Symmetric Bidirectional Quantum Teleportation using a Six-Qubit Cluster State as a Quantum Channel

Bidirectional quantum teleportation is a fundamental protocol for exchanging quantum information between two quantum nodes. All bidirectional quantum teleportation protocols till now have achieved a maximum efficiency of $40\%$. Here, we propose a new scheme for symmetric bidirectional quantum teleportation using a six-qubit cluster state as the quantum channel, for symmetric ($3\leftrightarrow3$) qubit bidirectional quantum teleportation of a special three-qubit entangled state. The novelty of our scheme lies in its generalization for ($N\leftrightarrow N$) qubit bidirectional quantum teleportation employing a $2N$-qubit cluster state. The efficiency of the proposed protocol is remarkably increased to $50\%$ which is highest till now. Interestingly, only GHZ-state measurements and four Toffoli-gate operations are necessary which is independent of the number $(N)$ of qubits to be teleported.