Rajesh Kumar Krishnan is a PhD candidate in the Electro-Optical Communications (ECO) group of the Department of Electrical Engineering at Eindhoven University of Technology (TU/e), working under the supervision of dr.ir. S. Rommel and prof.dr.ir. I. Tafur Monroy. His research focuses on the advanced physical-layer optimization of Quantum Key Distribution (QKD) systems, pushing secure quantum communication from theoretical protocols toward robust, deployable links. From characterizing noise budgets and secret-key-rate limits to designing adaptive control schemes that keep quantum channels stable under real-world conditions, his work bridges the gap between quantum optics and practical optical networking.

Rajesh brings a proven track record of translating quantum security from the lab into the field. Under his engineering leadership, QNu Labs has consistently turned complex quantum lab work into deployable, commercial-grade realities, directly contributing to the nation's milestone achievements under the National Quantum Mission (NQM), including the development of one of India's first commercial quantum random number generators (QRNG). His QKD work spans an unusually broad operating envelope, from single-node links at the 200 km scale through to long-haul deployments approaching 1000 km, and across both fiber-based and free-space channels, giving his research a rare end-to-end perspective that connects device-level entropy sources to network-scale quantum key distribution.

At TU/e, his work cuts across the full landscape of QKD protocols, including differential-phase-shift (DPS) and decoy-state QKD, entanglement-based QKD, continuous-variable QKD (CV-QKD), measurement-device-independent QKD (MDI-QKD), and Twin-Field QKD. He combines theoretical modeling and rigorous security analysis with a hard practical question: not just whether each protocol can generate provably secure keys, but where, how far, and at what rate they hold up over real deployed fiber. Working from first principles, he derives secret-key-rate bounds and security proofs within the decoy-state formalism and translates them into link-planning and noise-budgeting frameworks that yield concrete feasibility and key-rate predictions across multi-node, multi-link network topologies. At the heart of this is a harder problem than point-to-point security: making quantum channels live inside the classical network. Rajesh tackles the coexistence of quantum and conventional traffic on shared infrastructure, wavelength assignment in hybrid quantum-classical networks, and the orchestration and control schemes that allow the two to be provisioned, monitored, and managed as one system.

Rajesh is further interested in photonic integration as a route to compact, scalable QKD hardware, and in the physical-layer engineering, from advanced optical fibers to adaptive signal processing, that underpins reliable long-distance quantum links. His broader goal is to make QKD a practical building block of secure communication networks rather than a laboratory curiosity.

The hardest links to secure are the ones we assume are already safe

Rajesh K. Krishnan holds a Bachelor's degree in Electronics and Communications Engineering from Anna University (India) and a Master's degree in Very Large Scale Integration (VLSI) from Karunya Institute of Technology and Sciences (India). He further obtained a Master's degree in Artificial Intelligence for Computer Vision and Control from the Illinois Institute of Technology (Chicago, USA).

Rajesh brings over fifteen years of industry experience spanning hardware design, FPGA architecture, and quantum-safe cryptography. He began his career as a Hardware Design Engineer at Mistral Solutions and later served as Senior Hardware Design Engineer, before founding and leading Aabelon Embedded Technologies as Chief Executive Officer. In 2017 he joined QNu Labs, where he progressed from Project Lead through Product Manager and Vice President of Engineering to his current role as Senior Vice President of Innovation. Over nine years at QNu Labs, he led the realization of theoretical quantum concepts into scalable hardware and FPGA platforms, and built India's first Quantum Key Distribution system based on the Differential Phase Reference protocol.

He is currently pursuing his PhD in the Electro-Optical Communications (ECO) group of the Department of Electrical Engineering at Eindhoven University of Technology (TU/e), where his research focuses on the advanced physical-layer optimization of Quantum Key Distribution systems.