High-Capacity and High-Efficient Deterministic Secure Quantum Communication Based on Four-Qubit W State

Abstract A novel high-capacity and high-efficient deterministic secure quantum communication protocol with four-qubit W states is proposed. By utilizing four kinds of unitary operations, the two legitimate users can directly transmit the secret messages based on the Bell measurements and some additional classical information. Analysis shows that our protocol has a high capacity as each W state can carry two bits of secret information, and has a high intrinsic efficiency because almost all the instances are useful. Moreover, this protocol is unconditionally secure and feasible with present-day technique.