arXiv subjects

Takuma Noto

Publications and source records attributed to Takuma Noto.

2 recordsLinked to original sources

arXiv2022

Estimation of the number of logical qubits required for radiation transport calculations with a quantum computer

As an application of fault-tolerant quantum computers, we consider radiation transport calculations in this study. Radiation transport calculation using Monte Carlo calculation can obtain a solution to even a problem difficult to solve analytically. However, it is time-consuming depending on the scale and precision of the problem. Because it is known that the computational complexity of Monte Carlo calculation can be square rooted by quantum amplitude estimation, acceleration can be expected if radiation transport calculation is run on a quantum computer. In this study, we designed and investigated a quantum circuit for a simplified transport calculation in which the reaction is only forward scattering or absorption and the energy and time do not change as well as showed the possibility of acceleration the calculation. Further, we estimated the number of logical qubits required to solve practical problems based on the quantum circuit.

quant-ph↗

arXiv2020

Quantum circuit to estimate pi using quantum amplitude estimation

This study presents a quantum circuit for estimating the pi value using arithmetic circuits and by quantum amplitude estimation. We review two types of quantum multipliers and propose quantum squaring circuits based on the multiplier as basic arithmetic circuits required for performing quantum computations. The squarer realized by a quantum adder with the gate size of $ O(n) $ requires $ O(n^2) $ gates and at least one ancillary qubits, while that realized by using quantum Fourier transform (QFT) requires $ O(n^3) $ gates without ancillary qubit. The proposed quantum circuit to estimate pi is based on the Monte Carlo method, quantum amplitude estimation, and quantum squarer. By applying the quantum squarer using QFT, the circuit was implemented in $ 4n + 1 $ qubits at $ 2^{2n} $ sampling. The proposed method was demonstrated using a quantum computer simulator with $ n $ being varied from 2 to 6, and the obtained result was compared with the one obtained by performing a classical calculation.

quant-ph↗