Quantum transfer of interacting and entangled qubits

The transfer of quantum information between different locations is key to many quantum information processing tasks. Whereas, the transfer of a single qubit state has been extensively investigated, the transfer of a many-body system configuration has insofar remained elusive. We address the problem of transferring the state of n interacting qubits [1]. Both the exponentially increasing Hilbert space dimension, and the presence of interactions significantly scale-up the complexity of achieving high-fidelity transfer. By employing tools from random matrix theory and using the formalism of quantum dynamical maps, we derive a general expression for the average and the variance of the fidelity of an arbitrary quantum state transfer protocol for n interacting qubits. We find that the average fidelity decreases with the amount and the type of entanglement in the sender state [2]. Finally, by adopting a weak-coupling scheme in a spin chain, we obtain the explicit conditions for high-fidelity transfer of 3 and 4 interacting qubits.
[1] Tony J G Apollaro et al, Quantum transfer of interacting qubits, 2022 New J. Phys. 24 083025
https://iopscience.iop.org/article/10.1088/1367-2630/ac86e7
[2] Tony J G Apollaro et al, Entangled States Are Harder to Transfer than Product States, Entropy 2023, 25(1), > 46;
https://doi.org/10.3390/e25010046