The ten experiments
Announced 23 February 2022 · DRDO × IIT Delhi
The first intercity quantum link
How it works
Quantum key distribution encodes encryption keys into single photons, so any interception
disturbs them and is detected. The DRDO–IIT Delhi team ran QKD between Prayagraj and
Vindhyachal over more than 100 km of commercial-grade optical fiber already
deployed in the field, reaching sifted key rates up to 10 kHz — within reported international
standards.
Why it matters
The first proof that military-grade quantum keys could travel city to city on ordinary fiber.
The official announcement said the purpose was "bootstrapping military grade communication
security key hierarchy" — the key-management backbone Indian defence networks would run on.
Distance: >100 km · Sifted key rate: up to 10 kHz · Fiber: commercial-grade, field-deployed
Announced 6 October 2023 · IIT Delhi (Kanseri group)
380 km with no trusted nodes
How it works
In differential-phase-shift QKD, each key bit is encoded in the phase difference
between consecutive laser pulses rather than in single photons; the receiver interferes each
pulse with its neighbour, and the brightness of the interference reveals the bit. By optimising
the laser's steadiness, detector noise and fiber dispersion, Prof. Bhaskar Kanseri's team kept
errors below 2.5% after 380 km of standard telecom fiber — published in
Nature Scientific Reports and claimed as a world first for this protocol at that
distance.
Why it matters
It removes intermediate "trusted nodes" — relay points that must be trusted not to leak the
key, and are security weak points. A trusted-node-free link is what quantum-safe banking and
strategic communication between states actually need.
Distance: 380 km · QBER: <2.5% · No trusted nodes · Team: Kanseri, Pathak, Chaudhary, Sangeeta
16 June 2025 · DRDO × IIT Delhi (DIA-CoE)
Quantum keys through open air
How it works
A source creates pairs of photons whose polarisations are entangled — measuring one
instantly fixes the other. One photon of each pair flies through open air to each party; both
measure their photons, and matching measurements become secret key bits. The IIT Delhi campus
link achieved ~240 secure bits per second with errors below 7% over more than
a kilometre of free space. Any eavesdropper trying to peek breaks the entanglement, showing up
as errors — so interception is detected, not just resisted.
Why it matters
Cable-free military links for battlefields, remote terrain and cities where fiber cannot be
laid — and a stepping stone to ground-to-satellite quantum links. Defence Minister Rajnath
Singh called it a "game changer in future warfare".
Distance: >1 km free space · Key rate: ~240 bps · QBER: <7% · Project: DRDO Directorate of Futuristic Technology Management
Announced 29 December 2020 · DRDO DYSL-QT
Randomness you can trust
How it works
A single photon hits a 50/50 beam splitter — quantum physics says it goes left or right with
no pattern whatsoever, unlike computer-generated "pseudo-random" numbers that are
secretly predictable. Each choice becomes a 0 or 1, yielding ~150,000 genuinely
unpredictable bits per second. The device passed the global NIST and Die-harder
randomness test suites, and was independently verified with DRDO's own indigenous test suite.
Why it matters
True randomness feeds key generation, key wrapping and authentication in military
cryptography. Predictable randomness would be a fatal flaw in an adversary's hands — this
closes it with sovereign hardware.
Speed: ~150 kbps after post-processing · Certified: NIST + Die-harder + DRDO SAG suite
Announced August 2024 · DYSL-QT × TIFR × TCS
India's 6-qubit processor
How it works
Tiny superconducting circuits cooled near absolute zero behave as qubits — they can be 0, 1, or
both at once. TIFR designed and fabricated a novel ring-resonator architecture
to link six of them; DYSL-QT scientists assembled the control and measurement electronics; TCS
built the cloud interface. The full loop was tested: submit a circuit over the cloud, execute
it on the hardware, read the results back — demonstrated before the DYSL-QT apex committee.
(The exact announcement day was not confirmed in the reports available.)
Why it matters
The first step toward India's own quantum computers for defence-grade optimisation and
research — running on Indian-designed hardware instead of depending on foreign machines.
Qubits: 6, superconducting · Architecture: in-house ring-resonator (TIFR Colaba) · Interface: TCS cloud
Announced July 2026 · DRDO × Taqbit Labs (Bengaluru)
Quantum keys meet the field
How it works
DRDO announced via its official channels that, with industry partner Taqbit Labs, it had
completed military field trials of a scalable, productised fibre-based QKD system
with a multi-hop architecture — moved beyond lab proof-of-concept into engineered, deployable
equipment. Exact dates and technical parameters were not published.
Why it matters
This is the transition from "it works in the lab" to "soldiers can use it" — the stated aim
is future-proofing India's strategic communication networks against quantum computers.
Taqbit separately signed a February 2026 agreement for quantum-safe satellite communications.
System: fibre-based QKD, multi-hop · Status: field trials completed (announced) · Parameters: not published
7 May 2025 · STL × C-DOT, at IIT Madras
Quantum security on ordinary telecom cable
How it works
One glass fiber can contain four cores — separate light-carrying channels.
Quantum key pulses travel down one core while ordinary internet data races down the other
three; the physical separation stops the bright classical signals from blinding the faint
quantum ones. Demonstrated over 100 km at the DoT-sponsored Advanced Optical Communications
Test Bed at IIT Madras.
Why it matters
No expensive dedicated "dark fiber" needed — quantum security can run inside the same cables
telecom companies already lay. That makes quantum-safe networks economically realistic for
5G/6G India.
Distance: 100 km · Fiber: 4-core multi-core · Quantum + classical data on the same cable
February–March 2021 · RRI × ISRO (QuEST)
Keys beamed between buildings
How it works
In February 2021, Prof. Urbasi Sinha's QuIC lab at RRI beamed entangled photons 50 m
between two buildings at night — darkness keeps sunlight from drowning out the faint
photon signal — India's first free-space entanglement-based QKD. In March 2021, ISRO's Space
Applications Centre went further: 300 m of open-air quantum communication,
using an indigenous NAVIC satellite receiver to synchronise transmitter and receiver clocks to
nanosecond precision and a compact gimbal to steer the beam — and they ran a live
video call secured by the quantum keys.
Why it matters
Proof that quantum keys can survive a trip through the atmosphere — the essential physics test
before satellites can beam keys down to Indian ground stations.
QuEST: 50 m, night, entanglement-based · ISRO SAC: 300 m, NAVIC time sync, live secured video call
25 November 2025 · IIT Bombay
Diamond compasses
How it works
A diamond with atomic "nitrogen-vacancy" defects acts as an atomic compass:
its electrons glow red under green light, and the glow shifts with magnetic fields — revealing
fields a billion times weaker than Earth's. Three indigenous platforms were demonstrated:
QMagPI, India's first portable quantum magnetometer; the Quantum
Diamond Microscope, a wide-field imager for nanoscale 3D magnetic imaging; and
Q-Confocal, which reads reactive-oxygen-species chemistry inside living cells
— a fingerprint of disease, demonstrated on glioblastoma cells.
Why it matters
Finding buried structures and mineral deposits, detecting submarines or hidden objects,
mapping neuron activity, label-free early cancer diagnostics, and finding defects in
semiconductor chips. The same visit inaugurated IIT Bombay's Liquid Helium Facility — over
95% gas recovery — enabling cryogenic quantum experiments.
Sensitivity: nanotesla range · Platforms: QMagPI, Quantum Diamond Microscope (PQuest Group), Q-Confocal
Announced 8 April 2026 · National Quantum Mission × QNu Labs
A 1,000 km quantum backbone
How it works
Special "decoy-state differential phase shift" pulses survive up to 200 km of ordinary
telecom fiber per hop without amplification; chaining five such links end to end
stretches secure key distribution to 1,000 km. Quantum keys and 10 Gbps
classical traffic share the same fiber. Described as one of the world's longest QKD
deployments, built to work in challenging terrain including underwater and underground
networks.
Why it matters
A national quantum-secure backbone for defence communications, banking networks and critical
infrastructure — the scale at which quantum security stops being a demo and becomes national
infrastructure.
Reach: 1,000 km · Per-hop: ~200 km on ordinary fiber · Quantum + 10 Gbps classical on one cable
Facts & figures
- Longest single-fiber demo
- 380 km, IIT Delhi DPS-QKD (Oct 2023)
- Longest quantum network
- 1,000 km, NQM + QNu Labs (Apr 2026)
- First free-space entanglement QKD
- 50 m, RRI–ISRO QuEST (Feb 2021)
- First intercity QKD
- >100 km, Prayagraj–Vindhyachal, up to 10 kHz sifted (Feb 2022)
- Free-space key rate
- ~240 bps, QBER <7%, IIT Delhi campus (Jun 2025)
- QRNG speed
- ~150 kbps, NIST + Die-harder certified (Dec 2020)
- Indigenous qubits
- 6, ring-resonator superconducting processor, DYSL-QT + TIFR + TCS (Aug 2024)
- Military field trials
- DRDO + Taqbit Labs, productised fibre QKD (Jul 2026)
- Quantum products unveiled
- 14, C-DOT 43rd Foundation Day (Aug 2026)
- Research centre
- DRDO Quantum Technology Research Centre, Metcalfe House, Delhi (May 2025)