Quantum Key Distribution via Charge Teleportation

TL;DR

This work proposes and analyzes Quantum Key Distribution via charge teleportation (QCT), a primitive that encodes key bits in the sign of a teleported local charge observable on a globally conserved quantity. By LOCC on entangled TFIM ground states, Alice’s bit choice ($a$) deterministically modulates Bob’s local charge outcome $\langle\Delta Q_B\rangle$, yielding a symmetric, single-basis readout that is robust to realistic noise. The study develops a general observable-teleportation framework, implements two TFIM Hamiltonians (star-coupled and nearest-neighbor), and provides closed-form two-qubit results with extensive numerical, Qiskit-circuit, and hardware validation. Results show charge teleportation offers improved symmetry, noise resilience, and scalability compared to energy teleportation, with practical implications for near-term QKD platforms and potential extensions to timing-enhanced (TQET) schemes.

Abstract

We introduce a quantum key distribution (QKD) primitive based on charge teleportation: 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.

Figures (51)

• Figure 1: $Q_B$ vs. $J$, for the star-coupled model $H^{(1)}$, with $h=1$ and $\sigma_A = X_0$.
• Figure 2: $Q_B$ vs. $J$, for the nearest-neighbors model $H^{(2)}$, with $h=1$ and $\sigma_A = X_0$.
• Figure 3: $Q_B$ vs. $J$, for the nearest-neighbors model $H^{(2)}$, with $h=1$ and $\sigma_A = Y_0$.
• Figure 4: Comparison of $Q_B$ vs. $J$ under $\sigma_A = X_0$ and $Y_0$.
• Figure 5: Quantum circuit used to extract Bob's charge expectation value in the charge teleportation protocol.