Quantum entanglement, a fundamental property ensuring security of key distribution and efficiency of quantum computing, is extremely sensitive to decoherence. Different procedures have been developed in order to recover entanglement after propagation over a noisy channel. However, besides a certain amount of noise, entanglement is completely lost. In this case the channel is called entanglement breaking and any multi-copy distillation methods cannot help to restore even a bit of entanglement. We report the experimental realization of a new method which restores entanglement from a single photon entanglement breaking channel. The method based on measurement of environmental light and quantum feed-forward correction can reveal entanglement even if this one completely disappeared. This protocol provides new elements to overcome decoherence effects.
Download