Implementation and characterization of a controllable dephasing channel based on coupling polarization and spatial degrees of freedom of light

TL;DR

This paper experimentally demonstrates a controllable dephasing quantum channel using photonic polarization and spatial degrees of freedom, revealing oscillatory state evolution and enabling detailed process characterization.

Contribution

It introduces a novel controllable dephasing channel based on coupling polarization and spatial modes, with unique oscillatory behavior and comprehensive process tomography.

Findings

The channel exhibits oscillatory pure-to-mixed state evolution.

Quantum process tomography successfully characterizes the channel.

The method enables visualization of dephasing effects in quantum systems.

Abstract

We present the experimental implementation and theoretical model of a controllable dephasing quantum channel using photonic systems. The channel is implemented by coupling the polarization and the spatial distribution of light, that play, in the perspective of Open Quantum Systems, the role of quantum system and environment, respectively. The capability of controlling our channel allows us to visualize its effects in a quantum system. Differently from standard dephasing channels, our channel presents an exotic behavior in the sense that the evolution of a state, from a pure to a mixed state, shows an oscillatory behavior if tracked in the Bloch sphere. Additionally, we report the evolution of the purity and perform a quantum process tomography to obtain the \chi matrix associated to our channel.