Bose-Hubbard model with a single qubit

The use of a single-qubit parametrized circuit as an Ansatz for the variational wave function in the calculation of the ground state energy of a quantum many-body system is demonstrated using the one-dimensional Bose-Hubbard model. Comparison is made to calculations where a classic neural network is used to generate the variational wave function. Computations carried out on IBM Quantum hardware are also presented.