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

arXiv:2104.04464 · Optics Letters

Low random duty-cycle errors in periodically poled KTP revealed by sum-frequency generation

Felix Mann, Helen M. Chrzanowski, Sven Ramelow

Published Jun 1, 2021• 8 citations
arXivHTMLPDF

Abstract

Low-noise quantum frequency conversion in periodically poled nonlinear crystals has proved challenging when the pump wavelength is shorter than the target wavelength. This is—at least in large part—a consequence of the parasitic spontaneous parametric downconversion of pump photons, whose efficiency is increased by fabrication errors in the periodic poling. Here we characterize the poling quality of commercial periodically poled bulk potassium titanyl phosphate (ppKTP) by measuring the sum-frequency generation (SFG) efficiency over a large phase mismatch range from 0 to more than 400 π . Over the probed range, the SFG efficiency behaves nearly ideally and drops to a normalized efficiency of 10 − 6 . Our results demonstrate that any background pedestal that would be formed by random duty-cycle errors in ppKTP is substantially reduced when compared to periodically poled lithium niobate. The standard deviation of the random duty-cycle errors can be estimated to be smaller than 2% of the domain length. From this, we expect a noise spectral density that is at least 1 order of magnitude smaller than that of current state-of-the-art single-step frequency converters.

DOI
10.1364/ol.427464

Related papers

Low random duty-cycle errors in periodically-poled KTP revealed by sum-frequency generation

Felix Mann, Helen M. Chrzanowski, Sven Ramelow

Single photons from nitrogen-vacancy centers in diamond are a promising building block in the realisation of quantum networks [1] [2] . However quantum frequency conversion (QFC) [3] of these red single photons remains an indispensable requirement, allowing the scale of potential networks to achieve distances accessible with telecom fibers [4] . QFC can be realised in a periodically-poled nonlinear crystal with a χ (2) -nonlinearity using sum-frequency or difference-frequency generation (SFG/DFG). A major problem for scenarios where the pump wavelength is shorter than the target wavelength is the parasitic spontaneous parametric down-conversion of pump photons, whose efficiency is increased by fabrication errors of the periodic poling: It was shown by [5] that these fabrication errors, namely random duty cycle errors [6] , introduce a pedestal in the phase-matching curve at detunings far from the design wavelengths.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 21, 2021•2 citations

Noise analysis of a quasi-phase-matched quantum frequency converter and higher-order counter-propagating SPDC

Felix Mann, Helen M. Chrzanowski, Felipe Lucas Gewers +2 more

Quantum frequency conversion (QFC) will be an indispensable ingredient in future quantum technologies. For example, large-scale fibre-based quantum networks will require QFC to interconnect heterogeneous building blocks like emitters, channels, memories, and detectors. The performance of existing QFC devices – typically realized in periodically poled nonlinear crystals – is often severely limited by parasitic noise that arises when the pump wavelength lies between the inter-converted wavelengths. Here we comprehensively investigate the noise spectrum of a QFC device pumped by a CW 1064 nm laser. The converter was realized as a bulk periodically poled potassium titanyl phosphate (ppKTP) crystal quasi-phase-matched for conversion between 637 nm and 1587 nm, which was also polished and coated to resonantly enhance the pump field by a factor of 50. While Raman scattering dominates the noise background from 1140 nm to 1330 nm, at larger energy shifts (beyond 60 THz), parasitic spontaneous parametric down-conversion (SPDC) is the strongest noise source. Further, the noise spectrum was contaminated by a regular succession of narrow-band peaks, which we attribute to a heretofore unidentified higher-order counter-propagating SPDC processes – with quasi-phase-matching orders up to 44 evident in our measurements. This work provides a comprehensive overview of the limiting noise sources in QFC devices that use quasi-phase-matched crystals and will prove an invaluable resource in guiding their future development.

Optics Express•Oct 15, 2024•5 citations

Noise analysis of a quasi-phase-matched quantum frequency converter and higher-order counter-propagating SPDC

Felix Mann, Helen M. Chrzanowski, Felipe Lucas Gewers +2 more

Quantum frequency conversion (QFC) will be an indispensable ingredient in future quantum technologies. For example, large-scale fibre-based quantum networks will require QFC to interconnect heterogeneous building blocks like emitters, channels, memories and detectors. The performance of existing QFC devices - typically realised in periodically-poled nonlinear crystals - is often severely limited by parasitic noise that arises when the pump wavelength lies between the inter-converted wavelengths. Here we comprehensively investigate the noise spectrum of a QFC device pumped by a CW 1064 nm laser. The converter was realised as a bulk periodically-poled potassium titanyl phosphate (ppKTP) crystal quasi-phase-matched for conversion between 637 nm and 1587 nm, which was also polished and coated to resonantly enhance the pump field by a factor of 50. While Raman scattering dominates the noise background from 1140 nm to 1330 nm, at larger energy shifts (beyond 60 THz), parasitic spontaneous parametric down-conversion (SPDC) is the strongest noise source. Further, the noise spectrum was contaminated by a regular succession of narrow-band peaks, which we attribute to a heretofore unidentified higher-order counter-propagating SPDC processes - with quasi-phase-matching orders up to 44 evident in our measurements. This work provides a comprehensive overview of the limiting noise sources in QFC devices that use quasi-phase-matched crystals and will prove an invaluable resource in guiding their future development.

arXiv:2407.03845•Jul 4, 2024•0 citations

Low-noise quantum frequency conversion in a monolithic cavity with bulk periodically poled potassium titanyl phosphate

Felix Mann, Helen M. Chrzanowski, Felipe Lucas Gewers +2 more

Interfacing the different building blocks of a future large-scale quantum network will require efficient and noiseless frequency conversion of quantum light. Nitrogen-vacancy centers in diamond are a leading candidate to form the nodes of such a network. However, the performance of a suitable converter remains a bottleneck, with existing demonstrations severely limited by parasitic noise arising at the target telecommunication wavelength. Here we demonstrate a platform for efficient low-noise quantum frequency conversion based on a monolithic bulk periodically poled potassium titanyl phosphate cavity and show its suitability for the conversion of 637-nm single photons from nitrogen-vacancy centers in diamond to telecommunication wavelengths. By resonantly enhancing the power of an off-the-shelf pump laser, we achieve an internal conversion efficiency of $(72.3\ifmmode\pm\else\textpm\fi{}0.4)\mathrm{%}$ while generating noise of only $(110\ifmmode\pm\else\textpm\fi{}4)\phantom{\rule{0.2em}{0ex}}\mathrm{kHz}/\mathrm{nm}$ at the target wavelength without the need for any active stabilization. This constitutes a fivefold reduction in noise over existing state-of-the-art single-step converters at these wavelengths. We verify the almost-ideal preservation of nonclassical correlations by converting photons from a spontaneous-parametric-down-conversion source and moreover show the preservation of time-energy entanglement via Franson interferometry.

arXiv:2304.13459•Physical Review Applied•Nov 3, 2023•28 citations

Spectral engineering by Gaussian phase-matching for quantum photonics

P. Ben Dixon, Jeffrey H. Shapiro, Franco N. C. Wong

We demonstrate Gaussian-shaped phase matching of a periodically-poled potassium titanyl phosphate (PPKTP) crystal by imposing a custom duty-cycle pattern on its grating structure while keeping the grating period fixed. The PPKTP's phase-matching characteristics are verified through optical difference-frequency generation measurements, showing good agreement with expected values based on our design parameters. Our theoretical analysis predicts that under extended phase-matching conditions the custom-poled PPKTP crystal is capable of generating heralded single photons with a spectral purity of 97%, and can reach as high as 99.5% with gentle spectral filtering, something that is highly desirable for photonic quantum information processing applications.

Optics Express•Mar 1, 2013•91 citations

The single-cycle biphotons generated by SPDC in chirped QPM PPKTP crystal

Wang Jinbao, Lin Haibo

In this paper, we have studied the process of monochromatic pump light in linearly chirped Periodically Poled [Formula: see text] (PPKTP) nonlinear crystal to generate single-cycle biphotons under Quasi-Phase-Matching (QPM) conditions through a Spontaneous Parametric Down-Conversion (SPDC). A detailed analysis of the phase mismatching function reveals that in PPKTP crystals, for the proper frequency range, the phase mismatching [Formula: see text] is stable and relatively close to 0 due to the relatively stable refractive index, and therefore has a good phase matching effect. Even when the chirp rate becomes small, it is able to produce single-cycle biphotons due to the near-perfect phase matching. Of course, as the chirp rate increases, the frequency response range becomes wider, the temporal width is narrower, and the number of cycles is smaller.

Journal of Nonlinear Optical Physics & Materials•Feb 18, 2024•0 citations
Low-noise quantum frequency conversion in periodically poled nonlinear crystals has proved challenging when the pump wavelength is shorter than the target wavelength. This is—at least in large part—a consequence of the parasitic spontaneous parametric downconversion of pump photons, whose efficiency is increased by fabrication errors in the periodic poling. Here we characterize the poling quality of commercial periodically poled bulk potassium titanyl phosphate (ppKTP) by measuring the sum-frequency generation (SFG) efficiency over a large phase mismatch range from 0 to more than 400 π . Over the probed range, the SFG efficiency behaves nearly ideally and drops to a normalized efficiency of 10 − 6 . Our results demonstrate that any background pedestal that would be formed by random duty-cycle errors in ppKTP is substantially reduced when compared to periodically poled lithium niobate. The standard deviation of the random duty-cycle errors can be estimated to be smaller than 2% of the domain length. From this, we expect a noise spectral density that is at least 1 order of magnitude smaller than that of current state-of-the-art single-step frequency converters.
Single photons from nitrogen-vacancy centers in diamond are a promising building block in the realisation of quantum networks [1] [2] . However quantum frequency conversion (QFC) [3] of these red single photons remains an indispensable requirement, allowing the scale of potential networks to achieve distances accessible with telecom fibers [4] . QFC can be realised in a periodically-poled nonlinear crystal with a χ (2) -nonlinearity using sum-frequency or difference-frequency generation (SFG/DFG). A major problem for scenarios where the pump wavelength is shorter than the target wavelength is the parasitic spontaneous parametric down-conversion of pump photons, whose efficiency is increased by fabrication errors of the periodic poling: It was shown by [5] that these fabrication errors, namely random duty cycle errors [6] , introduce a pedestal in the phase-matching curve at detunings far from the design wavelengths.
Quantum frequency conversion (QFC) will be an indispensable ingredient in future quantum technologies. For example, large-scale fibre-based quantum networks will require QFC to interconnect heterogeneous building blocks like emitters, channels, memories, and detectors. The performance of existing QFC devices – typically realized in periodically poled nonlinear crystals – is often severely limited by parasitic noise that arises when the pump wavelength lies between the inter-converted wavelengths. Here we comprehensively investigate the noise spectrum of a QFC device pumped by a CW 1064 nm laser. The converter was realized as a bulk periodically poled potassium titanyl phosphate (ppKTP) crystal quasi-phase-matched for conversion between 637 nm and 1587 nm, which was also polished and coated to resonantly enhance the pump field by a factor of 50. While Raman scattering dominates the noise background from 1140 nm to 1330 nm, at larger energy shifts (beyond 60 THz), parasitic spontaneous parametric down-conversion (SPDC) is the strongest noise source. Further, the noise spectrum was contaminated by a regular succession of narrow-band peaks, which we attribute to a heretofore unidentified higher-order counter-propagating SPDC processes – with quasi-phase-matching orders up to 44 evident in our measurements. This work provides a comprehensive overview of the limiting noise sources in QFC devices that use quasi-phase-matched crystals and will prove an invaluable resource in guiding their future development.
Quantum frequency conversion (QFC) will be an indispensable ingredient in future quantum technologies. For example, large-scale fibre-based quantum networks will require QFC to interconnect heterogeneous building blocks like emitters, channels, memories and detectors. The performance of existing QFC devices - typically realised in periodically-poled nonlinear crystals - is often severely limited by parasitic noise that arises when the pump wavelength lies between the inter-converted wavelengths. Here we comprehensively investigate the noise spectrum of a QFC device pumped by a CW 1064 nm laser. The converter was realised as a bulk periodically-poled potassium titanyl phosphate (ppKTP) crystal quasi-phase-matched for conversion between 637 nm and 1587 nm, which was also polished and coated to resonantly enhance the pump field by a factor of 50. While Raman scattering dominates the noise background from 1140 nm to 1330 nm, at larger energy shifts (beyond 60 THz), parasitic spontaneous parametric down-conversion (SPDC) is the strongest noise source. Further, the noise spectrum was contaminated by a regular succession of narrow-band peaks, which we attribute to a heretofore unidentified higher-order counter-propagating SPDC processes - with quasi-phase-matching orders up to 44 evident in our measurements. This work provides a comprehensive overview of the limiting noise sources in QFC devices that use quasi-phase-matched crystals and will prove an invaluable resource in guiding their future development.
Interfacing the different building blocks of a future large-scale quantum network will require efficient and noiseless frequency conversion of quantum light. Nitrogen-vacancy centers in diamond are a leading candidate to form the nodes of such a network. However, the performance of a suitable converter remains a bottleneck, with existing demonstrations severely limited by parasitic noise arising at the target telecommunication wavelength. Here we demonstrate a platform for efficient low-noise quantum frequency conversion based on a monolithic bulk periodically poled potassium titanyl phosphate cavity and show its suitability for the conversion of 637-nm single photons from nitrogen-vacancy centers in diamond to telecommunication wavelengths. By resonantly enhancing the power of an off-the-shelf pump laser, we achieve an internal conversion efficiency of $(72.3\ifmmode\pm\else\textpm\fi{}0.4)\mathrm{%}$ while generating noise of only $(110\ifmmode\pm\else\textpm\fi{}4)\phantom{\rule{0.2em}{0ex}}\mathrm{kHz}/\mathrm{nm}$ at the target wavelength without the need for any active stabilization. This constitutes a fivefold reduction in noise over existing state-of-the-art single-step converters at these wavelengths. We verify the almost-ideal preservation of nonclassical correlations by converting photons from a spontaneous-parametric-down-conversion source and moreover show the preservation of time-energy entanglement via Franson interferometry.
We demonstrate Gaussian-shaped phase matching of a periodically-poled potassium titanyl phosphate (PPKTP) crystal by imposing a custom duty-cycle pattern on its grating structure while keeping the grating period fixed. The PPKTP's phase-matching characteristics are verified through optical difference-frequency generation measurements, showing good agreement with expected values based on our design parameters. Our theoretical analysis predicts that under extended phase-matching conditions the custom-poled PPKTP crystal is capable of generating heralded single photons with a spectral purity of 97%, and can reach as high as 99.5% with gentle spectral filtering, something that is highly desirable for photonic quantum information processing applications.
In this paper, we have studied the process of monochromatic pump light in linearly chirped Periodically Poled [Formula: see text] (PPKTP) nonlinear crystal to generate single-cycle biphotons under Quasi-Phase-Matching (QPM) conditions through a Spontaneous Parametric Down-Conversion (SPDC). A detailed analysis of the phase mismatching function reveals that in PPKTP crystals, for the proper frequency range, the phase mismatching [Formula: see text] is stable and relatively close to 0 due to the relatively stable refractive index, and therefore has a good phase matching effect. Even when the chirp rate becomes small, it is able to produce single-cycle biphotons due to the near-perfect phase matching. Of course, as the chirp rate increases, the frequency response range becomes wider, the temporal width is narrower, and the number of cycles is smaller.