The 5^{th} SMLQC seminar will be given by Weitang Li on April 27, 2023 (13:00 Paris | 19:00 Beijing | 07:00 New York).

## Title

TenCirChem: An Efficient Quantum Computational Chemistry Package for the NISQ Era

## Abstract

Quantum computational chemistry utilizes quantum computers to simulate chemical systems and has the potential to solve complex problems in chemistry and materials science that are difficult to handle with classical computers. In recent years, the quality and availability of quantum hardware have been constantly improving, making it possible to simulate microscopic chemical systems using quantum computers. However, most quantum computing experiments are still limited by a small number of qubits and very short circuit depth (Noisy Intermediate Scale Quantum, NISQ). In the foreseeable future, classical simulations of quantum algorithms will play an important role in studying and analyzing the performance and feasibility of quantum computational chemistry algorithms.

TenCirChem is an open-source Python library for simulating quantum computational chemistry algorithms. TenCirChem has an easy-to-use high-level interface that allows users to calculate molecular energy or simulate quantum dynamics using quantum algorithms with just a few lines of code. At the same time, TenCirChem has a high degree of flexibility and customizability for the rapid development and validation of new algorithms. By using compact quantum state and excitation operator representations, as well as a powerful TensorCircuit quantum circuit simulation software framework, TenCirChem demonstrates extremely high performance in simulating noiseless and noisy quantum circuits. For example, on a single GPU node, TenCirChem can be used to calculate the potential energy surface of a water molecule at the UCCSD/6-31G(d) level, where only the 1s orbital of the O atom is frozen, corresponding to a parameterized quantum circuit with 34 qubits and 565 independent parameters. The simulated equilibrium bond length has an error of only 0.01Å compared to experimental results. TenCirChem provides a convenient, easy-to-use, and powerful tool for researchers in the field of quantum computational chemistry to further develop and optimize quantum computational chemistry methods.

GitHub repo: __https://github.com/tencent-quantum-lab/TenCirChem__

WhitePaper: __https://arxiv.org/abs/2303.10825__

## Introduction to the speaker

Dr. Weitang Li is currently a research scientist at Tencent Quantum Lab. During Ph.D. Weitang Li is focused on leveraging tensor networks such as matrix product states to study quantum dynamics problems in novel organic materials. At Tencent Quantum Lab he develops both algorithm and software that enable quantum computers to solve chemistry problems.

**2017-2022:** Ph.D., Department of Chemistry, Tsinghua University. Supervisor: Prof. Zhigang Shuai.

**2022 till now:** Research scientist, Tencent Quantum Lab.