Critical behavior of the Ising model by preparing the thermal state on a quantum computer
Xiaoyang Wang, Xu Feng, Tobias Hartung, Karl Jansen, Paolo Stornati
Abstract
We simulate the critical behavior of the Ising model utilizing a thermal state prepared using quantum computing techniques. The preparation of the thermal state is based on the variational quantum imaginary time evolution (QITE) algorithm. The initial state of QITE is prepared as a classical product state, and we propose a systematic method to design the variational ansatz for QITE. We calculate the specific heat and susceptibility of the long-range interacting Ising model and observe indications of the Ising criticality on a small lattice size. We find the results derived by the quantum algorithm are well consistent with the ones from exact diagonalization, in both the neighborhood of the critical temperature and the low-temperature region.