Quantum Bidirectional Teleportation 2 ↔ 2 or 2 ↔ 3 Qubit Teleportation Protocol Via 6-Qubit Entangled State

In this paper, firstly we propose a new protocol for quantum bidirectional teleportation of two particles in a six-qubit entangled channel, which is based on GHZ measurement and unitary operation. Then, also based on the six-qubit entangled state channel, a protocol for quantum bidirectional teleportation of two-three particles is proposed. The protocol utilizes Toffoli gate to convert three-qubit states into two-qubit states and a single qubit, and the rest of the teleportation is the same as the first protocol. Finally, we introduce an auxiliary bit to restore the state of the sender. Both these proposed protocols are more efficient than others in the same situation, which will be compared at the end of the paper.