent VQE for Simulating Excited States of the Schwinger Model

Guo, Y. (Corresponding author)DESY* ; Angelides, T. (Corresponding author)DESY* ; Jansen, K.DESY* ; Kühn, S.DESY*

2024

This record in other databases:  

Report No.: arXiv:2407.15629

Abstract: This work explores the application of the concurrent variational quantum eigensolver (cVQE) for computing excited states of the Schwinger model. By designing suitable ansatz circuits utilizing universal SO(4) or SO(8) qubit gates, we demonstrate how to efficiently obtain the lowest two, four, and eight eigenstates with one, two, and three ancillary qubits for both vanishing and non-vanishing background electric field cases. Simulating the resulting quantum circuits classically with tensor network techniques, we demonstrate the capability of our approach to compute the two lowest eigenstates of systems with up to $\mathcal{O}(100)$ qubits. Given that our method allows for measuring the low-lying spectrum precisely, we also present a novel technique for estimating the additive mass renormalization of the lattice based on the energy gap. As a proof-of-principle calculation, we prepare the ground and first-excited states with one ancillary and four physical qubits on quantum hardware, demonstrating the practicality of using the cVQE to simulate excited states.

Note: 21 pages, 17 figures, 3 tables, comments are welcome!

---

Contributing Institute(s):

1. Centre f. Quantum Techno. a. Application (CQTA)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)
2. QUEST - QUantum computing for Excellence in Science and Technology (101087126) (101087126)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2024

---