DRDO partners with Zero mK India on 20 mK cryogenic dilution refrigerator

On September 24, 2026, the Defence Research and Development Organisation (DRDO) marked a major milestone in India’s deep-tech self-reliance drive by executing its first high-value agreement under the Technology Development Fund (TDF) scheme for the indigenous development of a 20 millikelvin (mK) dilution refrigerator. The agreement was formally signed in New Delhi between the Director of the TDF scheme and representatives of Zero mK India Private Limited, an emerging deep-tech startup based in Alwar, Rajasthan. This landmark deal represents the initial project sanctioned under a specialized 500 crore rupee corpus approved by Union Defence Minister Rajnath Singh to support high-risk, cutting-edge technology development across domestic industry. Under the terms of the project, DRDO’s Solid State Physics Laboratory (SSPL) will act as the nodal technical institution, providing direct mentoring, research guidance, and system evaluation to support the startup from design through prototype validation.

The signing underscores a deliberate pivot by India's defence establishment to address critical technological chokepoints in frontier science and strategic hardware. While conventional defence indigenization programs have historically focused on airframes, armored vehicles, and missile assemblies, modern electronic warfare, secure communications, and quantum computing rely heavily on specialized laboratory infrastructure that has traditionally been imported. Dilution refrigerators capable of reaching millikelvin temperatures—temperatures hovering just fractions of a degree above absolute zero—represent one of the most tightly restricted dual-use technologies on the global market. By backing a domestic enterprise to build this complex cryogenic apparatus, DRDO aims to eliminate external dependencies and foster a resilient ecosystem capable of supporting national quantum initiatives and advanced defence R&D.

Technical mechanics and thermal engineering of dilution refrigeration

To understand the engineering complexity of a 20 mK dilution refrigerator, one must look at the extreme thermodynamic principles governing ultra-low temperature physics. Standard mechanical refrigeration and liquid nitrogen or liquid helium cooling loops reach baseline limits of roughly 77 Kelvin and 4.2 Kelvin, respectively. Pumping on liquid helium-4 can lower temperatures to approximately 1 Kelvin, but reaching sub-Kelvin regimes in the millikelvin range requires exploiting the quantum mechanical properties of helium isotopes. A dilution refrigerator operates using a closed mixture of two stable isotopes: helium-3 and helium-4. When this isotopic mixture is pre-cooled below approximately 0.8 Kelvin, it spontaneously undergoes phase separation into two distinct liquid layers. The upper layer consists of nearly pure helium-3, known as the concentrated phase, while the lower layer consists of helium-3 dissolved in superfluid helium-4, known as the dilute phase.

The core thermodynamic work occurs inside the mixing chamber of the refrigerator. Because helium-3 atoms possess a non-zero finite solubility in superfluid helium-4 even as temperatures approach absolute zero, helium-3 can be continuously drawn across the phase boundary from the concentrated phase into the dilute phase. This phase transition behaves analogously to the evaporation of a liquid into a gas, absorbing latent heat from the surrounding metal body of the mixing chamber. By continuously pumping helium-3 gas out of the dilute phase in a lower-temperature still chamber, re-condensing it through a series of multi-stage heat exchangers, and returning it to the concentrated phase, the system maintains continuous cooling. Achieving a stable 20 millikelvin temperature—roughly 135 times colder than the deep vacuum of interstellar space—demands extraordinary engineering precision across every subsystem.

Building such a system requires integrating high-vacuum isolation chambers operating at pressures below 10^-6 mbar, ultra-pure gas handling manifolds, hermetically sealed oil-free pumps, and custom counter-flow heat exchangers with ultra-high thermal contact surface areas. Furthermore, mechanical vibrations generated by turbomolecular and backing pumps must be meticulously dampened through multi-tier isolation stages to prevent micro-seismic vibrations from transferring thermal energy into the ultra-cold sample stage. Thermal anchoring of electrical wiring and coaxial signal lines entering the cold zone is another major hurdle; every wire passing from room temperature to 20 mK must be thermally intercepted at intermediate temperature stages using attenuation blocks and high-purity copper or superconducting leads to minimize thermal conductive load while preserving signal integrity for sensitive microwave pulses.

Strategic alignment with the National Quantum Mission

The development of domestic 20 mK dilution refrigeration infrastructure directly aligns with the objectives of India’s National Quantum Mission (NQM). Superconducting quantum computing architectures—which use Josephson junctions to create artificial two-level atom systems or qubits—require operating environments in the 10 to 20 mK range. At ambient room temperatures, thermal energy vastly exceeds the minute energy level splitting of superconducting qubits, causing immediate thermal excitation and rapid destruction of quantum coherence. Cooling the processor down to 20 mK suppresses thermal phonons and thermal noise to negligible levels, allowing qubits to remain in fragile superposition and entangled states long enough to execute quantum logic gates and complex algorithms.

Until now, Indian quantum researchers and defence laboratories have relied almost exclusively on dilution refrigerators sourced from a handful of foreign manufacturers in Europe and North America. Procurement of these systems involves substantial capital expenditure, extended delivery lead times, and complex international export licensing under multilateral control regimes. Furthermore, global supply chains for critical cryogenic components and specialized gases like helium-3 remain highly vulnerable to geopolitical disruptions. Establishing a domestic manufacturing capability for 20 mK refrigerators ensures data sovereignty, unrestricted research continuity, and complete autonomy over sensitive defence testing. It provides Indian scientists and military engineers with ready access to the environmental test beds needed to evaluate indigenous quantum processors, ultra-sensitive quantum magnetometers, low-noise amplifiers, and cryogenic field-effect transistors.

The role of TDF and institutional mentorship in deep-tech scaling

The selection of Zero mK India Private Limited highlights the evolving role of the Technology Development Fund as a catalyst for deep-tech innovation within the Indian defence sector. Executed by DRDO under the Ministry of Defence, the TDF scheme provides grant-in-aid funding up to 50 crore rupees per project, covering up to 90 percent of total development costs for MSMEs, startups, and industrial partners. By absorbing the high financial risk inherent in frontier technology development, the scheme enables small, specialized engineering firms to undertake projects that would otherwise be commercially unviable for private capital. The dedicated 500 crore rupee deep-tech corpus specifically targets disruptive, long-gestation technologies that underpin future warfare capabilities.

Crucial to the success of this model is the technical mentorship provided by established DRDO laboratories. For the 20 mK dilution refrigerator project, the Solid State Physics Laboratory (SSPL) in Delhi brings decades of expertise in solid-state physics, material characterization, and low-temperature instrumentation. SSPL researchers will collaborate closely with Zero mK India's engineering team to oversee design reviews, component benchmarking, and performance validation. Early technical roadmaps target the delivery of an operational functional prototype by late 2027, with subsequent efforts focused on scaling cooling power, optimizing continuous run times, and simplifying automated control systems for wider deployment across academic, industrial, and defence research centers.

Commercial spillovers and expanding the industrial cryogenic base

Beyond quantum computing, the technology stack built around 20 mK dilution refrigerators generates substantial engineering spillovers across broader industrial and defence domains. The development of ultra-reliable, leak-tight gas handling systems, high-vacuum chambers, and cryogenic fluid management hardware directly benefits next-generation aerospace testing, space simulation chambers, and high-energy physics research. Techniques perfected in precision thermal management, automated gas purification, and non-destructive testing at millikelvin scales can be adapted to enhance high-pressure gas distribution, cryogenic propellant handling, and specialized environmental test benches.

As India accelerates its drive toward self-reliance across strategic sectors, building domestic capability in frontier cryogenics and high-precision testing infrastructure is no longer optional. Translating complex thermodynamic designs from laboratory models into rugged, field-deployable platforms requires uncompromising rigor in fluid control, structural isolation, and automated validation. Indigenous test benches, custom high-pressure gas handling systems, and advanced cryogenic test rigs play a pivotal role in this ecosystem—enabling defence labs, aerospace manufacturers, and industrial pioneers to rigorously qualify cutting-edge hardware under the most demanding environmental conditions.