SOLVING THE GROUND STATE OF QUANTUM RABI MODEL WITH VARIATIONAL QUANTUM EIGENSOLVER

In the study of solving the ground state of quantum systems by variational principle, variational quantum algorithm is widely adopted to solve the ground state. As one kind of quantum classical hybrid algorithm, variational quantum eigensolver plays an important role. In this paper, we calculate ground state of quantum Rabi model in the ultra-strong coupling regime by invoking the variational quantum eigensolver in the open-source quantum computing simulator Qiskit. In the 3-qubit computing basis, we use the standard binary encoding method to encode the operators and quantum states in the quantum Rabi model, and measure the minimum average value (ground state energy) on the quantum circuit constructed by the Hamiltonian variational ansatz. Finally, comparing the calculation results of the variational quantum eigensolver with the exact values obtained by classical numerical simulations, we discuss the dependence of computational accuracy of the variational quantum eigensolver on the consumption of the number of the qubits and the coupling strength in quantum Rabi model.