A practical two-way system of quantum key distribution with untrusted source

The most severe problem of a two-way "plug-and-play" (p & p) quantum key distribution system is that the source can be controlled by the eavesdropper. This kind of source is defined as an üntrusted source". This paper discusses the effects of the fluctuation of internal transmittance on the final key generation rate and the transmission distance. The security of the standard BB84 protocol, one-decoy state protocol, and weak+vacuum decoy state protocol, with untrusted sources and the fluctuation of internal transmittance are studied. It is shown that the one-decoy state is sensitive to the statistical fluctuation but weak+vacuum decoy state is only slightly affected by the fluctuation. It is also shown that both the maximum secure transmission distance and final key generation rate are reduced when Alice's laboratory transmittance fluctuation is considered.     

ALMOST SURE GLOBAL WELL-POSEDNESS FOR THE FOURTH-ORDER NONLINEAR SCHR?DINGER EQUATION WITH LARGE INITIAL DATA

We consider the fourth-order nonlinear Schr?dinger equation(4NLS)(i?_t+εΔ+Δ²)u=c₁u^m+c₂(?u)u^m-1+c₃(?u)²u^m-2,and establish the conditional almost sure global well-posedness for random initial data in H^s(R^d) for s ∈(s_c-1/2,s_c],when d≥3 and m≥5,where s_c:=d/2-2/(m-1) is the scaling critical regularity of 4NLS with the second order derivative nonlinea...