Quantum Telecloning on NISQ Computers

Due to the no-cloning theorem, generating perfect quantum clones of an arbitrary quantum state is not possible, however approximate quantum clones can be constructed. Quantum telecloning is a protocol that originates from a combination of quantum teleportation and quantum cloning. Here we present $1 \rightarrow 2$ and $1 \rightarrow 3$ quantum telecloning circuits, with and without ancilla, that are theoretically optimal (meaning the clones are the highest fidelity allowed by quantum mechanics), universal (meaning the clone fidelity is independent of the state being cloned), and symmetric (meaning the clones all have the same fidelity). We implement these circuits on gate model IBMQ and Quantinuum NISQ hardware and quantify the clone fidelities using parallel single qubit state tomography. Quantum telecloning using mid-circuit measurement with real time if statements is demonstrated on the Quantinuum H1-2 device. Two alternative implementations of quantum telecloning (deferred measurement and post selection) are demonstrated on ibmq\_montreal for cases where mid-circuit measurement with real time if statements are not available. Our results show that NISQ devices can achieve near-optimal quantum telecloning fidelity; for example the Quantinuum H1-2 device running the telecloning circuits without ancilla achieved a mean clone fidelity of $0.824$ for two clone circuits and $0.765$ for three clone circuits (the theoretical fidelity limits are $0.8\bar{33}$ for two clones and $0.\bar{77}$ for three clones). This demonstrates the viability of performing experimental analysis of quantum information networks and quantum cryptography protocols on NISQ computers.