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Using existing telecom fibers: IUCAA lab develops critical technology for quantum networks

Prof Subhadeep De, Principal Investigator of the Precision and Quantum Measurement Laboratory (PQM-lab) at IUCAA and his team are redefining how light can be used to connect distant places with unprecedented precision.

3 min readUpdated: Jan 12, 2026 10:20 PM IST

Prof Subhadeep De, (Right) with Dr Stanley Johnson (left) at IUCAA's Precision and Quantum Measurement Laboratory (PQM-lab). (Express Photo)

The Precision and Quantum Measurement Laboratory (PQM-lab) at the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune has developed a critical technology, PhotonSync, that uses normal telecom optical fibers and uplift our capability to build a quantum network among sensors, computers, and communication.

Prof Subhadeep De, Principal Investigator of the Precision and Quantum Measurement Laboratory (PQM-lab) at IUCAA and his team are redefining how light can be used to connect distant places with unprecedented precision. Together with his postdoctoral fellow, Dr. Stanley Johnson, Prof. De has designed, developed, and experimentally demonstrated an ultra-stable Phase-Coherent Fiber (PCF) link using entirely indigenously developed hardware.

“This breakthrough system has been named PhotonSync—a technology that uses photons themselves to synchronize geographically separated locations with extraordinary stability. PhotonSync transforms an ordinary telecom optical fiber into a highly specialized, ultra-stable link, capable of transferring information encoded in photons while preserving their precisely defined quantum characteristics over long distances,” Prof De told The Indian Express.

The scientific foundations and experimental validation of PhotonSync have been published in a reputed international journal Communications Physics and the innovation has been further strengthened by securing a trademark for the name PhotonSync and patenting of the underlying intellectual property. The IUCAA team has already demonstrated stable performance over fiber lengths of up to 80 km, with ambitious plans to scale the system to 1000 km.

In collaboration with Prof. Anirban Pathak and Dr. Sandeep Mishra from the Jaypee Institute of Information Technology (JIIT), Noida the team has established the relevance of the PCF link for twin-field quantum key distribution (TFQKD), a leading protocol for long-distance quantum-secure communication. Together, these advances position PhotonSync and the PCF technology as key enablers of future quantum communication infrastructure, bringing the vision of large-scale, secure quantum networks closer to reality.

Photons—the tiny quanta of light—are remarkable messengers, Prof De said. “Photons are usually encoded in their phase, polarization, electro-magnetic modes for carrying the desired data. In quantum communication, these photons act as qubits, faithfully transporting delicate quantum states from one end of a fiber to the other, where they are finally decoded using quantum measurement techniques,” he added.

For the first time in India, IUCAA has developed the critical technology, Prof De said adding that they named the core technologyas PhotonSync that uses normal telecom optical fibers and stabilize and making it suitable for variety of sophisticated applications.

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Among the applications include enhancing capability of the optical fiber-based quantum communication, long distance entanglement, eventually leading to quantum internet, intercomparing atomic clocks with unprecedented accuracy those are situated distant apart and the ultrastable channel to build a quantum network among sensors, computers, and communication. “Indigenization of this technology is dedicated to the national effort towards Viksit Bharat,” he added

Anuradha Mascarenhas

Anuradha Mascarenhas is a Senior Editor at The Indian Express, based in Pune. With a career spanning three decades, she is one of the most respected voices in Indian journalism regarding healthcare, science and environment and research developments. She also takes a keen interest in covering women's issues . Professional Background Education: A gold medalist in Communication and Journalism from Savitribai Phule Pune University and a Master’s degree in Literature. Author: She authored the biography At The Wheel Of Research, which chronicles the life and work of Dr. Soumya Swaminathan, the former Chief Scientist at the WHO. Key Focus: She combines scientific accuracy with storytelling, translating complex medical research into compelling public and human-interest narratives. Awards and Recognition Anuradha has won several awards including the Press Council of India's national award for excellence in journalism under the gender based reporting category in 2019 and the Laadli Media award (gender sensitivity -2024). A recipient of the Lokmat journalism award (gender category-2022), she was also shortlisted for the RedInk awards for excellence in journalism-2021. Her debut book At The Wheel Of Research, an exclusive biography of Dr Soumya Swaminathan the inaugural chief scientist of World Health Organisation was also nominated in the Popular Choice Category of JK Paper AUTHER awards. She has also secured competitive fellowships including the Laadli Media Fellowship (2022), the Survivors Against TB – New Research in TB Media Fellowship (2023) and is part of the prestigious 2025 India Cohort of the WomenLift Health Leadership Journey.” Recent Notable Articles (Late 2025) 1. Cancer & Specialized Medical Care "Tata Memorial finds way to kill drug-resistant cancer cells" (Nov 26, 2025): Reporting on a breakthrough for triple-negative breast cancer, one of the most aggressive forms of the disease. Discipline, diet and purpose; How a 97-year-old professor defies ageing'' (Nov 15, 2025) Report about Prof Gururaj Mutalik, the first Head of Department at Pune's B J Government Medical College who at 97 credits his longevity to healthy habits and a strong sense of purpose. 2. Environmental Health (The "Breathless Pune" Series) Long-term exposure even to 'moderate' air leads to chronic heart, lung, kidney issues" (Nov 26, 2025): Part of an investigative series highlighting that even "safe" pollution levels are damaging to vital organs. "For every 10 µg/m3 increase in PM2.5 level, there was 6-8% jump in medicine sales" (Nov 23, 2025): Using commercial data to prove the direct link between air quality and respiratory illnesses in Pune. 3. Lifestyle & Wellness News "They didn't let cancer, diabetes and heart disease stop them from travelling" (Dec 22, 2025): A collaborative piece featuring survivors who share practical tips for traveling with chronic conditions. At 17, his BP shot up to 200/120 mmHG; Lancet study flags why child and teen hypertension doubled between 2000 and 2020'' (Nov 12,2025)--A report that focusses on 17-year-old-boy's hypertensive crisis and reflects the rising global trend of high blood pressure among children and adolescents. 4. Scientific Recognition & Infrastructure For promoting sci-comm, gender diversity: IUCAA woman prof highlighted in Nature" (Nov 25, 2025): Covering the global recognition of Indian women scientists in gender studies and physics. Pune researchers find a spiral galaxy like the Milky Way from early universe'' (December 3, 2025)- A report on how Indian researchers discovered a massive galaxy that existed when the universe was just 1.5 billion years old , one of the earliest to have been observed so far. Signature Beat: Health, Science & Women in Leadership Anuradha is known for her COVID-19 reportage, where she was one of the first journalists to provide detailed insights into the Covishield and Covaxin trials. She has a dedicated interest in gender diversity in health and science, often profiling women researchers who are breaking the "leaky pipeline" in STEM fields. Her writing style is scrupulous, often featuring interviews with top-tier scientists and health experts from various institutions. ... Read More

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