Economical quantum secure direct communication network with single photons

In this paper a scheme for quantum secure direct communication(QSDC) network is proposed with a sequence of polarized singlephotons. The single photons are prepared originally in the samestate $vert 0rangle$ by the servers on the network, which willreduce the difficulty for the legitimate users to checkeavesdropping largely. The users code the information on the singlephotons with two unitary operations which do not change theirmeasuring bases. Some decoy photons, which are produced by operatingthe sample photons with a Hadamard, are used for preventing apotentially dishonest server from eavesdropping the quantum linesfreely. This scheme is an economical one as it is the easiest wayfor QSDC network communication securely.