Quantum-Classical Variational Approaches with Single-Qubit Operation on Near-Term Quantum Processors
Tsukasa Miki, Daisuke Tsukayama, Ryo Okita, M Shimada, Jun‐ichi Shirakashi · 2022 IEEE 22nd International Conference on Nanotechnology (NANO) · 2022
Currently developed quantum devices have the potential to show a computational advantage if quantum applications exploit the devices efficiently. Variational quantum algorithms (VQAs) combine a quantum processor with a classical computer to minimize the expectation value of a problem Hamiltonian. An important element of VQAs is the state-preparation circuit, referred to as variational quantum circuit. To improve the ability for solving combinatorial optimizations with VQAs, we show that the variational quantum circuit with single-qubit gates only can find the ground state more quickly. We demonstrate our VQA by using real quantum processors through IBM Quantum. As a result, the variational circuit with single-qubit gates takes four times smaller numbers of function evaluations than that with entangling gates, such as controlled-X gates.