Correlated two-photon scattering in a one-dimensional waveguide coupled to two- or three-level giant atoms

TL;DR

This paper investigates two-photon scattering in a one-dimensional waveguide coupled to giant atoms, deriving exact wavefunctions and analyzing how phase shifts influence photon-photon correlations, with potential applications in quantum information processing.

Contribution

It provides exact analytical solutions for two-photon scattering in giant atom systems and explores how phase shifts can enhance photon-photon correlations.

Findings

Phase shift can improve photon-photon correlation in two-level giant atoms.

Photon-photon correlation is significantly increased in three-level giant atom systems.

Tuning phase shifts enhances photon interactions and correlation distances.

Abstract

We study the two-photon scattering processes in a one-dimensional waveguide coupled to a two- or three-level giant atom, respectively. The accumulated phase shift between the two coupling points can be utilized to alter the scattering processes. We obtain the exact interacting two-photon scattering wavefunction of these two systems following the Lippmann-Schwinger formalism, from which the analytical expressions of incoherent power spectra and second-order correlations are also derived. The incoherent spectrum, defined by the correlation of the bound state, serves as a useful indication of photon-photon correlation. The second-order correlation function gives a direct measure of photon-photon correlation. For photons scattered by the two-level giant atom, the accumulated phase shift can be used to improve photon-photon correlation,and adjust the evolution of the second-order correlation. In the system of the three-level giant atom, the photon-photon correlation can be substantially increased. Moreover, the photon-photon interactions and correlation distance of scattered photons can be further enhanced by tuning the accumulated phase shift.