Zhu D, Johri S, Linke N M, Landsman K A, Huerta Alderete C, Nguyen N H, Matsuura A Y, Hsieh T H, Monroe C
Joint Quantum Institute, University of Maryland, College Park, MD 20742.
Department of Physics, University of Maryland, College Park, MD 20742.
Proc Natl Acad Sci U S A. 2020 Oct 13;117(41):25402-25406. doi: 10.1073/pnas.2006337117. Epub 2020 Sep 28.
Finite-temperature phases of many-body quantum systems are fundamental to phenomena ranging from condensed-matter physics to cosmology, yet they are generally difficult to simulate. Using an ion trap quantum computer and protocols motivated by the quantum approximate optimization algorithm (QAOA), we generate nontrivial thermal quantum states of the transverse-field Ising model (TFIM) by preparing thermofield double states at a variety of temperatures. We also prepare the critical state of the TFIM at zero temperature using quantum-classical hybrid optimization. The entanglement structure of thermofield double and critical states plays a key role in the study of black holes, and our work simulates such nontrivial structures on a quantum computer. Moreover, we find that the variational quantum circuits exhibit noise thresholds above which the lowest-depth QAOA circuits provide the best results.
多体量子系统的有限温度相对于从凝聚态物理到宇宙学的各种现象至关重要，但通常难以模拟。我们使用离子阱量子计算机以及受量子近似优化算法（QAOA）启发的协议，通过在各种温度下制备热场双重态，生成了横向场伊辛模型（TFIM）的非平凡热量子态。我们还利用量子 - 经典混合优化在零温度下制备了TFIM的临界态。热场双重态和临界态的纠缠结构在黑洞研究中起着关键作用，我们的工作在量子计算机上模拟了这种非平凡结构。此外，我们发现变分量子电路表现出噪声阈值，高于该阈值时，最低深度的QAOA电路能提供最佳结果。
