论文标题
将变量量子本质量扩展到有限温度
Extending the Variational Quantum Eigensolver to Finite Temperatures
论文作者
论文摘要
我们提出了一个称为量子-VQT（QVQT）的变分量子热剂（VQT），该变量将变异量子eigensolver（VQE）扩展到有限的温度。 QVQT利用两个变异电路之间的中间测量来编码量子设备上的密度矩阵。经典优化提供了热状态，同时也提供了量子机械系统的所有相关激发态。我们证明了两个不同的自旋系统的QVQT的功能。首先，我们分析了QVQT作为电路深度的函数和一维海森堡链的温度的函数。其次，我们使用激发态来绘制二维J1-J2海森伯格模型的完整，依赖温度的相图。数值实验证明了我们的方法的效率，可以很容易地将其应用于当前可用的NISQ设备上有限温度下的各种量子多体系统。
We present a variational quantum thermalizer (VQT), called quantum-VQT (qVQT), which extends the variational quantum eigensolver (VQE) to finite temperatures. The qVQT makes use of an intermediate measurement between two variational circuits to encode a density matrix on a quantum device. A classical optimization provides the thermal state and, simultaneously, all associated excited states of a quantum mechanical system. We demonstrate the capabilities of the qVQT for two different spin systems. First, we analyze the performance of qVQT as a function of the circuit depth and the temperature for a 1-dimensional Heisenberg chain. Second, we use the excited states to map the complete, temperature dependent phase diagram of a 2-dimensional J1-J2 Heisenberg model. The numerical experiments demonstrate the efficiency of our approach, which can be readily applied to study various quantum many-body systems at finite temperatures on currently available NISQ devices.
