Qubit teleportation between non-neighbouring nodes in a quantum network

Abstract

Future quantum internet applications will derive their power from the ability to share quantum information across the network1,2. Quantum teleportation allows for the reliable transfer of quantum information between distant nodes, even in the presence of highly lossy network connections3. Although many experimental demonstrations have been performed on different quantum network platforms4–10, moving beyond directly connected nodes has, so far, been hindered by the demanding requirements on the pre-shared remote entanglement, joint qubit readout and coherence times. Here we realize quantum teleportation between remote, non-neighbouring nodes in a quantum network. The network uses three optically connected nodes based on solid-state spin qubits. The teleporter is prepared by establishing remote entanglement on the two links, followed by entanglement swapping on the middle node and storage in a memory qubit. We demonstrate that, once successful preparation of the teleporter is heralded, arbitrary qubit states can be teleported with fidelity above the classical bound, even with unit efficiency. These results are enabled by key innovations in the qubit readout procedure, active memory qubit protection during entanglement generation and tailored heralding that reduces remote entanglement infidelities. Our work demonstrates a prime building block for future quantum networks and opens the door to exploring teleportation-based multi-node protocols and applications2,11–13.

Requirements for a processing-node quantum repeater on a real-world fiber grid

“…These correspond to the minimal improvements over state-of-the-art hardware parameters that enable meeting the targets. Specifically, we consider parameters measured for networked group-IV color centers (specifically, for NV centers in diamond) [20,[56][57][58][59][60][61][62] and ion traps [63]. We find that considerable improvements are needed even to bridge relatively modest distances, with our study also shining light on which parameters require significantly more improvement than others.…”

“…(1) NV centers are a prominent example of group-IV color centers for which significant data is available from quantum-networking experiments [20,[56][57][58][59][60]. Here, the color center's optically-active electronic spin is employed as a communication qubit.…”

“…The hardware parameters used in our models are based on quantum-networking experiments with NV centers (single-click [20,[58][59][60] and doubleclick [56,57]), and trapped ions (double-click [63]).…”

Quantifying NV-center Spectral Diffusion by Symmetry

“…The spectrally narrow, spin-dependent optical transitions of nitrogen vacancy (NV) centers in diamond have enabled them to become a leading platform for such applications. Significant advances, including entanglement of NV centers with photons [6], quantum interference of photons from distinct NV centers [7,8], and heralded entanglement of remote NV centers [9] have enabled landmark loophole-free tests of Bell's inequality [10,11], demonstration of a three node quantum network [12], and teleportation of a state across such a network [13] using NV centers. However, two challenges limit scalability for such quantum networking schemes that are reliant on frequency matched photon generation from distinct NV centers.…”

Diamond Integrated Quantum Photonics: A Review

“…Optically active spin-qubits in diamond have successfully been utilized in several proof-of-principle experiments targeted towards the integration of the above mentioned components to realize a quantum network [39]- [43]. Advances in spinphoton entanglement [44] paved the way for photon-mediated entanglement of remote qubits [45]- [47], culminating in the recent demonstration of a three-node quantum network [48], [49]. While these demonstrations have been fruitful, it is worth noting that parallel advances have been made with other experimental platforms including trapped atoms and ions [17], [50]- [54], superconducting resonators [55], [56], self-assembled quantum dots [57]- [59], and defect-based qubits in other wide-bandgap semiconductors and dielectrics [60]- [70].…”