Ultrafast cryptography with indefinitely switchable optical nanoantennas

TL;DR

This paper introduces indefinite switching in optical nanoantennas, enabling high-speed, secure cryptographic operations with a single bistable element, surpassing traditional binary switching paradigms.

Contribution

It reveals the phenomenon of indefinite switching in bistable systems and demonstrates its application in ultrafast, secure optical cryptography using nanoantennas.

Findings

Achieved cryptographic decoding at 0.1 to 1 terabits per second.

Demonstrated secure stream deciphering of the word 'enigma'.

Showed that indefinite switching enhances security and speed in optical systems.

Abstract

Bistability is widely exploited to demonstrate all-optical signal processing and light-based computing. The standard paradigm of switching between two steady states corresponding to '0" and '1" bits is based on the rule that a transition occurs when the signal pulse intensity overcomes the bistability threshold, and otherwise, the system remains in the initial state. Here, we break with this concept by revealing the phenomenon of indefinite switching in which the eventual steady state of a resonant bistable system is transformed into a nontrivial function of signal pulse parameters for moderately intense signal pulses. The essential nonlinearity of the indefinite switching allows realization of well-protected cryptographic algorithms with a single bistable element in contrast to software-assisted cryptographic protocols that require thousands of logic gates. As a proof of concept, we demonstrate stream deciphering of the word 'enigma' by means of an indefinitely switchable optical nanoantenna. An extremely high bitrate ranging from ~0.1 to 1 terabits per second and a small size make such systems promising as basic elements for all-optical cryptographic architectures.