Logic W‐state concentration with parity check

Abstract

Logic W state, which replaces each physical qubit in a W state with a Greenberger–Horne–Zeilinger state is robust against photon transmission loss in long‐distance quantum communication. In practical application, the environmental noise may make maximally entangled logic W state degrade to less entangled state, which largely limits its application. In this article, we propose an efficient entanglement concentration protocol (ECP) for logic W state, which can recover the less entangled logic W state into the maximally entangled logic W state. Our ECP relies on the nondemolition polarization parity check (PPC) gate constructed with cross‐Kerr nonlinearity. The distilled maximally entangled logic W state can be preserved for other application. Moreover, when the ECP fails, we can repeat the ECP to further concentrate the distilled less entangled logic W state. By repeating the ECP, the total success probability can be effectively increased. Based on above features, this ECP may be useful in quantum communication field.

Quantumness of Pure-State Ensembles via Coherence of Gram Matrix Based on Generalized α-z-Relative Rényi Entropy

“…It is more capable than entanglement [62,63] in that they can enable the secure transfer of information. It may also shed some light on understanding the nature of measurement in quantum mechanics [64,65].…”

Perfect NOT and conjugate transformations

“…The use of parity-check measurement is used in concentration of W-state in ref. [20]. Of course, unitary operation and measurement are extensively used in quantum key distribution [21].…”

Generalized uncertainty relations for multiple measurements

“…( 3) becomes H R H S S A log 2 c R, S , which yields a tighter bound due to S A 0. As far as the QMA-EUR is concerned, it can be applied to a number of quantum tasks [12][13][14][15][16][17][18] including quantum teleportation [12], quantum key distribution [13], entanglement witness [9], quantum metrology [14,15], quantum steering [16] and so forth. Additionally, some promising improvements had been made on QMA-EUR [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”