NIST - National Institute of Standards and Technology

04/20/2026 | Press release | Archived content

Domain-engineered, aperiodically-poled KTiOPO4 for polarization-entangled photons

Published
April 20, 2026

Author(s)

Paulina Kuo, Sesha Challa, Anouar Rahmouni, Dileep Venkatarama Reddy, Ori Levin, Noa Bloch

Abstract

We demonstrate a high-quality source of polarization-entangled photons in aperiodically-poled KTiOPO_4 (KTP). The crystal is based on a phase-modulated domain-engineered design that allows two simultaneous downconversion processes, where the two processes correspond to the two terms of the entangled-photon state. We characterized the temperature tuning of both the spectral response and the polarization-fringe visibility for spontaneous parametric downconversion (SPDC) using this crystal. At the optimum temperature where wavelength distinguishability of the two SPDC processes is smallest, we obtained average polarization-entanglement visibility 0.984 ± 0.003 with a measured Clauser-Horne-Shimony-Holt (CHSH) parameter S = 2.801 ± 0.014. We also discuss the effects of the relative phase in the entangled-photon state and present a new way to compensate for these effects to obtain high polarization-entanglement visibility.
Citation
Optical Materials Express
Pub Type
Journals

Keywords

spontaneous parametric downconversion, quantum networking

Citation

Kuo, P. , Challa, S. , Rahmouni, A. , Venkatarama Reddy, D. , Levin, O. and Bloch, N. (2026), Domain-engineered, aperiodically-poled KTiOPO4 for polarization-entangled photons, Optical Materials Express, [online], https://doi.org/10.1364/OME.587330, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961273 (Accessed April 25, 2026)
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NIST - National Institute of Standards and Technology published this content on April 20, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on April 25, 2026 at 09:21 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]