Rapid developments of quantum information technology show promising opportunities for simulating quantum field theory in near-term quantum devices. In this work, we formulate the theory of (time-dependent) variational quantum simulation of the 1+1 dimensional $\lambda \phi^4$ quantum field theory including encoding, state preparation, and time evolution, with several numerical simulation results. These algorithms could be understood as near-term variational analogs of the Jordan-Lee-Preskill algorithm, the basic algorithm for simulating quantum field theory using universal quantum devices. Besides, we highlight the advantages of encoding with harmonic oscillator basis based on the LSZ reduction formula and several computational efficiency such as when implementing a bosonic version of the unitary coupled cluster ansatz to prepare initial states. We also discuss how to circumvent the "spectral crowding" problem in the quantum field theory simulation and appraise our algorithm by both state and subspace fidelities.

翻译：量子信息技术的快速发展展示了在近期量子装置中模拟量子场理论的极好机会。 在这项工作中,我们制定了1+1维的量子场理论的(时间依赖)变异量模拟理论,包括编码、状态准备和时间演进,并附有数位模拟结果。这些算法可以被理解为约旦-利普基算法的近期变异类,即使用通用量子装置模拟量子场理论的基本算法。此外,我们强调基于LSZ削减公式和若干计算效率(例如实施单元组合组合组合组合组合体亚萨茨的博索尼格版本以准备初始状态)的调相调和振荡器的编码的优点。我们还讨论如何绕过量子场理论模拟中的“光谱挤”问题,并以国家和次空间的忠贞度来评估我们的算法。