Frequency-bin entanglement of ultra-narrow band non-degenerate photon pairs

Abstract

We demonstrate frequency-bin entanglement between ultra-narrowband photons generated by cavity enhanced spontaneous parametric down conversion. Our source generates photon pairs in widely non-degenerate discrete frequency modes, with one photon resonant with a quantum memory material based on praseodymium doped crystals and the other photon at telecom wavelengths. Correlations between the frequency modes are analyzed using phase modulators and narrowband filters before detection. We show high-visibility two photon interference between the frequency modes, allowing us to infer a coherent superposition of the modes. We develop a model describing the state that we create and use it to estimate optimal measurements to achieve a violation of the Clauser-Horne (CH) Bell inequality under realistic assumptions. With these settings we perform a Bell test and show a significant violation of the CH inequality, thus proving the entanglement of the photons. Finally we demonstrate the compatibility with a quantum memory material by using a spectral hole in the praseodymium (Pr) doped crystal as spectral filter for measuring highvisibility two-photon interference. This demonstrates the feasibility of combining frequency-bin entangled photon pairs with Pr-based solid state quantum memories.

Entangled Photon-Pair Sources based on three-wave mixing in bulk crystals

“…In resonators with corresponding dispersion properties, complex emission profiles with multiple resonances can also be realized, a so-called bi-photon frequency comb [125][126][127]. Such an approach was recently used to demonstrate frequency-bin entanglement [128]. Similar approaches have recently been demonstrated in micro-ring resonators in silica [129], aided by the great flexibility in engineering dispersion on this platform.…”

Complex Quantum State Generation and Coherent Control Based on Integrated Frequency Combs

“…Such quantum frequency comb source characteristics suggest their strong potential for non-classical technologies, and towards the scalable preparation and manipulation of complex states. Several multi-channel sources based on QFCs have thereby been demonstrated, among them combs of correlated photons [17], cross-polarized photon pairs [31], entangled photon pairs [9], [23], [32], multi-photon states [9], and frequency-bin entangled states [10], [11], [33].…”

Universal compressive tomography in the time-frequency domain

“…We shall first introduce the basic elements concerning the kinematic description of the electromagnetic field in the TF domain and the compressive state tomography applied to arbitrary near-coherent (low-rank) signal states encoded in this domain. After detailing the experimental techniques, we present a novel set of compressive tomography results for signals encoded in two broad classes of specral-temporal formats, namely the TF pulsed modes [24][25][26] that encode both temporal and spectral information, and frequency bins [27][28][29][30][31][32][33] that reflect solely the spectral content. These results show that compressive characterization of arbitrary optical states is feasible and achievable with only a meager number of measurement settings.…”