Curator's Take
This research tackles one of quantum networking's most fundamental challenges: how to reliably create long-distance entanglement without requiring massive quantum devices or time-consuming multi-step protocols. The breakthrough here is achieving "one-shot" entanglement generation between arbitrarily distant qubits using only constant-sized quantum devices arranged in a 2D grid, with the clever insight that you only need the grid width to scale logarithmically with distance rather than linearly. This has immediate implications for both quantum repeater networks that could enable a quantum internet and large-scale quantum computers where maintaining entanglement across distant qubits on a chip becomes increasingly difficult. The fault-tolerant nature of the protocol, working below a constant noise threshold, makes this approach practically viable for real-world quantum systems where noise is unavoidable.
— Mark Eatherly
Summary
Consider a rectangular grid of qubits in 2D with single-qubit and nearest-neighbor two-qubit operations subject to local stochastic Pauli noise. At different length scales, this setup describes both a single quantum computing device with geometrically limited connectivity between qubits arranged on a disc, and planar networks composed of quantum repeater stations of constant size. We give a protocol which robustly generates entanglement between distant qubits in this setup. For noise below a constant threshold error strength, it generates a constant-fidelity Bell pair between qubits separated by an arbitrarily large distance $R$. To generate distance-$R$ entanglement, a rectangular grid of qubits of dimensions $Θ(R)\times Θ(\mathsf{poly}(\log R))$ suffices. Our protocol applies quantum operations in one shot, establishing a Bell state in a constant time up to a known Pauli correction. In contrast, existing entanglement generation protocols either require local quantum devices controlling a number of qubits growing with the targeted distance, or are not single-shot, i.e., have a distance-dependent execution time. The protocol leverages many-body entanglement in networks and provides the first example of a short-range entangled state in 2D with long-range localizable entanglement robust to local stochastic Pauli noise. As an immediate corollary, we construct a 2D-local stabilizer Hamiltonian whose Gibbs states possess long-range localizable entanglement at constant positive temperature.