Abstract
We present a pulsed and integrated, highly non-degenerate parametric down-conversion (PDC) source of heralded single photons at telecom wavelengths, paired with heralding photons around 800 nm. The active PDC section is combined with a passive, integrated wavelength division demultiplexer on-chip, which allows for the spatial separation of signal and idler photons with efficiencies of more than 96.5%, as well as with multi-band reflection and anti-reflection coatings which facilitate low incoupling losses and a pump suppression at the output of the device of more than 99%. Our device is capable of preparing single photons with efficiencies of 60% with a coincidences-to-accidentals ratio exceeding 7400. Likewise, it shows practically no significant background noise compared to continuous wave realizations. For low pump powers, we measure a conditioned second-order correlation function of g(2) = 3.8 × 10−3, which proves almost pure single-photon generation. In addition, our source can feature a high brightness of 〈npulse〉 = 0.24 generated photon pairs per pump pulse at pump power levels below 100 μW. The high quality of the pulsed PDC process in conjunction with the integration of highly efficient passive elements makes our device a promising candidate for future quantum networking applications, where an efficient miniaturization plays a crucial role.
Highlights
Recent progress in the field of quantum information processing has highlighted the prospects of using integrated optic devices for quantum applications [1, 2, 3, 4, 5]
The active parametric downconversion (PDC) section is combined with a passive, integrated wavelength division demultiplexer on-chip, which allows for the spatial separation of signal and idler photons with efficiencies of more than 96.5%, as well as with multi-band reflection and anti-reflection coatings which facilitate low incoupling losses and a pump suppression at the output of the device of more than 99%
In this paper we report on the fabrication and analysis of an integrated type-I PDC source in titanium-indiffused periodically poled Z-cut lithium niobate waveguides (Ti:PPLN) for heralded single photons
Summary
Recent progress in the field of quantum information processing has highlighted the prospects of using integrated optic devices for quantum applications [1, 2, 3, 4, 5]. Integrated quantum photonics offers several advantages in comparison to free-space experimental setups with bulk optic components [6]. In 2008 Politi and co-workers [7] have demonstrated the first quantum interference and photonic gates on-chip, while different groups have developed sophisticated and integrated experiments with two-photon interference [8, 9] or photon-entanglement [10, 11], controlled qubit-operations [12] as well as controlled phase shifts in linear optical circuits [5, 13]. In 2012 Metcalf et al have realized the first three-photon experiment inside a linear optical network [14] and recent research on Boson sampling in an integrated device demonstrates four-photon quantum interference[15]. The efficient coupling between these sources and the integrated circuit remains one bottleneck for designing systems with increasing complexity
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