Kokail Christian, Sundar Bhuvanesh, Zache Torsten V, Elben Andreas, Vermersch Benoît, Dalmonte Marcello, van Bijnen Rick, Zoller Peter
Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, Innsbruck A-6020, Austria.
Center for Quantum Physics, University of Innsbruck, Innsbruck A-6020, Austria.
Phys Rev Lett. 2021 Oct 22;127(17):170501. doi: 10.1103/PhysRevLett.127.170501.
Learning the structure of the entanglement Hamiltonian (EH) is central to characterizing quantum many-body states in analog quantum simulation. We describe a protocol where spatial deformations of the many-body Hamiltonian, physically realized on the quantum device, serve as an efficient variational ansatz for a local EH. Optimal variational parameters are determined in a feedback loop, involving quench dynamics with the deformed Hamiltonian as a quantum processing step, and classical optimization. We simulate the protocol for the ground state of Fermi-Hubbard models in quasi-1D geometries, finding excellent agreement of the EH with Bisognano-Wichmann predictions. Subsequent on-device spectroscopy enables a direct measurement of the entanglement spectrum, which we illustrate for a Fermi Hubbard model in a topological phase.
学习纠缠哈密顿量（EH）的结构是在模拟量子模拟中表征量子多体态的核心。我们描述了一种协议，其中在量子设备上物理实现的多体哈密顿量的空间变形，用作局部EH的有效变分近似。最优变分参数在一个反馈回路中确定，该回路涉及以变形哈密顿量作为量子处理步骤的猝灭动力学和经典优化。我们在准一维几何结构中模拟了费米 - 哈伯德模型基态的协议，发现EH与比索尼亚诺 - 威奇曼预测结果高度吻合。随后的设备上光谱学能够直接测量纠缠谱，我们以处于拓扑相的费米 - 哈伯德模型为例进行说明。
