C-DOT and STL achieve India's first Quantum Key Distribution over multi-core fibre
C-DOT and Sterlite Technologies Ltd (STL) tested India's first Quantum Key Distribution (QKD) transmission over a 4-core multi-core fibre, establishing a stable link over more than 100 km, the Communications Ministry said on 17 April 2025.
Summary
The Centre for Development of Telematics (C-DOT), the telecom R&D centre of the Department of Telecommunications, and Sterlite Technologies Ltd (STL) have tested India's first QKD transmission over a 4-core Multi-Core Fibre (MCF), the Ministry of Communications said on 17 April 2025. Quantum signals were sent through one core while the other three cores carried high-speed user data, and a stable QKD link was established over a distance exceeding 100 km. QKD usually needs a dedicated dark fibre for the quantum channel; MCF allows quantum and classical signals to share one fibre in separate cores, saving fibre cost. C-DOT's QKD systems have received Technology Approval from the Telecommunication Engineering Centre (TEC).
Key facts
- Partners
- C-DOT (DoT) and Sterlite Technologies Ltd
- First
- India's first QKD over multi-core fibre
- Fibre
- 4-core MCF: 1 core quantum, 3 cores user data
- Distance
- Over 100 km
- Approval
- C-DOT QKD systems have TEC Technology Approval
Practice MCQs 2 questions
In the C-DOT–STL trial announced in April 2025, a stable Quantum Key Distribution link over multi-core fibre was established over a distance exceeding:
Show answer
Correct answer: D — 100 km
Over 100 km, with high-capacity classical data on the same fibre.
In India's first QKD over multi-core fibre (C-DOT and STL), how was the fibre used?
Show answer
Correct answer: C — 4-core fibre: one core quantum, three cores user data
A 4-core MCF was used: quantum signals in one core and high-speed user data in the other three.