Efficient and spectrally bright source of polarization-entangled photons

We demonstrate an efficient fiber-coupled source of nondegenerate polarization-entangled photons at 795 and 16090. 3em{0ex}nm using bidirectionally pumped parametric down-conversion in bulk periodically poled lithium niobate. The single-mode source has an inferred bandwidth of 500. 3em{0ex}GHz and a spectral brightness of 3000. 3em{0ex}pairs∕ (s0. 2em{0ex}GHz0. 2em{0ex}mW) of pump power that is suitable for narrowband applications such as entanglement transfer from photonic to atomic qubits.