Teleporting two-qubit entanglement across 19 qubits on a superconducting quantum computer

TL;DR

This study demonstrates the teleportation of two-qubit entanglement across 19 qubits on a superconducting quantum computer, comparing different teleportation methods and optimizing paths based on entanglement measures.

Contribution

It introduces and evaluates two approaches for long-range entanglement teleportation on a large quantum device, highlighting the effectiveness of negativity-based path selection.

Findings

Entanglement is preserved after 19 hops using post-selection.

Dynamic circuit corrections enable 17 hops of entanglement.

Negativity maps outperform gate error maps for circuit compilation.

Abstract

Quantum teleportation is not merely a fascinating corollary of quantum entanglement, it also finds utility in quantum processing and circuit compilation. In this paper, we measure and track the entanglement and fidelity of two-qubit states prepared on a 127-qubit IBM Quantum device, as one of the qubits is teleported across 19 qubits. We design, evaluate and compare two distinct approaches to teleportation: post-selected measurement categorisation and dynamic circuit corrections based on mid-circuit measurements, and compare with direct state transportation using SWAP gates. By optimally choosing the teleportation path which exhibits the highest total negativity entanglement measure across nearest-neighbour pairs, we show the entanglement of a two-qubit graph state is sustained after at least 19 hops in teleportation using the post-selection approach and 17 hops using the dynamic circuit approach. We observe a higher level of teleported entanglement in paths determined from two-qubit negativities compared to those obtained from gate errors, demonstrating an advantage in using the negativity map over the gate error map for compiling quantum circuits.