Chaotic oscillation and random-number generation based on nanoscale optical-energy transfer

TL;DR

This paper demonstrates theoretically and numerically that nanoscale quantum dot systems can exhibit chaotic oscillations and generate random numbers, with potential applications in ultrasmall random-number generators.

Contribution

It introduces a nanoscale optical system with energy transfer dynamics that can produce chaos and randomness, advancing the understanding of complex behaviors in nanodevices.

Findings

Chaotic oscillations occur in nanoscale quantum dot systems with time delays.

The system's signals pass statistical tests for randomness.

Nanoscale optical energy transfer can be used for ultrasmall RNGs.

Abstract

By using nanoscale energy-transfer dynamics and density matrix formalism, we demonstrate theoretically and numerically that chaotic oscillation and random-number generation occur in a nanoscale system. The physical system consists of a pair of quantum dots (QDs), with one QD smaller than the other, between which energy transfers via optical near-field interactions. When the system is pumped by continuous-wave radiation and incorporates a timing delay between two energy transfers within the system, it emits optical pulses. We refer to such QD pairs as nano-optical pulsers (NOPs). Irradiating an NOP with external periodic optical pulses causes the oscillating frequency of the NOP to synchronize with the external stimulus. We find that chaotic oscillation occurs in the NOP population when they are connected by an external time delay. Moreover, by evaluating the time-domain signals by statistical-test suites, we confirm that the signals are sufficiently random to qualify the system as a random-number generator (RNG). This study reveals that even relatively simple nanodevices that interact locally with each other through optical energy transfer at scales far below the wavelength of irradiating light can exhibit complex oscillatory dynamics. These findings are significant for applications such as ultrasmall RNGs.