Ptychographic estimation of qudit states encoded in the angular position and orbital angular momentum of single photons

Fuente: arXiv
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Main Authors: da Costa, A. M., Neves, L.
Format: Preprint
Published: 2025
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author da Costa, A. M.
Neves, L.
author_facet da Costa, A. M.
Neves, L.
contents Ptychography is a computational imaging technique mainly used in optical and electron microscopy. Its quantum analogue was recently introduced as a simple method for estimating unknown pure quantum states through projections onto partially overlapping subspaces, each one followed by a projective measurement in the Fourier basis. In the end, an iterative algorithm estimates the state from the collected data. Here, we theoretically describe how to implement this method for $D$-dimensional qudit states encoded in the angular position and orbital angular momentum (OAM) of single photons. For this purpose, we define the qudit by discretizing the spatial profile of a photon in cylindrical coordinates, using an array of $D$ angular slits symmetrically distributed in the transverse plane. To apply ptychography to this encoding, we show that the intermediate projections will be carried out by simple binary spatial filters in the angular paths, while the measurement in the Fourier basis will be performed by postselecting $D$ OAM modes compatible with the quantum Fourier transform of the path basis. We illustrate the effectiveness of this scheme through simulations and discuss its experimental feasibility.
format Preprint
id arxiv_https___arxiv_org_abs_2504_14073
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ptychographic estimation of qudit states encoded in the angular position and orbital angular momentum of single photons
da Costa, A. M.
Neves, L.
Quantum Physics
Ptychography is a computational imaging technique mainly used in optical and electron microscopy. Its quantum analogue was recently introduced as a simple method for estimating unknown pure quantum states through projections onto partially overlapping subspaces, each one followed by a projective measurement in the Fourier basis. In the end, an iterative algorithm estimates the state from the collected data. Here, we theoretically describe how to implement this method for $D$-dimensional qudit states encoded in the angular position and orbital angular momentum (OAM) of single photons. For this purpose, we define the qudit by discretizing the spatial profile of a photon in cylindrical coordinates, using an array of $D$ angular slits symmetrically distributed in the transverse plane. To apply ptychography to this encoding, we show that the intermediate projections will be carried out by simple binary spatial filters in the angular paths, while the measurement in the Fourier basis will be performed by postselecting $D$ OAM modes compatible with the quantum Fourier transform of the path basis. We illustrate the effectiveness of this scheme through simulations and discuss its experimental feasibility.
title Ptychographic estimation of qudit states encoded in the angular position and orbital angular momentum of single photons
topic Quantum Physics
url https://arxiv.org/abs/2504.14073