Source-linked AI summary
Quantum communication without the necessity of quantum memories
W. J. Munro, A. M. Stephens, S. J. Devitt, K. A. Harrison, Kae Nemoto
TL;DR
The paper addresses quantum communication schemes that suffer from entanglement establishment, long-lived memory requirements, and photon loss. It proposes direct encoded transmission using redundant quantum parity codes, reporting high rates without long-lived memories but with sensitivity to local gate and measurement errors.
Problem
Existing quantum communication can require entangled links and long-lived memories, while channel, coupling, source, detector, and measurement losses degrade directly transmitted quantum states.
Method
The scheme directly transmits quantum information encoded with redundant quantum parity codes, transferring states between matter qubits and photons across successive network nodes.
Results
80 nodes can transmit quantum states over 800 km with success probability exceeding 98% using 80 × 200 matter qubits, while adjacent-node fidelity of 99.9% yields 90% overall fidelity.
Takeaways & Limitations
The scheme potentially enables communication rates several orders of magnitude faster than current schemes without long-lived quantum memories, provided accurate local gates are available.
Takeaways & Limitations
Without additional error correction, local gate and measurement errors limit the loss the parity code can tolerate and therefore how far quantum signals can be transmitted.
Abstract
from arXiv · showhide
Quantum physics is known to allow for completely new ways to create, manipulate and store information. Quantum communication - the ability to transmit quantum information - is a primitive necessary for any quantum internet. At its core, quantum communication generally requires the formation of entangled links between remote locations. The performance of these links is limited by the classical signaling time between such locations - necessitating the need for long lived quantum memories. Here we present the design of a communications network which neither requires the establishment of entanglement between remote locations nor the use of long-lived quantum memories. The rate at which quantum data can be transmitted along the network is only limited by the time required to perform efficient local gate operations. Our scheme thus potentially provides higher communications rates than previously thought possible.