Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optics Letters

Entangled two-photon states in the helical Mathieu-Gauss modes basis

Daniel Salamanca-Roldán, A. A. Aguilar-Cardoso, O. A. Ramírez-Espinosa, Tonatiuh Moctezuma-Quistian, Pablo Yepiz-Graciano, Carmelo Rosales‐Guzmán, Roberto Ramírez-Alarcón

Published Nov 20, 2025• 2 citations
Publisher

Abstract

In this work, we provide a complete theoretical and experimental study of a two-photon quantum state entangled in the orbital angular momentum (OAM) degree of freedom of the helical Mathieu-Gauss (HMG) modes. The state is generated by a type II spontaneous parametric down conversion (SPDC) process. Our analysis shows that the generated state is composed by the superposition of two symmetric Bell states with tunable contributions determined by the eccentricity parameter of the HMG modes. The predicted entangled state is confirmed experimentally by measuring the HMG modal joint probability of the SPDC two-photon state and the violation of Bell-type inequalities.

DOI
10.1364/ol.579046

Related papers

Tuning the probability detection of orbital-angular-momentum-entangled photons in helical Ince-Gauss modes

Aarón A. Aguilar-Cardoso, Daniel Rodriguez-Guillen, Roberto Ramírez-Alarcón

In this paper we provide a detailed theoretical and experimental analysis of the two-photon orbital-angular-momentum-entangled state, generated by a type-I spontaneous parametric down conversion (SPDC) process, when decomposed in terms of the helical Ince-Gauss (HIG) mode basis. By exploiting the unique characteristics of this modal basis we show how the probability detection of the photon pair can be tuned with the ellipticity parameter of the modes. We also show that on the HIG basis the SPDC state has the contribution of two different symmetric Bell states, and it is possible to maximize the probability of each HIG symmetric Bell state separately also by tuning the elipticity of the projected basis. The observed properties are confirmed experimentally by implementing measurements of the HIG modal joint probability of the SPDC two-photon state and Bell-type inequality violation experiments.

arXiv:2507.07035•Physical Review A•Feb 13, 2024•2 citations

Mathieu–Gauss photons: non-diffraction and self-healing at the quantum regime

Daniel Salamanca-Roldán, Oscar Alejandro Ramírez-Espinosa, Roberto Ramírez-Alarcón +3 more

Abstract Quantum entanglement represents one of the most fascinating aspects of quantum mechanics and underpins the advancement of next-generation quantum-based technologies. Of particular interest is quantum entanglement in the spatial degree of freedom of light. As such, in this paper, we analyze a two-photon orbital angular momentum entangled state, decomposed in terms of helical Mathieu–Gauss ( HMG ) modes and generated through a type II spontaneous parametric down conversion process. Furthermore, a spatially-resolved heralded single photon detection system allowed the observation of the transverse spatial distribution of correlated HMG photons and the corroboration of their self-healing and non-diffractive properties. More precisely, we were able to corroborate that HMG photons maintain the same non-diffractive properties of classical HMG beams and that their time-averaged transverse field distribution reconstructs itself upon propagation in the presence of an opaque obstacle.

Journal of Optics•Jan 1, 2026•0 citations

Tailoring quantum entanglement of orbital angular momentum

Melanie G. McLaren

ENGLISH ABSTRACT: High-dimensional quantum entanglement offers an increase in information capacity per photon; a highly desirable property for quantum information processes such as quantum communication, computation and teleportation. As the orbital angular momentum (OAM) modes of light span an infinite-dimensional Hilbert space, they have become frontrunners in achieving entanglement in higher dimensions. In light of this, we investigate the potential of OAM entanglement of photons by controlling the parameters in both the generation and measurement systems. We show the experimental procedures and apparatus involved in generating and measuring entangled photons in two-dimensions. We verify important quantum tests such as the Einstein, Podolsky and Rosen (EPR) paradox using OAM and angle correlations, as well as a violation of a Bell-type inequality. By performing a full state tomography, we characterise our quantum state and show we have a pure, highly entangled quantum state. We demonstrate that this method can be extended to higher dimensions. The experimental techniques used to generate and measure OAM entanglement place an upper bound on the number of accessible OAM modes. As such, we investigate new methods in which to increase the spiral bandwidth of our generated quantum state. We alter the shape of the pump beam in spontaneous parametric down-conversion and demonstrate an effect on both OAM and angle correlations. We also made changes to the measurement scheme by projecting the photon pairs into the Bessel-Gaussian (BG) basis and demonstrate entanglement in this basis. We show that this method allows the measured spiral bandwidth to be optimised by simply varying the continuous radial parameter of the BG modes. We demonstrate that BG modes can be entangled in higher dimensions compared with the commonly used helical modes by calculating and comparing the linear entropy and fidelity for both modes. We also show that quantum entanglement can be accurately simulated using classical light using back-projection, which allows the study of projective measurements and predicts the strength of the coincidence correlations in an entanglement experiment. Finally, we make use of each of the techniques to demonstrate the effect of a perturbation on OAM entanglement measured in the BG basis. We investigate the self-healing property of BG beams and show that the classical property is translated to the quantum regime. By calculating the concurrence, we see that measured entanglement recovers after encountering an obstruction.

•Dec 1, 2014•0 citations

Increasing the orbital angular momentum bandwidth of entangled photons

Jacquiline Romero, Daniel Giovannini, Sonja Franke‐Arnold +2 more

The bandwidth of any communication system, classical or quantum, is limited by the number of orthogonal states in which the information can be encoded. Quantum key distribution systems available commercially rely on the two-dimensional polarisation state of photons. Quantum computation has also been largely designed on the basis of qubits. However, a photon is endowed with other degrees of freedom, such as orbital angular momentum (OAM). OAM is an attractive basis to be used for quantum information because it is discrete and theoretically infinite-dimensional. This promises a higher information capacity per photon which can lead to more complex quantum computation protocols and more security and robustness for quantum cryptography. Entanglement of OAM naturally arises from spontaneous parametric down-conversion (SPDC). However, any practical experiment utilising the innately high-dimensional entanglement of the orbital angular momentum (OAM) state space of photons is subject to the modal capacity of the detection system. Only a finite subset of this space is accessible experimentally. Given such a constraint, we show that the number of measured, entangled OAM modes in photon pairs generated by SPDC can be increased by tuning the phase-matching conditions in the SPDC process. We achieve this by tuning the orientation angle of the nonlinear crystal generating the entangled photons.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Nov 19, 2012•0 citations

Extrinsic orbital angular momentum of entangled photon-pairs in spontaneous parametric down-conversion

Sheng Feng, Prem Kumar

Starting from the standard Hamiltonian describing the optical non-linear process of spontaneous parametric down-conversion, we theoretically show that the generated entangled photon-pairs carry non-negligible orbital angular momentum in the degrees of freedom of relative movement in the type-II cases due to spatial symmetry breaking. We also show that the orbital angular momentum carried by photon-pairs in these degrees of freedom escapes detection in the traditional measurement scheme, which demands development of new techniques for further experimental investigations.

arXiv:0805.1924•May 13, 2008•0 citations

Entanglement of very high orbital angular momentum

Robert Fickler, Peizhe Li, Radek Łapkiewicz +5 more

Orbital angular momentum (OAM) of single photons represents a new optical degree of freedom for the entanglement of photons [1,2]. One physical realization of OAM carrying light beams are the so called Laguerre-Gaussian modes of light with the required helical phase structure. One big advantage over the well known polarization degree of freedom is the possibility of realizing entanglement between two photons with very high quantum numbers. However, the creation of photonic OAM entanglement using the widely used spontaneous parametric downconversion process is limited by the strongly reduced efficiency for higher momenta [3]. We have realized a novel method to create entanglement between two photons with a very high difference in their OAM quantum number and momentum respectively. Furthermore we have explored hybrid entanglement of photons in the OAM and polarization degree of freedom.

Frontiers in Optics•Jan 1, 2011•1 citation
In this work, we provide a complete theoretical and experimental study of a two-photon quantum state entangled in the orbital angular momentum (OAM) degree of freedom of the helical Mathieu-Gauss (HMG) modes. The state is generated by a type II spontaneous parametric down conversion (SPDC) process. Our analysis shows that the generated state is composed by the superposition of two symmetric Bell states with tunable contributions determined by the eccentricity parameter of the HMG modes. The predicted entangled state is confirmed experimentally by measuring the HMG modal joint probability of the SPDC two-photon state and the violation of Bell-type inequalities.
In this paper we provide a detailed theoretical and experimental analysis of the two-photon orbital-angular-momentum-entangled state, generated by a type-I spontaneous parametric down conversion (SPDC) process, when decomposed in terms of the helical Ince-Gauss (HIG) mode basis. By exploiting the unique characteristics of this modal basis we show how the probability detection of the photon pair can be tuned with the ellipticity parameter of the modes. We also show that on the HIG basis the SPDC state has the contribution of two different symmetric Bell states, and it is possible to maximize the probability of each HIG symmetric Bell state separately also by tuning the elipticity of the projected basis. The observed properties are confirmed experimentally by implementing measurements of the HIG modal joint probability of the SPDC two-photon state and Bell-type inequality violation experiments.
Abstract Quantum entanglement represents one of the most fascinating aspects of quantum mechanics and underpins the advancement of next-generation quantum-based technologies. Of particular interest is quantum entanglement in the spatial degree of freedom of light. As such, in this paper, we analyze a two-photon orbital angular momentum entangled state, decomposed in terms of helical Mathieu–Gauss ( HMG ) modes and generated through a type II spontaneous parametric down conversion process. Furthermore, a spatially-resolved heralded single photon detection system allowed the observation of the transverse spatial distribution of correlated HMG photons and the corroboration of their self-healing and non-diffractive properties. More precisely, we were able to corroborate that HMG photons maintain the same non-diffractive properties of classical HMG beams and that their time-averaged transverse field distribution reconstructs itself upon propagation in the presence of an opaque obstacle.
ENGLISH ABSTRACT: High-dimensional quantum entanglement offers an increase in information capacity per photon; a highly desirable property for quantum information processes such as quantum communication, computation and teleportation. As the orbital angular momentum (OAM) modes of light span an infinite-dimensional Hilbert space, they have become frontrunners in achieving entanglement in higher dimensions. In light of this, we investigate the potential of OAM entanglement of photons by controlling the parameters in both the generation and measurement systems. We show the experimental procedures and apparatus involved in generating and measuring entangled photons in two-dimensions. We verify important quantum tests such as the Einstein, Podolsky and Rosen (EPR) paradox using OAM and angle correlations, as well as a violation of a Bell-type inequality. By performing a full state tomography, we characterise our quantum state and show we have a pure, highly entangled quantum state. We demonstrate that this method can be extended to higher dimensions. The experimental techniques used to generate and measure OAM entanglement place an upper bound on the number of accessible OAM modes. As such, we investigate new methods in which to increase the spiral bandwidth of our generated quantum state. We alter the shape of the pump beam in spontaneous parametric down-conversion and demonstrate an effect on both OAM and angle correlations. We also made changes to the measurement scheme by projecting the photon pairs into the Bessel-Gaussian (BG) basis and demonstrate entanglement in this basis. We show that this method allows the measured spiral bandwidth to be optimised by simply varying the continuous radial parameter of the BG modes. We demonstrate that BG modes can be entangled in higher dimensions compared with the commonly used helical modes by calculating and comparing the linear entropy and fidelity for both modes. We also show that quantum entanglement can be accurately simulated using classical light using back-projection, which allows the study of projective measurements and predicts the strength of the coincidence correlations in an entanglement experiment. Finally, we make use of each of the techniques to demonstrate the effect of a perturbation on OAM entanglement measured in the BG basis. We investigate the self-healing property of BG beams and show that the classical property is translated to the quantum regime. By calculating the concurrence, we see that measured entanglement recovers after encountering an obstruction.
The bandwidth of any communication system, classical or quantum, is limited by the number of orthogonal states in which the information can be encoded. Quantum key distribution systems available commercially rely on the two-dimensional polarisation state of photons. Quantum computation has also been largely designed on the basis of qubits. However, a photon is endowed with other degrees of freedom, such as orbital angular momentum (OAM). OAM is an attractive basis to be used for quantum information because it is discrete and theoretically infinite-dimensional. This promises a higher information capacity per photon which can lead to more complex quantum computation protocols and more security and robustness for quantum cryptography. Entanglement of OAM naturally arises from spontaneous parametric down-conversion (SPDC). However, any practical experiment utilising the innately high-dimensional entanglement of the orbital angular momentum (OAM) state space of photons is subject to the modal capacity of the detection system. Only a finite subset of this space is accessible experimentally. Given such a constraint, we show that the number of measured, entangled OAM modes in photon pairs generated by SPDC can be increased by tuning the phase-matching conditions in the SPDC process. We achieve this by tuning the orientation angle of the nonlinear crystal generating the entangled photons.
Starting from the standard Hamiltonian describing the optical non-linear process of spontaneous parametric down-conversion, we theoretically show that the generated entangled photon-pairs carry non-negligible orbital angular momentum in the degrees of freedom of relative movement in the type-II cases due to spatial symmetry breaking. We also show that the orbital angular momentum carried by photon-pairs in these degrees of freedom escapes detection in the traditional measurement scheme, which demands development of new techniques for further experimental investigations.
Orbital angular momentum (OAM) of single photons represents a new optical degree of freedom for the entanglement of photons [1,2]. One physical realization of OAM carrying light beams are the so called Laguerre-Gaussian modes of light with the required helical phase structure. One big advantage over the well known polarization degree of freedom is the possibility of realizing entanglement between two photons with very high quantum numbers. However, the creation of photonic OAM entanglement using the widely used spontaneous parametric downconversion process is limited by the strongly reduced efficiency for higher momenta [3]. We have realized a novel method to create entanglement between two photons with a very high difference in their OAM quantum number and momentum respectively. Furthermore we have explored hybrid entanglement of photons in the OAM and polarization degree of freedom.