  We propose a new avenue towards distillation of quantum entanglement that is
implemented by directly passing the entangled qubits through a mode-matched
filter. This approach can be applied to a common class of entanglement
impurities appearing in photonic systems where the impurities inherently occupy
different spatiotemporal modes than the entangled qubits. As a specific
application, we show that our method can be used to significantly purify the
telecom-band entanglement generated via the Kerr nonlinearity in single-mode
fibers where a substantial amount of Raman-scattering noise is concomitantly
produced.

Quantum Physics