End-to-end complexity for simulating the Schwinger model on quantum computers

• URL: http://arxiv.org/abs/2311.17388v3
• Date: Mon, 9 Sep 2024 06:59:19 GMT
• Title: End-to-end complexity for simulating the Schwinger model on quantum computers
• Authors: Kazuki Sakamoto, Hayata Morisaki, Junichi Haruna, Etsuko Itou, Keisuke Fujii, Kosuke Mitarai,
• Abstract summary: We propose an efficient implementation of block-encoding of the Schwinger model Hamiltonian. As an end-to-end application, we compute the vacuum persistence amplitude. Our results provide insights into predictions about the performance of quantum computers in the FTQC era.
• Score: 0.6449786007855248
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The Schwinger model is one of the simplest gauge theories. It is known that a topological term of the model leads to the infamous sign problem in the classical Monte Carlo method. In contrast to this, recently, quantum computing in Hamiltonian formalism has gained attention. In this work, we estimate the resources needed for quantum computers to compute physical quantities that are challenging to compute on classical computers. Specifically, we propose an efficient implementation of block-encoding of the Schwinger model Hamiltonian. Considering the structure of the Hamiltonian, this block-encoding with a normalization factor of $\mathcal{O}(N^3)$ can be implemented using $\mathcal{O}(N+\log^2(N/\varepsilon))$ T gates. As an end-to-end application, we compute the vacuum persistence amplitude. As a result, we found that for a system size $N=128$ and an additive error $\varepsilon=0.01$, with an evolution time $t$ and a lattice spacing a satisfying $t/2a=10$, the vacuum persistence amplitude can be calculated using about $10^{13}$ T gates. Our results provide insights into predictions about the performance of quantum computers in the FTQC and early FTQC era, clarifying the challenges in solving meaningful problems within a realistic timeframe.

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