Classical Simulation of an All-Optical Toffoli Gate using Soliton Scattering through Asymmetric Potential Wells

TL;DR

This paper demonstrates a numerically simulated all-optical Toffoli gate using soliton scattering by asymmetric potential wells, showing broader operational parameters and robustness in nonlinear optical systems.

Contribution

It introduces a novel scheme for implementing a Toffoli gate with solitons and asymmetric potential wells, expanding the potential for classical optical quantum gate analogs.

Findings

Asymmetry broadens operational parameter window.

Weak inter-component coupling is not essential.

Varying asymmetry affects gate performance.

Abstract

We propose and numerically simulate an all-optical Toffoli (controlled-controlled-NOT) gate based on the scattering of spatial solitons by asymmetric P\"oschl-Teller potential wells. In our scheme, the logical state of the target bit is encoded in the relative spatial ordering of two distinguishable soliton components, while the control bits are represented by the presence or absence of external potential wells. We solve the nonlinear Schr\"odinger equations governing the soliton dynamics and systematically scan soliton amplitude and velocity, analyzing reflection and transmission coefficients to identify the operational conditions for Toffoli gate behavior. Our results demonstrate that introducing asymmetry in the potential wells significantly broadens the operational parameter window compared to symmetric configurations. We also investigate the impacts of varying degrees of asymmetry and soliton amplitude on gate performance. Furthermore, we examine the influence of weak inter-component coupling and confirm that it is not essential for gate operation. These findings generalize earlier soliton-based CNOT simulations and support the broader feasibility of classical analog modeling of multi-qubit logic gates in nonlinear optical systems.