Entanglement-based linear-optical qubit amplifier
Evan Meyer-Scott, Marek Bula, Karol Bartkiewicz, Antonín Černoch, Jan Soubusta, Thomas D. Jennewein, Karel Lemr · Physical Review A · 2013
We propose a linear-optical scheme for an efficient amplification of a photonic qubit based on interaction of the signal mode with a pair of entangled ancillae. In contrast to a previous proposal for qubit amplifier by Gisin et al. [Phys Rev. Lett. 105, 070501 (2010)], the success probability of our device does not decrease asymptotically to zero with increasing gain. Moreover, we show how the device can be used to restore entanglement deteriorated by transmission over a lossy channel and calculate the secure key rate for device-independent quantum key distribution.