Calculation of a capacitively-coupled floating gate array toward quantum annealing machine

Quantum annealing machines based on superconducting qubits, which have the potential to solve optimization problems faster than digital computers, are of great interest not only to researchers but also to the general public. In this paper, we propose a quantum annealing machine based on a semiconductor floating gate (FG) array. The purpose of using the architecture of nand flash memories is to reuse a mature technology to create large arrays of silicon qubits. Current high-density nand flash memories use sufficiently small FG cells to make the number of electrons stored in each cell small and countable. The high packing density of these cells creates mutual capacitive couplings that can be used to generate cell-to-cell interactions. We explore these characteristics to derive an Ising Hamiltonian for the FG system in the single-electron regime. Considering the size of a cell (10 nm), the ideal operation temperature of a quantum annealer based on FG cells is estimated to be approximately that of liquid nitr...