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

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 $97\%$.