Using quantum computers to simulate a toy problem of laser-plasma interactions

Yuan Shi

Lawrence Livermore National Laboratory

Thursday, September 9, 2021

3:00pm

Virtual

PSFC Seminars

Abstract: Quantum computing may lead to game-changing capabilities for science and technology. However, many practical problems are classical, and exactly how quantum systems can be used to solve classical problems remains an open question. Moreover, for plasma physics, many problems are nonlinear, whereas quantum computers are designed to carry out unitary evolution in Hilbert spaces, which are fundamentally linear. In this seminar, I will present the first results using real quantum hardware to simulate a toy problem that is relevant to laser-plasma interactions. A generally applicable algorithm is derived, which encode three-wave interactions on quantum hardware efficiently. The algorithm is implemented using two compilation approaches. First, each simulation step is compiled as a sequence of standard gates. Using this approach, ~10 simulation steps can be carried out before results are corrupted by decoherence.  Second, each simulation step is compiled as a single customized gate, which is realized using optimal control. Using this approach, the simulation depth is extended to ~100. Our results highlight the advantage of using customized gates on noisy intermediate-scale quantum computers. The generalized nonlinear gates are potentially useful building blocks for solving a large class of problems in plasma/fluid dynamics, nonlinear optics, and lattice gauge theories on quantum computers.

Bio: Dr. Yuan Shi is a Lawrence Postdoctoral Fellow in the Physics Division at Lawrence Livermore National Laboratory (LLNL). His current research topics include laser-plasma interactions, theoretical physics, and scientific computing. In a recent work, Dr. Shi and team demonstrated a first-of-the-kind example using actual quantum computing hardware to solve a problem relevant for plasma physics. Prior to LLNL, Dr. Shi earned his MA (2014) and PhD (2018) in Astrophysical Sciences, Program in Plasma Physics, from Princeton University, where he was a recipient of the Carl Oberman Fellowship. His PhD work was awarded the Marshall Rosenbluth Outstanding Doctoral Thesis Award by the American Physical Society, for elegantly describing three-wave coupling in oblique magnetic fields, and for adapting quantum field theory to describe plasma physics in strong-field regimes. Yuan has a BSc from the University of Hong Kong and was a recipient of the Rosita King Ho Scholarship.