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

Increasing Shannon dimensionality by hyperentanglement of spin and fractional orbital angular momentum

Lixiang Chen, Weilong She

Published Jun 9, 2009• 23 citations
Publisher

Abstract

We propose a single-photon spin-orbit entangled state analyzer for investigating the effective dimensionality of the Hilbert space spanned by spin and orbital angular momentum (OAM) states of twin photons from a spontaneous parametric downconversion (SPDC). The Pancharatnam-Berry phase element, the key element called a q plate equipped in the analyzer, induces the coupling between spin and OAM. It is found that the Shannon dimensionality of quantum channels in SPDC can be evidently increased owing to the spin-orbit hyperentanglement.

DOI
10.1364/ol.34.001855

Related papers

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

Shannon Dimensionality of Quantum Channels and Its Application to Photon Entanglement

J. B. Pors, Sumant S. R. Oemrawsingh, Andrea Aiello +4 more

We introduce the concept of Shannon dimensionality D as a new way to quantify bipartite entanglement as measured in an experiment. This is applied to orbital-angular-momentum entanglement of two photons, using two state analyzers composed of a rotatable angular-sector phase plate that is lens coupled to a single-mode fiber. We can deduce the value of D directly from the observed two-photon coincidence fringe. In our experiment, D varies between 2 and 6, depending on the experimental conditions. We predict how the Shannon dimensionality evolves when the number of angular sectors imprinted in the phase plate is increased and anticipate that D approximately 50 is experimentally within reach.

arXiv:0808.3325•Physical Review Letters•Sep 18, 2008•84 citations

Angular entanglement of two photons

E. R. Eliel, Bart-Jan Pors, Sumant S. R. Oemrawsingh +3 more

Most protocols for quantum communication rely on entanglement between qubits. In this contribution we report on an experiment on angular entanglement of two photons. We introduce a quantifier of the dimensionality of the entanglement, using concepts from classical information theory. This Shannon dimensionality gives the effective number of information channels. We exploit the orbital-angular-momentum degree of freedom of photons that emerge from a parametric down-conversion source. The number of entangled modes, known as the Schmidt number, is of order 40. The entanglement is analyzed with a pair of angular state projectors, each consisting of a phase plate, a single-mode fiber and a single-photon detector. The phase plates are rotated about their axes and we record the photon coincidence rate as a function of their independent orientations. The coincidence count rates depend only on the relative orientation of the analyzers. This is a key signature of entanglement.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 1, 2009•0 citations

Single-photon spin-orbit entanglement violating a Bell-like inequality

Lixiang Chen, Weilong She

Single photons emerging from Pancharatnam-Berry phase optical elements (q plates) exhibit entanglement in the degrees of freedom of spin and orbital angular momentum. We put forward an experimental scheme for probing the spin-orbit correlations of single photons. It is found that the Clauser-Horne-Shimony-Holt parameter S for the single-photon spin-orbit entangled state could be as high as 2√2, evidently violating the Bell-like inequality and thus invalidating the noncontextual hidden variable theories.

arXiv:0911.0544•Journal of the Optical Society of America B•Jan 22, 2010•52 citations

Experimental Demonstration of Fractional Orbital Angular Momentum Entanglement of Two Photons

Sumant S. R. Oemrawsingh, Xuan Ma, D. Voigt +4 more

The singular nature of a noninteger spiral phase plate allows easy manipulation of spatial degrees of freedom of photon states. Using two such devices, we have observed very high-dimensional spatial entanglement of twin photons generated by spontaneous parametric down-conversion.

arXiv:quant-ph/0506253•Physical Review Letters•Dec 8, 2005•243 citations

Orbital angular momentum correlations of entangled paired photons

Clara I. Osorio, Gabriel Molina‐Terriza, Juan P. Torres

The generation of paired photons entangled in the spatial degree of freedom, i.e., in orbital angular momentum, offers a convenient physical resource to investigate the nature of entanglement in a multidimensional Hilbert space with controllable dimensionality. The two main physical processes that generate pairs of photons which show correlations in orbital angular momentum are (a) spontaneous parametric down-conversion (SPDC), and (b) Raman transitions induced in atomic ensembles. One question naturally arises: what kinds of correlations exist between the orbital angular momentum of the generated photons? The answer might be different if we consider the whole quantum state of the generated photons, i.e., all possible directions where the pairs of photons can be emitted, or if we consider only a small section of the full set of directions.

Journal of Optics A Pure and Applied Optics•Aug 5, 2009•14 citations
We propose a single-photon spin-orbit entangled state analyzer for investigating the effective dimensionality of the Hilbert space spanned by spin and orbital angular momentum (OAM) states of twin photons from a spontaneous parametric downconversion (SPDC). The Pancharatnam-Berry phase element, the key element called a q plate equipped in the analyzer, induces the coupling between spin and OAM. It is found that the Shannon dimensionality of quantum channels in SPDC can be evidently increased owing to the spin-orbit hyperentanglement.
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.
We introduce the concept of Shannon dimensionality D as a new way to quantify bipartite entanglement as measured in an experiment. This is applied to orbital-angular-momentum entanglement of two photons, using two state analyzers composed of a rotatable angular-sector phase plate that is lens coupled to a single-mode fiber. We can deduce the value of D directly from the observed two-photon coincidence fringe. In our experiment, D varies between 2 and 6, depending on the experimental conditions. We predict how the Shannon dimensionality evolves when the number of angular sectors imprinted in the phase plate is increased and anticipate that D approximately 50 is experimentally within reach.
Most protocols for quantum communication rely on entanglement between qubits. In this contribution we report on an experiment on angular entanglement of two photons. We introduce a quantifier of the dimensionality of the entanglement, using concepts from classical information theory. This Shannon dimensionality gives the effective number of information channels. We exploit the orbital-angular-momentum degree of freedom of photons that emerge from a parametric down-conversion source. The number of entangled modes, known as the Schmidt number, is of order 40. The entanglement is analyzed with a pair of angular state projectors, each consisting of a phase plate, a single-mode fiber and a single-photon detector. The phase plates are rotated about their axes and we record the photon coincidence rate as a function of their independent orientations. The coincidence count rates depend only on the relative orientation of the analyzers. This is a key signature of entanglement.
Single photons emerging from Pancharatnam-Berry phase optical elements (q plates) exhibit entanglement in the degrees of freedom of spin and orbital angular momentum. We put forward an experimental scheme for probing the spin-orbit correlations of single photons. It is found that the Clauser-Horne-Shimony-Holt parameter S for the single-photon spin-orbit entangled state could be as high as 2√2, evidently violating the Bell-like inequality and thus invalidating the noncontextual hidden variable theories.
The generation of paired photons entangled in the spatial degree of freedom, i.e., in orbital angular momentum, offers a convenient physical resource to investigate the nature of entanglement in a multidimensional Hilbert space with controllable dimensionality. The two main physical processes that generate pairs of photons which show correlations in orbital angular momentum are (a) spontaneous parametric down-conversion (SPDC), and (b) Raman transitions induced in atomic ensembles. One question naturally arises: what kinds of correlations exist between the orbital angular momentum of the generated photons? The answer might be different if we consider the whole quantum state of the generated photons, i.e., all possible directions where the pairs of photons can be emitted, or if we consider only a small section of the full set of directions.