Indefinite-mean Pareto photon distribution from amplified quantum noise

TL;DR

This paper demonstrates the first experimental evidence of indefinite-mean Pareto photon distributions generated from amplified quantum noise in nonlinear optical processes, with controllable heavy-tail properties.

Contribution

It introduces the observation of indefinite-mean Pareto photon distributions in quantum optics and shows how to control the Pareto exponent through experimental parameters.

Findings

Observed Pareto distribution with exponent 1.31 in supercontinuum generation

Controlled Pareto exponents by adjusting experimental parameters

Demonstrated non-equilibrium state production via single-photon subtraction

Abstract

Extreme events appear in many physics phenomena, whenever the probability distribution has a ''heavy tail'', differing very much from the equilibrium one. Most unusual are the cases of power-law (Pareto) probability distributions. Among their many manifestations in physics, from ''rogue waves'' in the ocean to L\'evy flights in random walks, Pareto dependences can follow very different power laws. For some outstanding cases the power exponents are less than 2, leading to indefinite mean values, let alone higher moments. Here we present the first evidence of indefinite-mean Pareto distribution of photon numbers at the output of nonlinear effects pumped by parametrically amplified vacuum noise, known as bright squeezed vacuum (BSV). We observe a Pareto distribution with power exponent 1.31 when BSV is used as a pump for supercontinuum generation, and other heavy-tailed distributions (however with definite moments) when it pumps optical harmonics generation. Unlike in other fields, we can flexibly control the Pareto exponent by changing the experimental parameters. This extremely fluctuating light is interesting for ghost imaging and quantum thermodynamics as a resource to produce more efficiently non-equilibrium states by single-photon subtraction, the latter we demonstrate experimentally.