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

Nonlocal splitting of photons on a nonlinear chip

Frank Setzpfandt, Alexander S. Solntsev, Andrey A. Sukhorukov

Published Nov 29, 2016• 3 citations
Publisher

Abstract

In spontaneous parametric downconversion (SPDC), a pump photon spontaneously splits into signal and idler photons in media with quadratic nonlinearity. This phenomenon is the most widely utilized source of entangled photons with multiple applications in quantum information technology. SPDC on a chip is usually treated as a local process, meaning that signal and idler photons are created in the same position at which the pump photon is destroyed. We reveal that this locality condition can be violated in an array of coupled waveguides. By utilizing higher-order modes of individual waveguides, it is possible to destroy a pump photon in one waveguide and to generate signal and idler photons in other waveguides. This phenomenon of nonlocal photon-pair generation opens new opportunities for the engineering of spatial photon entanglement.

DOI
10.1364/ol.41.005604

Related papers

Nonlocal Parametric Down-Conversion in Multi-Mode Nonlinear Waveguide Arrays

Frank Setzpfandt, Alexander S. Solntsev, Thomas Pertsch +1 more

The generation of multi-photon quantum states in integrated waveguiding structures provides a route to the creation of quantum optical chips. In particular, the simultaneous generation of photons through spontaneous parametric down-conversion (SPDC) and their quantum walks in nonlinear waveguide arrays (WGAs) can be used to produce strongly spatially entangled biphoton states [1] with applications for quantum search algorithms [2]. Whereas up to now only arrays of single-mode nonlinear waveguides have been considered for SPDC, in general the waveguides may support several guided modes, which were demonstrated to strongly affect nonlinear wave mixing in the classical regime [3]. Here we show that using higher order modes for SPDC has a significant influence on the generated two-photon states and gives additional means to control them. In particular, we employ the symmetry of the modes to engineer effectively nonlocal photon pair generation by SPDC.

European Quantum Electronics Conference (EQEC)•Jan 1, 2015•0 citations

Quantum, Nonlinear, and Nano Optics Meet

Maria V. Chekhova

Quantum states of light, such as single photons, pairs of entangled photons, and squeezed light are a key resource for photonic quantum technologies. All these states can be obtained via the nonlinear optical effect of spontaneous parametric down-conversion (SPDC). In SPDC, a higher-energy photon of a coherent beam (pump) splits in two lower-energy daughter photons, called signal and idler. The photons of such a pair can be entangled in polarization, time/frequency, and position/momentum. Efficient generation of photon pairs requires a high second-order susceptibility$\chi^{(2)}$of the material where it occurs, and the phase matching between the pump and the down-converted photons.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 23, 2025•0 citations

Spontaneous parametric down-conversion in asymmetric couplers: Photon purity enhancement and intrinsic spectral filtering

Philip B. Main, Peter J. Mosley, Andrey V. Gorbach

We analyze the process of photon-pair generation via spontaneous parametric down-conversion in a quadratic nonlinear asymmetric waveguide coupler. The two waveguides have different geometry, such that light coupling only occurs within a narrow bandwidth of one of the generated (signal) photon modes, while the other (idler) photon together with the pump stay localized in one (driven) arm of the coupler. We demonstrate that such a setup represents a powerful and flexible tool for engineering spectral properties of generated photon pairs. Mode hybridization and dispersion of coupling can be utilized for shifting the balance between group velocities of interacting pump, signal, and idler fields, subsequently leading to a significant increase of spectral factorizability (purity) of photons. We also show that for interaction lengths shorter than one beat length, generated pairs with signal photon being localized in the auxiliary (not pumped) arm of the coupler appear to be spectrally localized in both signal and idler components. The bandwidth of such intrinsic filtering of generated photons can be controlled by several geometrical parameters.

arXiv:1907.09215•Physical Review A•Nov 7, 2019•8 citations

Generation and manipulation of quantum light using bulk nonlinear metamaterials

Ady Arie

In the process of Spontaneous Parametric Down Conversion (SPDC), a pump photon spontaneously splits inside a quadratic nonlinear crystal to signal and idler photons. By spatially modulating the nonlinear coefficient, we form a bulk nonlinear metamaterial that can shape the first and second order correlations of the down-converted signal and idler photons in either the spatial domain or the spectral domains. These degrees of freedom span a multi-dimensional Hilbert space, which is beneficial for quantum information applications. Recently, we have designed and fabricated, using electric field poling, bulk nonlinear metamaterials in KTiOPO4, for generating spatially entangled signal-idler pairs. This includes a bi-photon Bell state in the Hermite-Gauss basis, or a state with 3 dominant pairs of coincidences, approximating a bi-photon qutrit. As for the spectral domain, we generated a variety of quantum states: high purity frequency uncorrelated states, frequency-bin Bell states and frequency entangled bi-photon qudit states. By increasing the pump power, we reach the regime of bright squeezed vacuum sources, enabling the generation of a square cluster state in the frequency domain.

SPIE Metamaterials Conference•Jun 10, 2024•0 citations

Theory for quantum state of photon pairs generated from spontaneous parametric down-conversion nonlinear process

Ruiqi Wang, H. R. Zhang

A theory is presented for the quantum state of photon pairs generated from spontaneous parametric down-conversion nonlinear process. In this theory, the influence of the final sizes of nonlinear optical crystals on optical eigenmodes is explicitly taken into consideration. It was found that these photon pairs are not in entangled quantum states. Polarization correlations between the signal beam and the idler beam are explained. It is also shown that the two photons generated from SPDC are not spatially separated, therefore the polarization correlation between the signal and idler beams is not an evidence for quantum non-locality.

arXiv:quant-ph/0602121•Optics and Spectroscopy•Jul 1, 2007•3 citations

Counterpropagating entangled photons in a periodically poled nonlinear waveguide

Mark C. Booth, Mete Atatüre, Giovanni Di Giuseppe +3 more

Entangled photons, which may be generated through the process of spontaneous parametric down-conversion (SPDC) in a crystal with /spl chi//sup (2)/ nonlinearity, have long been in the spotlight for quantum-optics experiments. The generation of entangled photons by quasi-phase matching (QPM) in lithium niobate offers the promise of increased photon-pair production and, with the integration of a waveguide structure, control of the spatial characteristics of the down-converted photons. It turns out that the use of a waveguide structure, in conjunction with periodic poling to achieve quasi-phase matching, offers another critically important feature: the possibility of generating counterpropagating signal and idler photons. We consider the conditions required for generating counterpropagating photon beams and explore some of the unique properties of this source of light using a periodically poled LiNbO/sub 3/ waveguide.

IEEE Lasers and Electro-Optics Society Annual Meeting (LEOS)•Jun 26, 2003•2 citations
In spontaneous parametric downconversion (SPDC), a pump photon spontaneously splits into signal and idler photons in media with quadratic nonlinearity. This phenomenon is the most widely utilized source of entangled photons with multiple applications in quantum information technology. SPDC on a chip is usually treated as a local process, meaning that signal and idler photons are created in the same position at which the pump photon is destroyed. We reveal that this locality condition can be violated in an array of coupled waveguides. By utilizing higher-order modes of individual waveguides, it is possible to destroy a pump photon in one waveguide and to generate signal and idler photons in other waveguides. This phenomenon of nonlocal photon-pair generation opens new opportunities for the engineering of spatial photon entanglement.
The generation of multi-photon quantum states in integrated waveguiding structures provides a route to the creation of quantum optical chips. In particular, the simultaneous generation of photons through spontaneous parametric down-conversion (SPDC) and their quantum walks in nonlinear waveguide arrays (WGAs) can be used to produce strongly spatially entangled biphoton states [1] with applications for quantum search algorithms [2]. Whereas up to now only arrays of single-mode nonlinear waveguides have been considered for SPDC, in general the waveguides may support several guided modes, which were demonstrated to strongly affect nonlinear wave mixing in the classical regime [3]. Here we show that using higher order modes for SPDC has a significant influence on the generated two-photon states and gives additional means to control them. In particular, we employ the symmetry of the modes to engineer effectively nonlocal photon pair generation by SPDC.
Quantum states of light, such as single photons, pairs of entangled photons, and squeezed light are a key resource for photonic quantum technologies. All these states can be obtained via the nonlinear optical effect of spontaneous parametric down-conversion (SPDC). In SPDC, a higher-energy photon of a coherent beam (pump) splits in two lower-energy daughter photons, called signal and idler. The photons of such a pair can be entangled in polarization, time/frequency, and position/momentum. Efficient generation of photon pairs requires a high second-order susceptibilityχ(2)\chi^{(2)}χ(2)of the material where it occurs, and the phase matching between the pump and the down-converted photons.
We analyze the process of photon-pair generation via spontaneous parametric down-conversion in a quadratic nonlinear asymmetric waveguide coupler. The two waveguides have different geometry, such that light coupling only occurs within a narrow bandwidth of one of the generated (signal) photon modes, while the other (idler) photon together with the pump stay localized in one (driven) arm of the coupler. We demonstrate that such a setup represents a powerful and flexible tool for engineering spectral properties of generated photon pairs. Mode hybridization and dispersion of coupling can be utilized for shifting the balance between group velocities of interacting pump, signal, and idler fields, subsequently leading to a significant increase of spectral factorizability (purity) of photons. We also show that for interaction lengths shorter than one beat length, generated pairs with signal photon being localized in the auxiliary (not pumped) arm of the coupler appear to be spectrally localized in both signal and idler components. The bandwidth of such intrinsic filtering of generated photons can be controlled by several geometrical parameters.
In the process of Spontaneous Parametric Down Conversion (SPDC), a pump photon spontaneously splits inside a quadratic nonlinear crystal to signal and idler photons. By spatially modulating the nonlinear coefficient, we form a bulk nonlinear metamaterial that can shape the first and second order correlations of the down-converted signal and idler photons in either the spatial domain or the spectral domains. These degrees of freedom span a multi-dimensional Hilbert space, which is beneficial for quantum information applications. Recently, we have designed and fabricated, using electric field poling, bulk nonlinear metamaterials in KTiOPO4, for generating spatially entangled signal-idler pairs. This includes a bi-photon Bell state in the Hermite-Gauss basis, or a state with 3 dominant pairs of coincidences, approximating a bi-photon qutrit. As for the spectral domain, we generated a variety of quantum states: high purity frequency uncorrelated states, frequency-bin Bell states and frequency entangled bi-photon qudit states. By increasing the pump power, we reach the regime of bright squeezed vacuum sources, enabling the generation of a square cluster state in the frequency domain.
A theory is presented for the quantum state of photon pairs generated from spontaneous parametric down-conversion nonlinear process. In this theory, the influence of the final sizes of nonlinear optical crystals on optical eigenmodes is explicitly taken into consideration. It was found that these photon pairs are not in entangled quantum states. Polarization correlations between the signal beam and the idler beam are explained. It is also shown that the two photons generated from SPDC are not spatially separated, therefore the polarization correlation between the signal and idler beams is not an evidence for quantum non-locality.
Entangled photons, which may be generated through the process of spontaneous parametric down-conversion (SPDC) in a crystal with /spl chi//sup (2)/ nonlinearity, have long been in the spotlight for quantum-optics experiments. The generation of entangled photons by quasi-phase matching (QPM) in lithium niobate offers the promise of increased photon-pair production and, with the integration of a waveguide structure, control of the spatial characteristics of the down-converted photons. It turns out that the use of a waveguide structure, in conjunction with periodic poling to achieve quasi-phase matching, offers another critically important feature: the possibility of generating counterpropagating signal and idler photons. We consider the conditions required for generating counterpropagating photon beams and explore some of the unique properties of this source of light using a periodically poled LiNbO/sub 3/ waveguide.