Quantum key distribution with two-qubit quantum codes.
We propose a prepare-and-measure scheme for quantum key distribution with two-qubit quantum codes. The protocol is unconditionally secure under all types of intercept-and-resend attack. Given the symmetric and independent errors to the transmitted qubits, our scheme can tolerate a bit of an error rate up to 26% in four-state protocol and 30% in six-state protocol, respectively. These values are higher than all currently known threshold values for the prepare-and-measure protocols. Moreover, we give a practically implementable linear optics realization for our scheme.
Imai Quantum Computation and Information Project, ERATO, Japan Science and Technology Agency, Daini Hongo White Building 201, 5-28-3 Hongo, Bunkyo, Tokyo 113-0033, Japan. wang@qci.jst.go.jp
Xiang-Bin
XB
Wang