Characterizing $d-$dimensional quantum channels by means of quantum process tomography

TL;DR

This paper introduces an optical setup using programmable spatial light modulators for quantum process tomography of high-dimensional photonic systems, successfully reconstructing various quantum channels with high fidelity.

Contribution

It presents a simple optical architecture for quantum process tomography in high-dimensional systems, capable of characterizing typical noise processes and atmospheric turbulence effects.

Findings

Successfully reconstructed amplitude, phase, and depolarizing channels in dimension 5.

Reconstructed atmospheric turbulence effects in dimension 4.

Achieved fidelities above 97% between experimental and expected states.

Abstract

In this work we propose a simple optical architecture, based on phase-only programmable spatial light modulators, in order to characterize general processes on photonic spatial quantum systems in a $d>2$ Hilbert space. We demonstrate the full reconstruction of typical noises affecting quantum computing, as amplitude shifts, phase shifts, and depolarizing channel in dimension $d=5$. We have also reconstructed simulated atmospheric turbulences affecting a free-space transmission of qudits in dimension $d=4$. In each case, quantum process tomography (QPT) was performed in order to obtain the matrix $\chi$ that fully describe the corresponding quantum channel, $\mathcal{E}$. Fidelities between the states experimentally obtained after go through the channel and the expected ones are above $97\%$.