Fast multi-copy entanglement purification with linear optics

Abstract

Fast multi-copy entanglement purification with linear optics * Cai Chun(蔡 春) a)c) , Zhou Lan(周 澜) a)b) , and Sheng Yu-Bo(盛宇波) a)c) † a)

Photonic hybrid state entanglement swapping using cat state superpositions

“…From figures 3 to 5, we can conclude that we do not desire an averaged loss mismatch value of Υ > 0.10, as this gives an unacceptably low fidelity (F ≤ 0.80) for all α. We consider an acceptable fidelity result to be F ≥ 0.80, as we could use any of the multitude of entanglement purification protocols available [62][63][64][65][66] to increase this fidelity to a sufficient level for further quantum communication/computation uses (i.e. to F ≥ 0.95).…”

“…Research into increasing the level of entanglement shared between two distant parties has been carried out extensively, and there exist a multitude of potential protocols which can increase Bell state fidelity from F = 0.60 to F ≥ 0.95 [62][63][64][65][66]. Of course, in this circumstance this then requires one to use a higher number of lower fidelity pairs to produce one very high fidelity pair, although we argue that for the intended purpose of this protocol it is logical to sacrifice high bit rates to ensure that the entangled pairs delivered are of the best quality.…”

Photonic Hybrid State Entanglement Swapping using Cat State Superpositions

“…7, 8 and 9, we can conclude that we do not desire an averaged loss mismatch value of Υ > 0.10, as this gives an unacceptably low fidelity (F ≤ 0.80) for all α. We consider an acceptable fidelity result to be F ≥ 0.80, as we could use any of the multitude of entanglement purification protocols available [61][62][63][64][65] to increase this fidelity to a sufficient level for further quantum communication/computation uses (i.e. to F ≥ 0.95).…”

“…Research into increasing the level of entanglement shared between two distant parties has been carried out extensively, and there exist a multitude of potential protocols which can increase Bell state fidelity from F = 0.60 to F ≥ 0.95 [61][62][63][64][65]. Of course, in this circumstance this then requires one to use a higher number of lower fidelity pairs to produce one very high fidelity pair, although we argue that for the intended purpose of this protocol it is logical to sacrifice high bit rates to ensure that the entangled pairs delivered are of the best quality.…”

Multi-copy entanglement purification with practical spontaneous parametric down conversion sources

“…[19,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] The third group is to use the multi-copy degraded mixed states. [45][46][47][48][49][50] In the third group, they usually exploit the controlled-not (CNOT) gates and controlled-controlled-not (CCNOT) gates to complete the purification. However, CNOT and CCNOT are not feasible in current experimental condition, which makes this kind of protocols be far away from current application.…”