  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, both in the
neighbourhood of the critical temperature and the low-temperature region.

Quantum Physics;Statistical Mechanics;High Energy Physics - Lattice