  A new quantum communication scheme is introduced which is the quantum
realization of the classical Kish-Sethuraman (KS) cipher. First the message is
bounced back with additional encryption by the Receiver and the original
encryption is removed and the message is resent by the Sender. The mechanical
analogy of this operation is using two padlocks; one by the Sender and one by
the Receiver. We show that the rotation of the polarization is an operator
which satisfies the conditions required for the KS encryption operators
provided single photons are communicated. The new method is not only simple but
has several advantages. The Evasdropper extracts zero information even if she
executes a quantum measurement on the state. The communication can be done by
two publicly agreed orthogonal states. Therefore, there is no inherent
detection noise. No classical channel and no entangled states are required for
the communication.

Quantum Physics