Certifying position-momentum entanglement at telecommunication wavelengths

Achatz, Lukas; Ortega, Evelyn; Dovzhik, Krishna; Shiozaki, R. F.; Fuenzalida, Jorge; Wengerovsky, Sören; Bohmann, Martin; Ursin, Rupert

doi:10.1088/1402-4896/ac44b5

Cited by 10 publications

(3 citation statements)

References 48 publications

(91 reference statements)

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“…Because of momentum conversation in the SPDC process, the signal and idler photons are emitted with opposite transverse momenta, resulting in q s = −q i , where q s (q i ) refers to the transverse momentum of the signal (idler) photon. En-tanglement in position-momentum for this particular source has already been shown in a previous work [26]. By utilizing a lens system in the far-field plane of the crystal, we imaged the momentum-correlations onto the front facet of a 411-m-long MCF.…”

Section: A Energy-time and Polarization Entanglement Analysissupporting

confidence: 54%

Simultaneous transmission of hyper-entanglement in 3 degrees of freedom through a multicore fiber

Achatz

Bulla²,

Ortega

et al. 2022

Preprint

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Entanglement distribution is at the heart of most quantum communication protocols. Inevitable loss of photons along quantum channels is a major obstacle for distributing entangled photons over long distances, as the no-cloning theorem forbids the information to simply be amplified along the way as is done in classical communication. It is therefore desirable for every successfully transmitted photon pair to carry as much entanglement as possible. Spontaneous parametric down-conversion (SPDC) creates photons entangled in multiple high-dimensional degrees of freedom simultaneously, often referred to as hyper-entanglement. In this work, we use a multicore fibre (MCF) to show that energy-time and polarization degrees of freedom can simultaneously be transmitted in multiple fibre cores, even maintaining path entanglement across the cores. We verify a fidelity to the ideal Bell state of at least 95$\%$ in all degrees of freedom. Furthermore, because the entangled photons are created with a center wavelength of 1560 nm, our approach can readily be integrated into modern telecommunication infrastructure, thus paving the way for high-rate quantum key distribution and many other entanglement-based quantum communication protocols.

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Section: A Energy-time and Polarization Entanglement Analysissupporting

confidence: 54%

Simultaneous transmission of hyper-entanglement in 3 degrees of freedom through a multicore fiber

Achatz

Bulla²,

Ortega

et al. 2022

Preprint

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“…Advances in telecommunication wavelengths have been made [274] thanks to steering, since recently it has been possible to certify EPR steering of photon pairs at these wavelengths, by using the process of parametric down conversion. For this kind of position-momentum entanglement, it is possible to calculate the dimensionality of entanglement, however, this depends on the length of the crystal.…”

Section: Quantum Steering Applicationsmentioning

confidence: 99%

Certification and applications of quantum nonlocal correlations

Piceno-Martínez,

Rosales-Zárate,

Ornelas-Cruces

2023

J. Phys. Photonics

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Entanglement and Einstein-Podolsky-Rosen (EPR) steering are nonlocal quantum correlations, which are relevant resources for quantum information protocols. EPR steering, or quantum steering, refers to the correlation where a party might “steer”, or modify, the state of another, which is spatially separated. Entanglement is a symmetric resource while steering is asymmetrical, since it depends on the direction of the effect. Due to these different characteristics and the therefore different possible applications, there has been both theoretical and experimental research on forms to certify the distinct quantum nonlocal correlations. In recent years, alongside the investigation on quantum correlations between two systems, there has been a great interest in investigating multipartite/multimode entanglement as well as steering, since they include a high dimension and it may be possible to store more information than in a single qubit. In this review, we will summarize the different criteria and measures that have been developed for the characterization of these two kinds of correlations. We first focus on bipartite entanglement and steering. We then review the progress that has been made in the investigation of multipartite quantum correlations. We revise the theoretical work in quantum nonlocal correlation witnesses and measures, which respectively allow one to certify that the system is entangled or presents EPR steering, and give a quantification of the content of these correlations in the system. Then, we briefly review the experiments that have been designed and that demonstrate multipartite quantum correlations. We also include applications in quantum information protocols, in particular in quantum teleportation and quantum cryptography.

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“…Discrete variable entanglement includes polarization [1] and orbital angular momentum [2], and have been studied and utilized in numerous applications as quantum key distribution [3], superdense coding [4], quantum teleportation [5], etc. The transverse position and momentum of the SPDC photons are the continuous spatial variables that have gained attention in recent years [6][7][8][9], and found applications in the field of quantum imaging [10][11][12][13][14][15], quantum metrology [16] and quantum communication [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic Spatial Entanglement

Patil¹,

Prabhakar²,

Biswas³

et al. 2022

Preprint

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The photon-pairs generated through spontaneous parametric down-conversion (SPDC) possess strong correlations in their transverse position and momentum degrees of freedom. For such photonpairs, the transverse position correlation length depends on the crystal thickness and the pump wavelength, whereas the transverse momentum correlation length depends on the beam waist and spatial coherence length of the pump. By controlling these parameters, it is possible to engineer the spatial entanglement. Here, we utilize the circular asymmetry of the pump by using an elliptical-Gaussian beam to change the degree of entanglement in transverse directions, which we call anisotropic entanglement. We show the interrelation between the degree of anisotropic entanglement and the asymmetry in the beam width. In addition, we also show that for a highly asymmetric pump beam, the entanglement along the y direction completely vanishes, whereas the entanglement in x direction remains intact.

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Certifying position-momentum entanglement at telecommunication wavelengths

Cited by 10 publications

References 48 publications

Simultaneous transmission of hyper-entanglement in 3 degrees of freedom through a multicore fiber

Simultaneous transmission of hyper-entanglement in 3 degrees of freedom through a multicore fiber

Certification and applications of quantum nonlocal correlations

Anisotropic Spatial Entanglement

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