Femtosecond Photo-Induced Multiphoton Analog Computation for Symmetry-Based Pattern Classification

TL;DR

This paper demonstrates a femtosecond multiphoton coherent control method for analog computation, enabling efficient classification of sequences based on their symmetry properties using atomic sodium's nonlinear response.

Contribution

It introduces a novel femtosecond photo-induced multiphoton computation scheme that classifies sequences with constant complexity, leveraging multiphoton absorption in sodium atoms.

Findings

Sequence classification achieved with two observables.

Constant number of operations regardless of sequence length.

Potential for future 'smart hardware' applications.

Abstract

Multiphoton femtosecond coherent control of is used for implementing innovative photo-induced analog coherent computation that generally might be a basis for future "smart hardware". The specific implemented computational task the classification of an unknown sequence into one of the three groups: (i) a constant sequence that is composed of identical numbers, (ii) a sequence that is antisymmetric around a given point, or (iii) neither. The input sequence is encoded into the spectral phases of a broadband femtosecond pulse and the computational task is being carried out by the multiphoton nonlinear response of the irradiated physical system. Here, it is the simultaneous coherent two- and three-photon absorption in atomic sodium (Na). The corresponding computational resources are the manifold of initial-to-final multiphoton excitation pathways photo-induced by the broad spectrum of the irradiating femtosecond pulse. The answer is obtained by measuring only two observables, which are two state-populations excited via the two- and three-photon absorption processes. Hence, the computational task is accomplished in a constant number of operations irrespective of the sequence length. As such, the presented scheme, where the femtosecond pulse serves as a query and the irradiated physical system serves as an oracle, provides a sufficient gain in the computational complexity.