In past two decades or so, the technology related to photonics have seen tremendous growth in terms of miniaturization which is comparable to transformation happened with the electronic systems: Reducing it from bulky devices to atomic scale transistors on a single chip. The current technology is in a position to integrate optical circuits/components on a microchip. In fact, a small survey can easily reveal that the well-known Moore’s law can readily be applicable in photonic integrated circuits (PICs). Driven by the advancement in microfabrication, the commercialization of this architecture is now a reality and some of the world’s leading companies are into it. However, the main challenge with the classical PICs is scaling up on integrated platform and engaging laboratory-based innovations to real-life problems.

An emerging subset of integrated photonics circuits since 2008 is integrated quantum photonics which employs same classical PICs for quantum applications. At present different approaches have been adopted to make the quantum circuits on monolithic or hybrid platforms. Photonic Integrated Circuit Group at CQuERE deals with the applied aspects of photonics on an integrated platform. Our group is involved in studying novel properties of light on a chip-scale to develop technology for translational research. We seek to encompass both technological domains viz., classical and quantum. In context to quantum research, PICs has potential applications in quantum sensing, quantum communication, quantum information research, and quantum metrology. The research on integrated circuits for quantum photonics can be categorized into three main areas viz. quantum light sources, photonic integrated circuit platform, and single photon detectors. Currently, some of the research that we plan to pursue are: (i) Chem/bio sensing using PICs, (ii) single photon emitters in telecommunication wavelengths, and (iii) quantum (/classical) computing. Eventually we intend to extend our research on quantum networks as well.

Chem/bio sensing:

The area of bio-sensing is developing fast and has a lot of scopes to do new things. The truly interdisciplinary nature fits well into TCG CREST’s research motto and can be directly applied to human life. The idea is to develop is chip-based interferometric measurement platform that can work as a sensor for biological proteins, or a trace element present in the water solution. This approach can be fast with high degree of accuracy. The whole sensing scheme can be improved by using non-classical states of light. We are also exploring the possibility of using non-Hermitian systems for quantum enhanced sensing applications.

Single photon emitters:

Recently, single-photon emitters (SPE) have become prime candidate for research in integrated quantum optics and implementation of quantum technologies. Different materials are currently being investigated viz. epitaxial quantum dots, Colloidal quantum dots (CQDs), point defects in various semiconductors like diamond, silicon carbide, hexagonal boron nitride. Although epitaxial QDs suffers from integration-related problem with other quantum technology platforms, CQDs shows great potential due to its tunability over emission wavelength including telecom range by varying the sizes and composition. In addition, CQDs offer great flexibility to be integrated with existing quantum technology platforms for its solution-based synthesis processing routes. At present, our group is actively working on CQDs and point defect based SPEs.

Quantum computing:

One of the ways to establish quantum supremacy is to perform a task on quantum hardware that out-performs a classical machine in terms of time it takes to solve it. Although some of these problems don’t have direct use, it might reinforce the overall quantum hardware and software platform. In future, we intend to study multiphoton quantum dynamics in photonic waveguide lattices (networks). These network structures are driven by quantum interference and can be used for studying quantum walks and boson sampling.

We are now building the PICs research facilities from scratch, supported by highly trained researchers. The whole project involves various lasers and characterization tools. We are focusing on forming a team with diverse manpower (with thorough skill set) having close collaboration, both within and outside. The future achievements of photonic circuits will be governed by materials innovation, advanced integration, and packaging and we intend to contribute to this.

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