Variational Quantum Eigensolver with Fewer Qubits

Understand

We propose a qubit efficient scheme to study ground state properties of quantum many-body systems on near-term noisy intermediate scale quantum computers.

• One can obtain a tensor network representation of the ground state using a number of qubits smaller than the physical degrees of freedom.
• By increasing the qubits number, one can exponentially increase the bond dimension of the tensor network variational ansatz on a quantum computer.
• Moreover, we construct circuits blocks which respect U(1) and SU(2) symmetries of the physical system and show that they can significantly speed up the training process and alleviate the gradient vanishing problem.