Qubit Teleportation and Transfer across Antiferromagnetic Spin Chains

We explore the capability of spin-$1/2$ chains to act as quantum channels for both teleportation and transfer of qubits. Exploiting the emergence of long-distance entanglement in low-dimensional systems [Phys. Rev. Lett. 96, 247206 (2006)], here we show how to obtain high communication fidelities between distant parties. An investigation of protocols of teleportation and state transfer is presented, in the realistic situation where temperature is included. Basing our setup on antiferromagnetic rotationally invariant systems, both protocols are represented by pure depolarizing channels. We propose a scheme where channel fidelity close to 1 can be achieved on very long chains at moderately small temperature.

Figure 1

Model Hamiltonian considered for teleportation (joint measure between $S$ and $A$) and for transfer (switching on $\gamma$ at a given time).

Figure 2

Finite-size scaling behavior of the lowest gaps. In the inset is plotted the scaling exponent fitted with the law $\Delta =c{L}^{-\alpha }$. The data were obtained with a DMRG code using 400–500 optimized states and three finite system sweeps.

Figure 3

Fidelity of teleportation between end sites $A$ and $B$ as a function of temperature for the Heisenberg model. The curves refer to different values of the interaction $J_p$.

Figure 4

Transfer fidelity at optimal time as a function of the chain length $L$. The curves refer to different values of the coupling $J_p$ between the probes ($A$ and $B$) and the chain. Results are reported at both zero and finite temperature.