Continuous-variable entanglement swapping

홍정식

Peter van Loock, Samuel L. Braunstein

We give a protocol and criteria for demonstrating unconditional teleportation of continuous-variable entanglement (i.e., entanglement swapping). The initial entangled states are produced with squeezed light and linear optics. We show that any nonzero entanglement (any nonzero squeezing) in both of two entanglement sources is sufficient for entanglement swapping to occur. In fact, realization of continuous-variable entanglement swapping is possible using only two single-mode squeezed states.

Anthony Short, Sandu Popescu, Nicolas Gisin

Jin‐Ming Liu, Bao‐Sen Shi, Xiao-Feng Fan +2 more

We discuss the continuous variable entanglement swapping using the Wigner function. The sufficient inseparability criterion for continuous variable systems is used to analyse the quantum correlation. Perfect teleportation can be obtained by increasing the degree of squeezing on the entanglement source. Entanglement swapping occurs for any nonzero squeezing in both of the two initial sources if optimal gain is obtained.

Kevin Marshall, Christian Weedbrook

We present a very brief overview of entanglement swapping as it relates to continuous-variable quantum information. The technical background required is discussed and the natural link to quantum teleportation is established before discussing the nature of Gaussian entanglement swapping. The limitations of Gaussian swapping are introduced, along with the general applications of swapping in the context of to quantum communication and entanglement distribution. In light of this, we briefly summarize a collection of entanglement swapping schemes which incorporate a non-Gaussian ingredient and the benefits of such schemes are noted. Finally, we motivate the need to further study and develop such schemes by highlighting requirements of a continuous-variable repeater.

Nathan L. Harshman