Experimental quantum teleportation of propagating microwaves

TL;DR

This paper demonstrates deterministic quantum teleportation of microwave states over macroscopic distances, advancing microwave quantum communication and enabling future quantum networks with superconducting circuits.

Contribution

First experimental realization of microwave quantum teleportation using superconducting circuits with high fidelity exceeding the no-cloning limit.

Findings

Teleportation fidelity of 0.689 ± 0.004 achieved

Teleportation successful for states with up to 1.1 photons

Distance of 42 cm over which teleportation was demonstrated

Abstract

The modern field of quantum communication thrives on promise to deliver efficient and unconditionally secure ways to exchange information by exploiting quantum laws of physics. Here, quantum teleportation stands out as an exemplary protocol allowing for the disembodied and safe transfer of unknown quantum states using quantum entanglement and classical communication as resources. The experimental feasibility of quantum teleportation with propagating waves, relevant to communication scenarios, has been demonstrated in various physical settings. However, an analogous implementation of quantum teleportation in the microwave domain was missing so far. At the same time, recent breakthroughs in quantum computation with superconducting circuits have triggered a demand for quantum communication between spatially separated superconducting processors operated at microwave frequencies. Here, we demonstrate a realization of deterministic quantum teleportation of coherent microwave states by exploiting two-mode squeezing and analog feedforward over macroscopic distances $d = 42\,$cm. We achieve teleportation fidelities $F = 0.689 \pm 0.004$ exceeding the no-cloning $F_\mathrm{nc} = 2/3$ threshold for coherent states with an average photon number of up to $n_\mathrm{d} = 1.1$. Our results provide a key ingredient for the teleportation-based quantum gate for modular quantum computing with superconducting circuits and establish a solid foundation for future microwave quantum local area networks.