A method for detecting eavesdropping while establishing secure communication channel between a local node and a remote node, the method comprising: generating, by the local node, a random key; generating a regular optical signal based on the random key; generating a quantum optical signal based on a control sequence and a set of quantum state bases; multiplexing the regular optical signal and the quantum optical signal to produce a hybrid optical signal; transmitting, over a quantum channel, the hybrid optical signal to the remote node; wherein the regular optical signal carries information associated with the random key for establishing the secure communication channel between the local node and the remote node; sending, over a classical channel, information associated with the control sequence and information associated with the set of quantum state bases to the remote node, wherein the information associated with the control sequence, comprises a length of the control sequence and bit values of the control sequence, and wherein the information associated with the set of quantum state bases comprises quantum-state-basis identifiers, QIDs, of the set of quantum state bases and length values corresponding to the QIDs; receiving an eavesdropping-detection result from the remote node based on measurement of the quantum optical signal included in the hybrid optical signal, the information associated with the control sequence, and the information associated with the set of quantum state bases; and in response to no eavesdropping being detected, establishing the secure communication channel between the local node and the remote node using the random key carried by the regular optical signal. generating, by the local node, a random key; generating a regular optical signal based on the random key; generating a quantum optical signal based on a control sequence and a set of quantum state bases; multiplexing the regular optical signal and the quantum optical signal to produce a hybrid optical signal; transmitting, over a quantum channel, the hybrid optical signal to the remote node; wherein the regular optical signal carries information associated with the random key for establishing the secure communication channel between the local node and the remote node; sending, over a classical channel, information associated with the control sequence and information associated with the set of quantum state bases to the remote node, wherein the information associated with the control sequence, comprises a length of the control sequence and bit values of the control sequence, and wherein the information associated with the set of quantum state bases comprises quantum-state-basis identifiers, QIDs, of the set of quantum state bases and length values corresponding to the QIDs; receiving an eavesdropping-detection result from the remote node based on measurement of the quantum optical signal included in the hybrid optical signal, the information associated with the control sequence, and the information associated with the set of quantum state bases; and in response to no eavesdropping being detected, establishing the secure communication channel between the local node and the remote node using the random key carried by the regular optical signal. <EOS>