Japan Geoscience Union Meeting 2025

Presentation information

[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS08] Processes of the Moist Atmosphere Across Scales

Wed. May 28, 2025 9:00 AM - 10:30 AM Exhibition Hall Special Setting (6) (Exhibition Hall 7&8, Makuhari Messe)

convener:Hiroaki Miura(The University of Tokyo), Daisuke Takasuka(Graduate School of Science, Tohoku University), Atsushi Hamada(University of Toyama), Satoru Yokoi(Japan Agency for Marine-Earth Science and Technology), Chairperson:Satoru Yokoi(Japan Agency for Marine-Earth Science and Technology), Hiroaki Miura(The University of Tokyo)

9:15 AM - 9:30 AM

[AAS08-02] Application of Quantum Computing for Collision-Coalescence Process of Cloud Droplets

★Invited Papers

*Kazumasa Ueno1, Hiroaki Miura1 (1.The University of Tokyo)

Keywords:Quantum Computing, Cloud Collision-Coalescence Process, Master Equation, Stochastic Process

Quantum computers are based on quantum mechanics and are expected to enable vast computations that are infeasible for classical computers. A key aspect of quantum computing is the efficient utilization of quantum properties such as superposition, interference, and entanglement. However, to effectively use quantum computers, it is necessary to address challenges related to linearity and readout. One promising approach to overcoming the linearity issue is solving the time evolution of a distribution function. This approach is viable because, even if the target process itself is nonlinear, its distribution evolution can be described linearly. Furthermore, the quantities of interest in computation are not the distribution itself, but rather statistical measures such as expectations and variances in many cases. Since only a small number of variables need to be read out to extract useful information, this approach also provides an efficient way to address the readout problem.

In this study, we propose a quantum algorithm for solving the master equation that describes the evolution of the cloud droplet collision-coalescence process. When considering a large variety of cloud droplets, the number of possible states becomes enormous and direct solutions of the master equation are computationally infeasible. Alfonso et al. (2015) managed to make computations feasible by leveraging the fact that only a limited number of states are realized in practice, but their approach was restricted to a maximum of 40 cloud droplet types. In this work, we develop a quantum algorithm, implement it on the Qiskit Aer simulator, and estimate its computational cost. Our results show that quantum computation provides outcomes equivalent to those obtained through direct classical computation. Additionally, while the computational cost of classical methods increases exponentially with the number of cloud droplet types, the quantum computation exhibits only a quadratic growth. These results highlight the potential of quantum computing for computing distribution functions in atmospheric science, demonstrating a promising application in the field.