Quantum Key Distribution via Charge Teleportation

We demonstrate that charge teleportation serves as a superior observable for Quantum Energy Teleportation (QET)-based cryptographic primitives. While following the LOCC protocol structure of earlier proposals, we show that decoding key bits via local charge rather than energy provides exact bit symmetry and enhanced robustness: by Local Operations and Classical Communication (LOCC) on an entangled many-body ground state, Alice’s one-bit choice steers the sign of a local charge shift at Bob, which directly encodes the key bit. Relative to energy teleportation schemes, the charge signal is bit-symmetric, measured in a single basis, and markedly more robust to realistic noise and model imperfections. We instantiate the protocol on transverse-field Ising models, star-coupled and one-dimensional chain, obtain closed-form results for two qubits, and for larger systems confirm performance via exact diagonalization, circuit-level simulations, and a proof-of-principle hardware run. We quantify resilience to classical bit flips and local quantum noise, identifying regimes where sign integrity, and hence key correctness, is preserved. These results position charge teleportation as a practical, low-rate QKD primitive compatible with near-term platforms.

💡 Research Summary

The paper introduces a novel quantum key distribution (QKD) primitive that leverages charge teleportation instead of the energy observable traditionally used in Quantum Energy Teleportation (QET)–based cryptographic schemes. By following the same Local Operations and Classical Communication (LOCC) framework as earlier QET proposals, the authors demonstrate that encoding key bits in the sign of a locally measured charge yields exact bit symmetry, requires measurement in a single basis, and exhibits markedly higher robustness against realistic noise and model imperfections.

The protocol begins with the preparation of a non‑degenerate ground state of a many‑body Hamiltonian shared between Alice (site 0) and Bob (site N). Alice performs a projective measurement on a Pauli operator σ_A (chosen from {X, Y}) and obtains outcome b∈{0,1}. She then decides whether to transmit the true outcome or its complement, encoded in a classical bit a∈{0,1}. The transmitted classical message is c = b⊕a together with the choice of σ_A. Bob, upon receiving (c, σ_A), applies a conditional rotation U_B(c, σ_B)=exp