© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

EPJ Web of Conferences

Towards spontaneous parametric down-conversion at low temperatures

D O Akat’ev, Kirill N. Boldyrev, N. N. Kuzmin, Латыпов Ильнур Зиннурович, Marina N. Popova, Andrey V. Shkalikov, А. А. Калачев

Published Jan 1, 2017• 0 citations

Abstract

The possibility of observing spontaneous parametric down-conversion in doped nonlinear crystals at low temperatures, which would be useful for combining heralded single-photon sources and quantum memories, is studied theoretically. The ordinary refractive index of a lithium niobate crystal doped with magnesium oxide LiNbO3:MgO is measured at liquid nitrogen and helium temperatures. On the basis of the experimental data, the coefficients of the Sellmeier equation are determined for the temperatures from 5 to 300 K. In addition, a poling period of the nonlinear crystal has been calculated for observing type-0 spontaneous parametric down-conversion (ooo-synchronism) at the liquid helium temperature under pumping at the wavelength of λp = 532 nm and emission of the signal field at the wavelength of λs = 794 nm, which corresponds to the resonant absorption line of Tm3+ doped ions.

DOI: 10.1051/epjconf/201716102002

Related papers

Degenerate photons from a cryogenic spontaneous parametric down-conversion source

Nina Amelie Lange, Timon Schapeler, Jan Philipp Höpker +2 more

We demonstrate the generation of degenerate photon pairs from spontaneous parametric down-conversion in titanium-indiffused waveguides in lithium niobate at cryogenic temperatures. Since the phase matching cannot be temperature tuned inside a cryostat, we rely on a precise empirical model of the refractive indices when fabricating a fixed poling period. We design the phase-matching properties of our periodic poling to enable signal and idler photons at $1559.3(6)$ nm and characterize the indistinguishability of our photons by performing a Hong-Ou-Mandel interference measurement. Despite the effects of photorefraction and pyroelectricity, which can locally alter the phase matching, we achieve cryogenic indistinguishable photons within 1.5 nm of our design wavelength. Our results verify sufficient understanding and control of the cryogenic nonlinear process, which has wider implications when combining quasi-phase-matched nonlinear optical processes with other cryogenic photonic quantum technologies, such as superconducting detectors.

Physical Review A•Aug 1, 2023•8 citations

Polling period and temperature dependence of lithium niobate on tunability of biphoton generation

Krishna Yadav, Balakrishnan Viswanathan, Prem Ballabh Bisht

Biphoton generation with spontaneous parametric down conversion (SPDC) process has applications in quantum imaging and sensing. Simulations have been done on periodically poled lithium niobate (PPLN) crystals with varying polled period. The poled period has been varied from 20.6$\mu \mathbf{m}$to 23.3$\mu \mathbf{m}$. The pump wavelengths have been selected in the range of 750 to 850 nm. The variations in temperature and the poled grating facilitate the generation of tunable entangled photon pairs from 1100 nm to 3200 nm.

International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)•Sep 23, 2024•0 citations

Preparation of single-photon states via cavity-assisted spontaneous parametric down-conversion for quantum memory based on Y7LiF4:Nd3+ crystal

D O Akat’ev, Латыпов Ильнур Зиннурович, Andrey V. Shkalikov +1 more

We report on the realization of a tunable single-photon source compatible with quantum memories based on isotopically pure Y7LiF4 crystals doped with Nd3+ ions. The source is based on spontaneous parametric down-conversion in a PPLN crystal placed in a resonator. The latter is formed by two mirrors which are transparent for the pump (532 nm) and idler (1377 nm) fields but high reflective for the signal field (867 nm). The width of the second-order cross-correlation function between the signal and idler photons is determined to be 1.5 ns for the cavity length of 8 cm, which corresponds to a cavity bandwidth of 100 MHz.

EPJ Web of Conferences•Jan 1, 2017•1 citation

Characterization of type-II spontaneous parametric down-conversion in domain-engineered PPLN

Paulina S. Kuo, Thomas Gerrits, Varun Boehm Verma +4 more

We characterize spontaneous parametric downconversion in a domain-engineered, type-II periodically poled lithium niobate (PPLN) crystal using seeded emission and single-photon techniques. Using continuous-wave (CW) pumping at 775 nm wavelength, the signal and idler are at 1532.5 nm and 1567.5 nm, respectively. The domain-engineered crystal simultaneously phasematches signal and idler pairs: [H(1532.5 nm), V(1567.5 nm)] and [V(1532.5 nm), H(1567.5 nm)]. We observe the tuning curves of these processes through difference-frequency generation and through CW fiber-assisted, single-photon spectroscopy. These measurements indicate good matching in amplitude and bandwidth of the two processes and that the crystal can in principle be used effectively to generate polarization-entangled photon pairs.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 16, 2016•10 citations

System of a Quantum Memory in a 143Nd:Y7LiF4 Crystal and a Matching Single-Photon Source Based on Spontaneous Parametric Down-Conversion

Ахмеджанов Ринат Абдулхаевич, Л. А. Гущин, I. V. Zelensky +4 more

The storage of a signal of a single-photon source based on spontaneous parametric down-conversion in a periodically poled MgO:PPLN crystal in a quantum memory based on an atomic frequency comb in an isotopically pure $$^{{{\text{143}}}}{\text{Nd}}{\kern 1pt} {\text{:}}{\kern 1pt} {{{\text{Y}}}^{{\text{7}}}}{\text{Li}}{{{\text{F}}}_{{\text{4}}}}$$ crystal has been demonstrated.

Journal of Experimental and Theoretical Physics Letters•Jun 1, 2025•0 citations

PPLN-based photon-pair source compatible with solid state quantum memories and telecom optical fibers

Латыпов Ильнур Зиннурович, A. V. Shkalikov, D O Akat’ev +1 more

We report on the realization of a tunable source of correlated photon pairs compatible with telecommunication networks and quantum memories involving dielectric crystals doped by Nd 3+ ions. The source is based on spontaneous parametric down-conversion in a 25 mm periodically poled lithium niobate crystal pumped by 532 nm cw laser. Spectral and correlation characteristics of the corresponding heralded single-photon source compatible with quantum memories are presented.

Journal of Physics Conference Series•Jun 1, 2017•2 citations

The possibility of observing spontaneous parametric down-conversion in doped nonlinear crystals at low temperatures, which would be useful for combining heralded single-photon sources and quantum memories, is studied theoretically. The ordinary refractive index of a lithium niobate crystal doped with magnesium oxide LiNbO3:MgO is measured at liquid nitrogen and helium temperatures. On the basis of the experimental data, the coefficients of the Sellmeier equation are determined for the temperatures from 5 to 300 K. In addition, a poling period of the nonlinear crystal has been calculated for observing type-0 spontaneous parametric down-conversion (ooo-synchronism) at the liquid helium temperature under pumping at the wavelength of λp = 532 nm and emission of the signal field at the wavelength of λs = 794 nm, which corresponds to the resonant absorption line of Tm3+ doped ions.

We demonstrate the generation of degenerate photon pairs from spontaneous parametric down-conversion in titanium-indiffused waveguides in lithium niobate at cryogenic temperatures. Since the phase matching cannot be temperature tuned inside a cryostat, we rely on a precise empirical model of the refractive indices when fabricating a fixed poling period. We design the phase-matching properties of our periodic poling to enable signal and idler photons at

1559.3(6)

nm and characterize the indistinguishability of our photons by performing a Hong-Ou-Mandel interference measurement. Despite the effects of photorefraction and pyroelectricity, which can locally alter the phase matching, we achieve cryogenic indistinguishable photons within 1.5 nm of our design wavelength. Our results verify sufficient understanding and control of the cryogenic nonlinear process, which has wider implications when combining quasi-phase-matched nonlinear optical processes with other cryogenic photonic quantum technologies, such as superconducting detectors.

Biphoton generation with spontaneous parametric down conversion (SPDC) process has applications in quantum imaging and sensing. Simulations have been done on periodically poled lithium niobate (PPLN) crystals with varying polled period. The poled period has been varied from 20.6

\mu \mathbf{m}

to 23.3

\mu \mathbf{m}

. The pump wavelengths have been selected in the range of 750 to 850 nm. The variations in temperature and the poled grating facilitate the generation of tunable entangled photon pairs from 1100 nm to 3200 nm.

We report on the realization of a tunable single-photon source compatible with quantum memories based on isotopically pure Y7LiF4 crystals doped with Nd3+ ions. The source is based on spontaneous parametric down-conversion in a PPLN crystal placed in a resonator. The latter is formed by two mirrors which are transparent for the pump (532 nm) and idler (1377 nm) fields but high reflective for the signal field (867 nm). The width of the second-order cross-correlation function between the signal and idler photons is determined to be 1.5 ns for the cavity length of 8 cm, which corresponds to a cavity bandwidth of 100 MHz.

We characterize spontaneous parametric downconversion in a domain-engineered, type-II periodically poled lithium niobate (PPLN) crystal using seeded emission and single-photon techniques. Using continuous-wave (CW) pumping at 775 nm wavelength, the signal and idler are at 1532.5 nm and 1567.5 nm, respectively. The domain-engineered crystal simultaneously phasematches signal and idler pairs: [H(1532.5 nm), V(1567.5 nm)] and [V(1532.5 nm), H(1567.5 nm)]. We observe the tuning curves of these processes through difference-frequency generation and through CW fiber-assisted, single-photon spectroscopy. These measurements indicate good matching in amplitude and bandwidth of the two processes and that the crystal can in principle be used effectively to generate polarization-entangled photon pairs.

The storage of a signal of a single-photon source based on spontaneous parametric down-conversion in a periodically poled MgO:PPLN crystal in a quantum memory based on an atomic frequency comb in an isotopically pure

^{{{\text{143}}}}{\text{Nd}}{\kern 1pt} {\text{:}}{\kern 1pt} {{{\text{Y}}}^{{\text{7}}}}{\text{Li}}{{{\text{F}}}_{{\text{4}}}}

crystal has been demonstrated.