About the Group
The Quantum Optics and Quantum Information Processing (QOQI) Group at the Indian Institute of Science conducts theoretical and experimental research in quantum information science, quantum optics, and quantum technologies. The group investigates fundamental aspects of quantum mechanics and quantum information, while developing photonic approaches to quantum computing, communication, and sensing. These efforts extend from fundamental studies, laboratory demonstrations and translating them to photonic quantum devices and systems for practical use.
Research philosophy
As we work on our research topics, we often find the need to extend the theoretical structures of quantum information to answer deeper underlying questions. These include: how can quantum walks be used to model and simulate the dynamics of physical, chemical, and biological systems? How can a single photon and multi-photon in combination of different degrees of freedom to engineer and control multi-qubit gate operation and scale it to larger number ?. Experimental ways to probe foundation aspects of quantum correlations and nonlocal behaviour ?, How can quantum protocols demonstrated in laboratory be turned into working devices like robust and compact computing, communication and sensing system beyond the laboratory bench?
When approaching a research question, our approach is to concentrate on understanding the principles, developing tools and platforms that not only answer the question at hand, but generalise to a broader class of problems, transiting between theoretical modelling and experimental realisation, rather than one-off demonstrations that solve only the problem immediately in front of us.
The lab's strength lies in its unique dual approach: developing theoretical quantum algorithms while simultaneously building experimental setups using single and entangled photons to realize these protocols in practice — turning conceptual advances into working quantum devices.
The Group operates within the Department of Electronic Systems Engineering (ESE) at IISc and is a key contributor to India's National Quantum Mission (NQM), serving as one of the Technology Group for photonic quantum computing research under the Quantum Computing Hub.
Research Focus Areas
- Quantum walk as algorithms to simualte and model relativistic quantum mechanical effects, system driven by Dirac equations, and neutrino oscillations within an open quantum system framework
- Algorithmic framework for energy transfer and active reaction center in biological and chemical complexes via quantum coherence
- Quantum walks for modeling nodes ranking in graphs and quantum quantum networks.
The QOQI group is developing light-based quantum computers which are naturally resilient to environmental noise making them an attractive route to practical, scalable quantum hardware. The group has developed quantum-walk based scheme for quantum computation and is further advancing a photonic quantum-walk architecture that uses the polarization and path degrees of freedom of photons to encode qubits and implement quantum gate operations and scale to larger number of qubits.
Reference results: The lab has developed India's first six-qubit photonic quantum system — a world-first demonstration of deterministic two- and three-qubit quantum gate operations using photonic qubits in conbination of different degrees of frredom of photons. The team encodes three qubits within a single photon (one via its polarization state, two via spatial path encoding) and entangles two such photons to create a six-qubit GHZ (Greenberger–Horne–Zeilinger) entangled state.
Building on this platform, the group has also designed vairous quantum circuits and demonstrated deterministic quantum teleportation of a path-encoded qubit using entangled photons in three-qubit setting, public and private key generation and quantum phase estimation in four-qubit setting
The group develops protocols for secure communication and long-range signal detection, including:
- Quantum Key Distribution (QKD) using single- and entanged photon sources in multi-qubit configuration
- Secured quantum keys using correlated quantum randomness combination from multi-qubit photonic systems
- Entanglement-certifed quantum rnadom number generator (QRNG)
Reference results: True random numbers are essential for secure cryptography. The lab has developed a fully functional quantum random number generator that operates at a high bit rate of 70–80 Mbps using path-entangled single photons. The device has passed the full suite of National Institute of Standards and Technology (NIST) randomness tests, and its quantumness has been self-certified through violation of the CHSH (Clauser–Horne–Shimony–Holt) inequality.
- Quantum magnetometry using discrete-time quantum walks
- Quantum illumination using polarization-path entangled photon pairs and hyper-entangled states