India’s ‘Invisible’ Eyes Underwater: Can Quantum Tech Really Catch Submarines?

Key Highlights

✅ Revolutionary Detection: DRDO Chief Dr. Samir V. Kamat revealed India is developing quantum magnetometers capable of detecting submarines at 100-200 meter depths by sensing picotesla-level magnetic disturbances​​

✅ Quantum Tech Infrastructure: DRDO inaugurated the Quantum Technology Research Centre (QTRC) in May 2025, equipped with atomic magnetometers, quantum communication systems, and ultra-small atomic clocks​

✅ National Quantum Mission: India’s ₹6,003.65 crore quantum mission (2023-2031) aims to develop 50-1000 qubit quantum computers, 2000 km satellite-based secure communication, and ultra-sensitive magnetometers​

✅ Strategic Context: China operates the world’s largest navy with expanding submarine fleet in Indian Ocean, while Pakistan acquires eight advanced Hangor-class submarines from China by 2028​

✅ DRDO-IIT Breakthrough: June 2025 demonstration of quantum entanglement-based secure communication over 1+ km achieved 240 bps secure key rate, marking India’s entry into quantum era​

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When Silence Becomes a Weapon—And a Vulnerability

Imagine a nuclear-powered submarine gliding silently 200 meters beneath the Indian Ocean’s surface. No engine roar. No sonar ping. Just the ocean’s whisper masking a vessel carrying cruise missiles capable of striking targets hundreds of kilometers inland. Traditional detection systems scan desperately—acoustic sensors straining against the submarine’s noise-reduction technology, surface ships vulnerable to surprise attacks from below.

Now imagine an Indian P-8I Poseidon aircraft or UAV flying overhead, equipped not with conventional sonar but with quantum magnetometers—sensors so sensitive they detect the minute disturbances a submarine’s steel hull creates in Earth’s magnetic field. Disturbances measured in picoteslas (10⁻¹² Tesla)—changes a trillion times smaller than a refrigerator magnet’s pull. spslandforces​​

This isn’t science fiction. It’s India’s emerging reality.

In a revelation that sent ripples through defense circles, DRDO Chief Dr. Samir V. Kamat disclosed that India is actively developing quantum sensing technology for submarine detection—a capability that could fundamentally transform Anti-Submarine Warfare (ASW) in the Indo-Pacific.​​

“When a submarine moves underwater, its steel structure creates small changes in Earth’s magnetic field. These changes are very subtle, but if we have advanced sensors, they can be detected. DRDO is working on magnetometers that can detect changes at the picotesla level. This technology can be integrated onto aircraft or drones, enabling detection of submarines at depths of 100 to 200 meters,” Dr. Kamat explained.​​

For navigating questions on defense technology, maritime security, and strategic autonomy, understanding quantum sensing’s defense applications isn’t optional—it’s imperative for comprehensive answers on India’s evolving security architecture.

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The Quantum Advantage: Why This Changes Everything

Understanding Quantum Sensing Fundamentals

Quantum sensing exploits quantum mechanical phenomena—superposition, entanglement, and quantum interference—to achieve measurement precision impossible with classical sensors. pib.gov​

Core Principles:

Superposition: Quantum particles existing in multiple states simultaneously until measured, allowing sensors to detect multiple parameters concurrently

Entanglement: Particles remaining correlated regardless of distance, enabling distributed sensing networks

Quantum Interference: Minute environmental changes affecting quantum states, translating physical phenomena into measurable signals

Quantum magnetometers specifically leverage optically pumped magnetometry using alkali vapor cells (rubidium or cesium atoms). When magnetic fields affect these atoms’ energy levels, they generate detectable microwave resonance signals revealing field strength and direction.

How Submarine Detection Works

Submarines, constructed primarily from ferromagnetic steel, inevitably disturb Earth’s magnetic field as they move underwater. Traditional Magnetic Anomaly Detectors (MAD) on patrol aircraft can detect these disturbances, but their sensitivity and range remain limited. dras​​

Quantum magnetometers offer transformative advantages:

Picotesla Sensitivity: Detecting magnetic field changes at 10⁻¹² Tesla—orders of magnitude more sensitive than classical MAD systems​

Passive Detection: Unlike active sonar that broadcasts acoustic signals (alerting target submarines), quantum magnetic sensing remains completely passive—the submarine never knows it’s being tracked​

Acoustic Countermeasure Immunity: Modern submarines employ advanced noise reduction, anechoic coatings, and quiet propulsion defeating acoustic detection. Magnetic signatures cannot be silenced—steel remains steel​

Depth Penetration: Effective at 100-200 meter depths, covering the operational range where many diesel-electric and nuclear submarines patrol​​

Platform Flexibility: Mountable on maritime patrol aircraft (P-8I Poseidon), helicopters (MH-60R), and UAVs (MQ-9B), creating distributed aerial surveillance networks​​

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DRDO’s Quantum Ecosystem: Building Indigenous Capabilities

Quantum Technology Research Centre (QTRC)

On May 27, 2025, DRDO inaugurated the Quantum Technology Research Centre (QTRC) at Metcalfe House, Delhi—a dedicated facility propelling India’s quantum defense capabilities.​

Inaugurated by: Dr. Samir V. Kamat, Secretary Department of Defence R&D and Chairman DRDO

Key Capabilities:

Quantum Sensing Technologies:

• Atomic Magnetometer using optically pumped magnetometry for ultra-sensitive magnetic field detection (submarine detection application)​
• Ultra-Small Atomic Clock based on Coherent Population Trapping (CPT) for precision timekeeping in GNSS-denied environments (submarines, underground operations)​
• Quantum gravimeters for underground facility detection

Quantum Communications:

• Quantum Key Distribution (QKD) experimental platforms enabling ultra-secure communication
• Single-photon source testbeds
• Characterization setups for Vertical-Cavity Surface-Emitting Lasers (VCSELs) and Distributed Feedback Lasers​

Quantum Devices & Materials:

• Micro Fabricated Alkali Vapor Cell characterization
• Solid-state quantum devices and materials research​

Leading Institutions:

• Scientific Analysis Group (SAG), DRDO – Quantum communications
• Solid State Physics Laboratory (SSPL), DRDO – Foundational technologies​

National Quantum Mission: The Bigger Picture

QTRC operates within India’s ambitious National Quantum Mission (NQM), approved by the Union Cabinet on April 19, 2023, with a budget of ₹6,003.65 crore (2023-2031). indiascienceandtechnology​

Mission Objectives:

Quantum Computing:

• Develop intermediate-scale quantum computers with 50-1000 physical qubits using superconducting and photonic platforms​

Quantum Communication:

• Satellite-based secure quantum communication spanning 2000+ km within India and internationally
• Inter-city Quantum Key Distribution (QKD) over 2000 km
• Multi-node quantum networks with quantum memories​

Quantum Sensing & Metrology:

• Magnetometers with high sensitivity in atomic systems (defense submarine detection application)
• Atomic clocks for precision timing, communications, navigation
• Quantum gravimeters for resource exploration and underground detection​

Quantum Materials & Devices:

• Superconductors, novel semiconductor structures, topological materials
• Single-photon sources/detectors, entangled photon sources​

Four Thematic Hubs (T-Hubs) Established (September 2024):

• Quantum Computing Hub: IISc Bengaluru
• Quantum Communication Hub: IIT Madras & C-DOT Delhi
• Quantum Sensing & Metrology Hub: IIT Bombay
• Quantum Materials & Devices Hub: IIT Delhi​

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The Submarine Threat: Why India Needs Quantum ASW

Chinese Submarine Expansion in Indian Ocean

China operates the world’s largest navy with over 370 ships and submarines—surpassing the US Navy in sheer numbers. The People’s Liberation Army Navy (PLAN) submarine fleet includes:​

• Nuclear-powered attack submarines (SSN): Type 093 Shang-class, Type 095 (under development)
• Nuclear-powered ballistic missile submarines (SSBN): Type 094 Jin-class carrying JL-2 submarine-launched ballistic missiles
• Diesel-electric attack submarines: Type 039A/B Yuan-class with Air Independent Propulsion (AIP)​

Chinese submarines increasingly operate in the Indian Ocean Region (IOR)—India’s strategic backyard—visiting ports in Pakistan (Karachi), Sri Lanka (Colombo), and Djibouti as part of the “String of Pearls” strategy encircling India.​

Pakistan’s Submarine Modernization

Pakistan is acquiring eight advanced Hangor-class submarines from China—the largest arms export contract in Chinese military history worth $4-5 billion.​

Hangor-Class Specifications:

• Type: Diesel-electric attack submarine (export variant of Chinese Type 039A/B Yuan-class)
• Displacement: 2,800 tons (significantly larger than India’s 1,775-ton Kalvari-class)
• Length: 76 meters
• Propulsion: Four diesel engines + Air Independent Propulsion (AIP) system enabling extended underwater endurance
• Armament: Six 21-inch torpedo tubes, anti-ship missiles, Babur-3 subsonic cruise missiles (450 km range—potential nuclear delivery platform)​

Delivery Timeline:

• First four submarines: Built by China Shipbuilding & Offshore International Company (CSOC) in Wuhan; three already delivered (April 2024, March 2025, August 2025)​
• Remaining four submarines: Being built at Karachi Shipyard & Engineering Works under Transfer of Technology arrangement; delivery by 2028​

China has also supplied Pakistan with four modern naval frigates, over 600 VT-4 battle tanks, 36 J-10CE fighter jets, and the Rizwan spy ship—with over 81% of Pakistan’s arms coming from Beijing in the past five years according to SIPRI.​

Critical Sea Lanes at Risk

The Indian Ocean carries 80% of global oil trade—vital for India’s energy security. Key strategic chokepoints include:​

• Malacca Strait: 25% of traded goods, 25% of oil shipments pass through this narrow channel
• Arabian Sea: Energy corridors from Persian Gulf to India and East Asia
• Bay of Bengal: Trade routes connecting India with Southeast Asia​

Submarine threats to these sea lines of communication (SLOCs) could strangle India’s economy during conflict, making robust ASW capabilities existential imperatives.

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India’s Current ASW Architecture—And Its Gaps

Existing Capabilities

Aerial ASW Platforms:

P-8I Poseidon Maritime Patrol Aircraft:

• 12 aircraft in service (with additional units on order)
• Range: 1,200+ nautical miles with 4+ hours on-station endurance
• Sensors: APY-10 radar, Magnetic Anomaly Detector (MAD), Electro-Optical/Infrared (EO/IR) turret, sonobuoys
• Weapons: Torpedoes, depth charges, Harpoon anti-ship missiles​

MH-60R Romeo Helicopters:

• 24 helicopters inducted (procurement of additional units ongoing)
• Ship-launched ASW platform with dipping sonar, sonobuoys, torpedoes
• Complements P-8I by providing over-the-horizon surveillance for fleet operations​

Surface ASW Assets:

• Destroyers, frigates, corvettes equipped with hull-mounted and towed-array sonars
• Anti-submarine rockets (RBU-6000) and torpedoes​

Underwater Surveillance:

• Submarine Optical Fiber Cable (SOFC) network with hydrophones along coastline
• Advanced Underwater Sensor Network planned for large-scale Indian Ocean surveillance integrating acoustic, magnetic, gravitational, temperature sensors​

Critical Limitations

Acoustic Detection Constraints:

• Modern submarines’ noise reduction (anechoic coatings, quiet propulsion) drastically reduces acoustic signatures
• Sea state dependencies: Rough seas, thermal layers, and marine life create acoustic clutter
• Limited range: Passive sonar effective at 10-50 km; active sonar risks counter-detection​

Surveillance Coverage Gaps:

• Indian Ocean spans 70.56 million km²—India’s ASW assets provide limited coverage
• Persistent, wide-area maritime domain awareness requires distributed sensor networks​

Adversary Stealth Improvements:

• China’s Type 039B Yuan-class and Pakistan’s Hangor-class feature advanced AIP systems, quiet diesel engines, and noise-dampening technologies challenging acoustic detection​

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Quantum Sensing Integration: The Future ASW Paradigm

Multi-Sensor Fusion Architecture

India’s planned ASW enhancement integrates quantum magnetometers within a multi-sensor fusion framework:​

Layer 1 – Acoustic Sensors:

• Ship-mounted sonars, towed arrays, helicopter dipping sonars, sonobuoys from P-8I

Layer 2 – Quantum Magnetic Sensors:

• Aircraft/UAV-mounted quantum magnetometers scanning for magnetic anomalies at picotesla sensitivity​​

Layer 3 – Optical/Radar Sensors:

• Satellite imagery, EO/IR cameras, synthetic aperture radar detecting surface signatures (periscopes, snorkels)​

Layer 4 – Gravitational/Thermal Sensors:

• Quantum gravimeters detecting mass anomalies, thermal sensors identifying submarine wakes

AI-Driven Analytics:

• Machine learning algorithms processing vast sensor data, filtering false positives (geological features, shipwrecks), identifying genuine submarine threats in real-time​

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Global Quantum Race: Who’s Leading, Who’s Following

China’s Quantum Dominance Ambitions

Quantum Computing:

• Operates two of the world’s fastest quantum computers (Jiuzhang, Zuchongzhi)
• Heavy state investment—billions allocated annually to quantum R&D​

Quantum Radar:

• 2018 claims of quantum radar detecting stealth aircraft at long ranges (contested by experts)
• Ongoing research at universities and defense institutes​

Quantum Communications:

• Micius satellite (2016): World’s first quantum communication satellite demonstrating space-to-ground QKD
• Beijing-Shanghai quantum communication backbone: 2000+ km fiber-optic quantum network operational​

Quantum Sensing:

• April 2025: Chinese scientists tested drone-mounted quantum sensor (CPT atomic magnetometer) for submarine detection, overcoming low-latitude magnetic field blind spots in South China Sea​
• System uses 20-meter cable to reduce electromagnetic interference, integrates with fluxgate magnetometer and GPS for noise reduction​

United States’ Quantum Leadership

DARPA Programs:

• Quantum sensing for navigation, timing, radar applications
• Post-Quantum Cryptography standardization to counter quantum computing threats​

Quantum Radar Prototypes:

• Research into entangled-photon radar for stealth aircraft detection
• Naval applications for submarine and surface vessel tracking​

Quantum Computing:

• IBM, Google, Rigetti leading commercial quantum computing with 100+ qubit systems
• National Quantum Initiative Act (2018) allocating substantial federal funding​

Other Global Players

Russia: Quantum communications for military, quantum radar development

United Kingdom: National Quantum Technologies Programme investing £1 billion+

Japan & Australia: Quantum technology partnerships with US under AUKUS framework, quantum sensing R&D​

India’s Positioning

Strengths:

• Strong theoretical physics foundation: IITs, IISc producing world-class quantum research
• National Quantum Mission: ₹6,003.65 crore dedicated funding
• Startups ecosystem: QpiAI, BosonQ Psi, TCS Quantum Lab driving innovation​

Challenges:

• Commercial application lag: Gap between research and operational deployment
• Supply chain dependencies: Foreign hardware for quantum components
• Investment gap: China and US invest significantly more; India must accelerate funding​

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Beyond Submarines: Quantum’s Defense Arsenal

Quantum Communications: Unhackable Military Networks

June 2025 DRDO-IIT Delhi Breakthrough:

Scientists demonstrated quantum entanglement-based free-space secure communication over 1+ km—India’s first such achievement.​

Technical Achievement:

• Secure key rate: 240 bits per second
• Quantum Bit Error Rate (QBER): Less than 7% (well within secure thresholds)
• Method: Entanglement-assisted QKD via free-space optical link (no fiber cables required)​

Security Advantage:

Any eavesdropping attempt disturbs entangled photon states—instantly detectable. Even if hardware is compromised, entanglement ensures secure key distribution.​

Defense Applications:

• Battlefield communications: Secure command-control links immune to interception
• Satellite communications: Space-to-ground quantum links for strategic networks
• Submarine communications: Quantum-secured communication buoys​

Previous Milestones:

• 2022: India’s first intercity quantum link (Vindhyachal-Prayagraj) using commercial fiber
• 2023: QKD extended to 380 km over standard telecom fiber
• 2024: 100 km demonstration​

Quantum Radar: Stealth Detection

Entangled-photon radar theoretically detects stealth aircraft by exploiting quantum correlations resistant to electronic countermeasures. DRDO labs conducting theoretical research following global trends.​

Potential Applications:

• Stealth fighter detection (J-20, F-35)
• Cruise missile tracking
• Space debris monitoring​

Quantum Navigation: GPS-Denied Operations

Ultra-precise atomic clocks enable inertial navigation when GPS is jammed or unavailable.​

Military Applications:

• Submarine navigation: Independent of surface GPS signals
• Underground operations: Bunker assaults, tunnel warfare
• Spacecraft/missile guidance: Long-duration missions requiring time precision​

Quantum Computing: Breaking Codes, Securing Systems

Offensive Applications:

• Breaking adversary encryption: Quantum computers potentially breaking RSA, ECC encryption securing military communications
• Signals intelligence (SIGINT): Processing vast intercepted data in real-time​

Defensive Requirements:

• Post-Quantum Cryptography (PQC): Urgent deployment of quantum-resistant algorithms across military systems to prevent “harvest now, decrypt later” attacks​

Operational Applications:

• Logistics optimization: Quantum algorithms solving complex supply chain problems
• AI/ML acceleration: Quantum-enhanced machine learning for threat detection, battle management​

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Challenges and Vulnerabilities: The Honest Assessment

Technical Hurdles

Environmental Factors:

• Ocean variability: Depth, temperature, salinity affecting sensor performance
• Magnetic field variations: Earth’s natural magnetic fluctuations requiring sophisticated filtering algorithms
• Weather conditions: Turbulence, precipitation impacting aerial sensor platforms​

Sensor Limitations:

• Detection range: 100-200m depth constraint requires multiple aerial passes over suspected areas
• False positives: Distinguishing submarine signatures from geological features (iron ore deposits), shipwrecks, large marine life​
• Real-time processing: Vast data streams demand high-performance computing for timely threat identification​

Strategic Vulnerabilities

Quantum Threat to Current Encryption:

Quantum computers threaten current encryption standards (RSA-2048, ECC)—potentially decrypting classified military communications. The “harvest now, decrypt later” threat sees adversaries collecting encrypted data today to decrypt when quantum computers mature.​

Urgent Mitigation:

• Deploy Post-Quantum Cryptography (PQC) across all military systems
• Implement quantum-resistant algorithms (lattice-based, hash-based cryptography)
• Hybrid systems combining classical and quantum-resistant encryption during transition​

Adversary Countermeasures:

Degaussing: Submarines can reduce magnetic signatures through degaussing coils generating opposing magnetic fields​

Non-magnetic materials: Future submarines incorporating composite materials, titanium alloys reducing ferromagnetic content

Electronic countermeasures: Potential jamming of quantum sensor platforms (though quantum entanglement-based systems offer intrinsic security)​

Operational Integration Challenges

Technology Transition:

• Lab prototypes to field-deployable ruggedized systems—significant engineering challenge
• Environmental testing across diverse ocean conditions (Arctic to tropical)​

Personnel Training:

• Quantum technology operations requiring specialized skill sets
• Integration with existing ASW tactics, techniques, procedures (TTPs)​

C3I Architecture Integration:

• Quantum sensors feeding data into Command, Control, Communications, Intelligence (C3I) networks
• Interoperability with Navy, Air Force, Coast Guard systems​

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Way Forward: Strategic Recommendations for India

1. Accelerate Development Timeline

Action: Fast-track quantum sensing prototypes from lab to operational deployment

Measures:

• Increased R&D funding matching China’s investment levels
• Dedicated quantum sensor testbeds simulating maritime environments
• Parallel development of aircraft/UAV integration kits​

2. Build Comprehensive Quantum Ecosystem

Academia-Industry-Defense Partnerships:

• Expand DRDO-IIT collaborations beyond Delhi to IISc, IIT Bombay, IIT Madras
• Industry integration via Defence Innovation Organisation’s i-DEX initiative
• Startup incubation supporting quantum hardware/software companies​

Workforce Development:

• Quantum engineering programs in universities
• Scholarships for quantum physics, engineering students
• Lateral recruitment of quantum experts into DRDO​

Infrastructure:

• Quantum technology parks co-locating research, industry, testing facilities
• Fabrication facilities for quantum devices ensuring supply chain autonomy​

3. Operational Integration Strategy

Multi-Domain Sensor Fusion:

• Quantum + acoustic + optical + radar integrated ASW architecture
• AI/ML platforms automating threat detection, reducing operator workload​

Distributed Sensor Networks:

• Underwater sensor arrays with quantum magnetometers at strategic chokepoints
• Aerial surveillance grids: P-8I, MH-60R, UAVs with quantum sensors providing persistent coverage​

Quantum-Secure Communications:

• QKD networks linking sensors, command centers, fleet units
• Satellite-based quantum communication enabling secure long-range coordination​

4. Address Encryption Vulnerabilities

Urgent PQC Deployment:

• Immediate audit of military encryption systems identifying quantum-vulnerable protocols
• Procurement of quantum-resistant cryptography suites
• Phased migration timeline ensuring no security gaps​

Hybrid Encryption During Transition:

• Combine classical and quantum-resistant algorithms
• Quantum Key Distribution for highest-sensitivity communications​

5. Strategic Positioning

Indo-Pacific Quantum Leadership:

• Position India as quantum technology hub for friendly nations
• Capacity building for ASEAN, Gulf Cooperation Council partners
• Technology sharing within Quad framework (India-US-Japan-Australia)​

South-South Cooperation:

• Lead Global South nations in quantum capacity building
• Counter China’s quantum technology exports with Indian alternatives​

Supply Chain Resilience:

• Atmanirbhar Bharat in quantum domain—indigenize components from materials to systems
• Reduce dependence on foreign quantum hardware suppliers​

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Conclusion: The Quantum Imperative

DRDO Chief Dr. Samir V. Kamat’s revelation about quantum sensing for submarine detection at 100-200m depths marks more than a technological milestone—it signals India’s recognition that 21st-century defense demands quantum capabilities.​​

The strategic context is unambiguous: Chinese submarines prowl the Indian Ocean, Pakistan acquires eight advanced Hangor-class boats, and critical sea lanes carrying India’s energy lifeline face growing threats. Traditional acoustic ASW methods struggle against modern submarine stealth—quantum sensing offers a paradigm shift.​

But quantum’s defense applications transcend submarines. The Quantum Technology Research Centre inauguration, National Quantum Mission’s ₹6,003.65 crore investment, and DRDO-IIT Delhi’s quantum communication breakthrough demonstrate comprehensive quantum ecosystem development.​

Yet challenges persist. Technical hurdles—environmental factors, sensor limitations, real-time processing demands—require sustained R&D. Strategic vulnerabilities—quantum threats to current encryption, adversary countermeasures, supply chain dependencies—demand urgent mitigation.​

Quantum technology represents a critical frontier spanning security, science & technology, governance, international relations, and strategic studies. Questions will increasingly probe:

• Quantum technology’s defense applications and strategic implications
• India’s quantum ecosystem vis-à-vis China, US, and global competitors
• Maritime security challenges in Indo-Pacific and quantum ASW solutions
• Post-Quantum Cryptography and national security vulnerabilities
• Atmanirbhar Bharat in high-technology domains​

The global quantum race intensifies—China investing billions, US leading commercial applications, Europe coordinating national programs. India must accelerate or risk falling behind in a domain defining military superiority for decades.​

Indigenous development is non-negotiable. Quantum technologies represent dual-use capabilities applicable across defense, telecommunications, finance, healthcare, navigation. Foreign dependence creates strategic vulnerabilities—adversaries controlling quantum supply chains hold nations hostage.​

As emphasized during QTRC’s inauguration, India must urgently advance quantum technology for strategic and defense applications. Delay risks losing the competitive edge in a crucial military domain where quantum sensing, communications, computing, and radar determine who controls the seas, skies, and information domains.​

The ultimate vision: India as a quantum technology power securing maritime domains, deterring adversaries, and ensuring strategic autonomy in the Indo-Pacific and beyond. The question isn’t whether India can afford quantum investments—it’s whether India can afford not to invest when adversaries already are.​

Submarines may hide in ocean depths, but in the quantum era, even silence leaves signatures. And India is learning to read them.

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