The Mitsubishi Chemical Group (hereafter, "Mitsubishi Chemical"), Keio University (headquartered in Minato, Tokyo, President Kohei Itoh) and IBM Japan, Ltd. (hereafter, "IBM", headquartered in Minato, Tokyo, General Manager Akio Yamaguchi), are pleased to announce the publication of a paper describing the research results of a new computational method for a large-scale and high-accuracy quantum chemistry calculation on quantum computers, a joint project from IBM Quantum Network Hub at Keio University Quantum Computing Center, in npj Quantum Information,a world-renowned Nature Research Journal.
Mitsubishi Chemical, Keio University and IBM Japan developed approaches to accurately calculate quantum mechanical ground states of large chemical systems, and the approaches are called HTN+QMC method and pseudo-Hadamard test technique; HTN+QMC combines a partitioning method called Hybrid Tensor Network (HTN), with a high-accuracy calculation method called Quantum Monte Carlo (QMC), to calculate the energy of large molecules and solids. The pseudo-Hadamard test technique efficiently calculates the overlap between quantum states from quantum circuits. By applying these methods to quantum chemistry calculations for photochromic model molecules on the gate-based quantum computer IBM Quantum System One, ground state energies were successfully computed as 0.042 ± 2.0 milli-Hartree, an accuracy comparable to that of a noiseless simulator.
This research is expected to pave the way for accurate analysis of the physical properties of large-scale molecules and solids, which are beyond the size that can be handled by a stand-alone quantum computer.
We plan to continue research in the area of using quantum computers to accelerate the development of a wide range of new materials.
