Quantum Dialogue by Using Single Photons

We propose a quantum dialogue scheme using a batch of single photons.In the scheme,we encode the states of the single photons with the secret message by two different unitary operations,and select randomly a sufficiently large subset of photons from the batch to check eavesdropping,so,our scheme can resist the intercept-and-resend attack efficiently.In addition,our scheme is practical because it uses usingle photons instead of EPR pairs.The conclusion shows that the scheme is unconditionally secure.