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MHz rate and efficient synchronous heralding of single photons at telecom wavelengths

Enrico Pomarico, Bruno Sanguinetti, Barbosa Dos Santos Guerreiro, Thiago, Rob Thew, Hugo Zbinden

Published Jan 1, 2012• 31 citations
OpenAlex

Abstract

We report on the realization of a synchronous source of heralded single photons at telecom wavelengths with MHz heralding rates and high heralding efficiency. This source is based on the generation of photon pairs at 810 and 1550 nm via Spontaneous Parametric Down Conversion (SPDC) in a 1 cm periodically poled lithium niobate (PPLN) crystal pumped by a 532 nm pulsed laser. As high rates are fundamental for multi-photon experiments, we show that single telecom photons can be announced at 4.4 MHz rate with 45% heralding efficiency. When we focus only on the optimization of the coupling of the heralded photon, the heralding efficiency can be increased up to 80%. Furthermore, we experimentally observe that group velocity mismatch inside long crystals pumped in a pulsed mode affects the spectrum of the emitted photons and their fibre coupling efficiency. The length of the crystal in this source has been chosen as a trade off between high brightness and high coupling efficiency.

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We report on the realization of a synchronous source of heralded single photons at telecom wavelengths with MHz heralding rates and high heralding efficiency. This source is based on the generation of photon pairs at 810 and 1550 nm via Spontaneous Parametric Down Conversion (SPDC) in a 1 cm periodically poled lithium niobate (PPLN) crystal pumped by a 532 nm pulsed laser. As high rates are fundamental for multi-photon experiments, we show that single telecom photons can be announced at 4.4 MHz rate with 45% heralding efficiency. When we focus only on the optimization of the coupling of the heralded photon, the heralding efficiency can be increased up to 80%. Furthermore, we experimentally observe that group velocity mismatch inside long crystals pumped in a pulsed mode affects the spectrum of the emitted photons and their fibre coupling efficiency. The length of the crystal in this source has been chosen as a trade off between high brightness and high coupling efficiency.

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Olivier Alibart, Sébastien Tanzilli, Daniel B. Ostrowsky +2 more

We report on a guided wave asynchronous heralded photon source based on the creation of non-degenerate photon pairs by spontaneous parametric down conversion in a Periodically Poled Lithium Niobate waveguide. We show that using the signal photon at 1310\nm as a trigger, a gated detection process permits announcing the arrival of single photons at 1550nm at the output of a single mode optical fiber with a high probability of 0.37. At the same time the multi-photon emission probability is reduced by a factor of 10 compared to poissonian light sources.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jul 7, 2005•6 citations
We report on the realization of a synchronous source of heralded single photons at telecom wavelengths with MHz heralding rates and high heralding efficiency. This source is based on the generation of photon pairs at 810 and 1550 nm via Spontaneous Parametric Down Conversion (SPDC) in a 1 cm periodically poled lithium niobate (PPLN) crystal pumped by a 532 nm pulsed laser. As high rates are fundamental for multi-photon experiments, we show that single telecom photons can be announced at 4.4 MHz rate with 45% heralding efficiency. When we focus only on the optimization of the coupling of the heralded photon, the heralding efficiency can be increased up to 80%. Furthermore, we experimentally observe that group velocity mismatch inside long crystals pumped in a pulsed mode affects the spectrum of the emitted photons and their fibre coupling efficiency. The length of the crystal in this source has been chosen as a trade off between high brightness and high coupling efficiency.
We report on the realization of a synchronous source of heralded single photons at telecom wavelengths with MHz heralding rates and high heralding efficiency. This source is based on the generation of photon pairs at 810 and 1550 nm via Spontaneous Parametric Down Conversion (SPDC) in a 1 cm periodically poled lithium niobate (PPLN) crystal pumped by a 532 nm pulsed laser. As high rates are fundamental for multi-photon experiments, we show that single telecom photons can be announced at 4.4 MHz rate with 45% heralding efficiency. When we focus only on the optimization of the coupling of the heralded photon, the heralding efficiency can be increased up to 80%. Furthermore, we experimentally observe that group velocity mismatch inside long crystals pumped in a pulsed mode affects the spectrum of the emitted photons and their fibre coupling efficiency. The length of the crystal in this source has been chosen as a trade off between high brightness and high coupling efficiency.
We report a fibre-integrated heralded single-photon source based on a commercial Zn-indiffused MgO:PPLN ridge waveguide operated in Type-0 degenerate spontaneous parametric down-conversion (SPDC). The device emits a broadband spectrum spanning approximately 70 nm across the telecom C-and L-bands, with an absolute brightness of 9.1×1099.1\times 10^{9}9.1×109 pairs/(s mW). After accounting for optical losses, we determine an internal heralding efficiency of 58(5)%. The source maintains high purity, exhibiting a coincidences-to-accidentals ratio exceeding 9×1049\times 10^{4}9×104 and a heralded second-order correlation of gh(2)(0)=(5.53±0.46)×10−4g_{\text{h}}^{(2)}(0) = (5.53 \pm 0.46)\times 10^{-4}gh(2)​(0)=(5.53±0.46)×10−4. Low multi-photon noise and broadband emission demonstrate the viability of such platforms for wavelength-multiplexed quantum networking.
We explore the feasibility of using high conversion-efficiency periodically-poled crystals to produce photon pairs for photon-counting detector calibrations at 1550 nm. The goal is the development of an appropriate parametric down-conversion (PDC) source at telecom wavelengths meeting the requirements of high-efficiency pair production and collection in single spectral and spatial modes (single-mode fibres). We propose a protocol to optimize the photon collection, noise levels and the uncertainty evaluation. This study ties together the results of our efforts to model the single-mode heralding efficiency of a two-photon PDC source and to estimate the heralding uncertainty of such a source.
We make a thorough analysis of heralded single photon sources regarding how factors such as the detector gate-period, the photon rates, the fiber coupling efficiencies, and the system losses affect the performance of the source. In the course of this we give a detailed description of how to determine fiber coupling efficiencies from experimentally measurable quantities. We show that asynchronous sources perform, under most conditions, better than synchronous sources with respect to multiphoton events, but only for nearly perfect coupling efficiencies. We apply the theory to an asynchronous source of heralded single photons based on spontaneous parametric downconversion in a periodically poled, bulk, KTiOPO4 crystal. The source generates light with highly non-degenerate wavelengths of 810 nm and 1550 nm, where the 810 nm photons are used to announce the presence of the 1550 nm photons inside a single-mode optical fiber. For our setup we find the probability of having a 1550 nm photon present in the single-mode fiber, as announced by the 810 nm photon, to be 48%. The probability of multiphoton events is strongly suppressed compared to a Poissonian light source, giving highly sub-Poisson photon statistics.
We demonstrate a miniaturized, scalable high rate, pulsed single-photon source in the telecom band obtained by heralding a spontaneous parametric downconversion source pumped with a highly tunable GHz repetition rate pulsed laser in an all-guided wave scheme. For developing this source, we first perform second harmonic generation of ultrashort pump pulses varying with GHz rate at the telecom wavelength. Our investigation demonstrates a trade-off between the spectral brightness and the single-photon purity of the heralded single-photon source by controlling the repetition rate of pump pulses. For a 5 GHz repetition rate, a periodically poled lithium niobate waveguide in type-0 configuration produces the highest spectral brightness ∼8.5×106pairs/s/mW/GHz. We quantify the single-photon purity using the second-order autocorrelation function g(2), which reaches the lowest value of ∼(3.4 ± 0.038) × 10−4 for 20 GHz repetition rate pulses, generating heralded single photons at 45 kHz rate. Our all-guided wave configuration offers easy integration and alignment, paving the way for developing scalable, integrable, tunable purity single-photon sources for quantum technology applications, such as quantum communication and quantum networks.
We report on a guided wave asynchronous heralded photon source based on the creation of non-degenerate photon pairs by spontaneous parametric down conversion in a Periodically Poled Lithium Niobate waveguide. We show that using the signal photon at 1310\nm as a trigger, a gated detection process permits announcing the arrival of single photons at 1550nm at the output of a single mode optical fiber with a high probability of 0.37. At the same time the multi-photon emission probability is reduced by a factor of 10 compared to poissonian light sources.