Source-linked AI summary
Surface code quantum communication
Austin G. Fowler, David S. Wang, Charles D. Hill, Thaddeus D. Ladd, Rodney Van Meter, Lloyd C. L. Hollenberg
TL;DR
Existing repeater protocols rely on two-way classical communication, limiting long-distance quantum communication rates. This paper uses surface-code error correction to avoid that communication under sufficiently reliable Bell-pair conditions, achieving arbitrarily low error over arbitrary distances with logarithmic repeater resources.
Problem
Existing quantum-repeater protocols use two-way classical communication, causing communication rates to decrease polynomially with distance and limiting practical long-range transmission.
Method
The protocol applies surface-code quantum error correction across repeater-linked Bell pairs, using heralded successes and error correction to handle link errors and loss.
Results
With heralded success probability S_B >∼ 0.65 and fidelity F >∼ 0.96, two-way classical communication is avoided, while arbitrarily low error over arbitrary distances requires only logarithmically increasing qubits per repeater.
Takeaways & Limitations
Surface-code repeaters can support long-range, high-fidelity quantum communication at a rate limited by local gate speed when Bell-pair generation is sufficiently reliable.
Abstract
from arXiv · showhide
Quantum communication typically involves a linear chain of repeater stations, each capable of reliable local quantum computation and connected to their nearest neighbors by unreliable communication links. The communication rate in existing protocols is low as two-way classical communication is used. We show that, if Bell pairs are generated between neighboring stations with a probability of heralded success greater than 0.65 and fidelity greater than 0.96, two-way classical communication can be entirely avoided and quantum information can be sent over arbitrary distances with arbitrarily low error at a rate limited only by the local gate speed. The number of qubits per repeater scales logarithmically with the communication distance. If the probability of heralded success is less than 0.65 and Bell pairs between neighboring stations with fidelity no less than 0.92 are generated only every T_B seconds, the logarithmic resource scaling remains and the communication rate through N links is proportional to 1/(T_B log^2 N).