Amid the growing threat of powerful computing systems that can break conventional encryption, the quantum key distribution (QKD) technology to secure information transmission offers a future-proof solution.
QKD manages the upward and downward flow of encrypted information to the satellite from the ground and vice-versa. India’s diverse atmosphere adds both complexity and opportunity to this process.
In an exclusive interview with AIM, Urbasi Sinha, professor at the Raman Research Institute (RRI), explained her recent research on estimating the signal strength, atmospheric losses, and alignment for secure satellite-to-ground quantum communication.
The study takes into account three locations to identify ideal sites for ground stations for quantum communication. The scientists studied Mount Abu, Nainital, and Hanle (Ladakh) to assess atmospheric properties such as static (dust, gas, vapour) and dynamic (wind, turbulence) particles.
This research, conducted with Satya Ranjan Behera, a PhD holder in astrophysics and scientist at RRI, for the ISRO-QKD project, marks a critical step toward satellite-based quantum communication, where maintaining signal integrity over vast distances is key.
Quantum Communication Will Not Replace 5G
Here, the first question that arises is whether this tech will replace our existing modes of communication, like 5G or even future technologies like 6G. Short answer: No.
While groundbreaking, quantum communication is unlikely to replace classical communication systems. It’s valuable in more strategic security-driven sectors like defence, banking, and healthcare, serving as an additional security layer in fields where data protection is critical.
“We’re not talking about the eradication of something and replacement altogether. What we’re doing is adding a different layer for the key distribution part,” Sinha explained. This means sectors such as government communications may as well adopt quantum solutions to safeguard against algorithmic attacks.
Essentially, classical systems will remain dominant in everyday consumer and corporate communication, while Quantum communication will focus on enhancing secure key distribution, not on overhauling existing infrastructure.
Quantum Leaves a Footprint
For quantum communication, it is essential to ensure that encrypted information in transmission remains virtually impossible to intercept or decode. While it’s often described as unbreakable, American mathematician Claude Shannon called it “information-theoretically secure” in 1949.
Most importantly, Sinha said that when someone attempts to intercept a key in quantum, any interference introduces detectable changes, and the eavesdropper inevitably ends up leaving a trace. If errors exceed a defined threshold, the system discards the compromised key, ensuring the communication remains secure.
As quantum communication evolves, ethical considerations gain importance. Sinha also stressed the need for advancements in ethical hacking to address vulnerabilities and develop robust defences.
AI to Enhance the Optics
To address the challenges posed by atmospheric conditions, these Indian researchers are now turning to AI and ML tools.
“We are investigating adaptive AI optic solutions, which would have a self-correction mechanism,” Sinha said.
These technologies aim to mitigate signal disruptions caused by atmospheric variability, ensuring secure and reliable communication. AI-driven strategies, coupled with adaptive optics, enable real-time adjustments, compensating for distortions caused by dynamic atmospheric properties like turbulence and dust.
This innovative use of AI ensures that quantum communication systems can maintain accuracy and efficiency, even in challenging environments.
The ISRO Partnership Continues
While sites like Ladakh’s Hanle Observatory show great potential due to existing scientific infrastructure, it is also geopolitically sensitive, given its proximity to China. “We’ve analysed publicly available data and identified favourable locations, but where implementation occurs isn’t in our jurisdiction,” clarified Sinha.
While the region’s strategic importance raises concerns about national security and government approvals, the research remains R&D-focused. Findings provide a template for broader applications, setting the stage for quantum communication to advance despite geopolitical complexities and logistical hurdles.
India’s advancements in quantum communication are set to progress, and potential future collaborations are in the works. The QUEST project, funded by ISRO, achieved critical ground-based milestones, including India’s first successful free-space QKD experiment and demonstrations of quantum communication between buildings.
As the QUEST project concludes, ISRO plans to transition toward engineering-focused development for satellite deployment. Having developed the necessary groundwork, the team anticipates continuing their involvement.
“It would be a shame not to contribute further after achieving such significant progress,” Sinha expressed. These collaborations signal India’s growing commitment to advancing quantum technology on a global stage.
Uplink vs Downlink Signaling
While quantum technology has immense potential, its journey toward mainstream adoption is hindered by costs, complexity, and awareness. Though not necessarily a cheap solution, it’s a good one. The science and technology ministry has also acknowledged the need for time and innovation to bridge these gaps with India’s National Quantum Mission.
However, a key challenge lies in quantum communication’s uplink and downlink processes. Downlink, already demonstrated by a few countries, allows photons to travel through ideal conditions before hitting Earth’s atmosphere.
Conversely, uplink photons immediately face atmospheric interference, causing instant vulnerabilities. However, uplink holds unique advantages: the photon source remains on Earth, enabling upgrades over time, unlike satellites, where alterations post-launch are quite difficult and cost-efficient.
Uplink provides scientists with the thrill of tackling harder problems. Moreover, uplink’s technological demands could spur innovations, such as advanced atmospheric mitigation tools and space-compatible detectors.
Why is Quantum Communication Difficult?
Conducting research across diverse sites often poses unique problems for the researchers, particularly in data acquisition and multidisciplinary analysis.
“One of the basic challenges we faced was actually getting good data for various sites,” Sinha explained. The team had to rely on publicly available atmospheric data, which influenced their choice of locations since that data was already available to ISRO.
The project also required tools and expertise beyond traditional quantum research. For instance, ‘link budget analysis’, commonly used in astrophysics to optimise observational setups, became essential. Collaboration with Behera, who has a PhD in the field, proved invaluable.
Additionally, the research demanded specialised tools for static atmospheric analysis, which were expensive and required procurement, as well as custom-built tools for dynamic analysis.
As for the most important tool, the telescope, its design further required advanced optical simulation tools. This interdisciplinary approach, integrating atmospheric studies, optics, and quantum science, marked a unique and complex challenge for the team.
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