Breakthrough in Nanoscale Light Control: IISc Researchers Advance Quantum Communication and Photonic Devices

The findings, published in Advanced Optical Materials, represent a major step forward in the development of on-chip photonic quantum information systems.

Researchers at the Indian Institute of Science (IISc), Bangalore, have unveiled a groundbreaking platform for controlling light at the nanoscale, paving the way for advancements in quantum communication, data encryption, and next-generation photonic devices.

The research team, led by Prof. Jaydeep K. Basu from IISc’s Department of Physics, in collaboration with Prof. Shankar Kumar Selvaraja from the Centre for Nano Science and Engineering (CeNSE) and theoretical insights from Prof. Girish S. Agarwal of Texas A&M University, achieved a significant breakthrough by integrating two-dimensional (2D) semiconductor colloidal quantum wells (CQWs) with dielectric metasurface resonators (MSRs).

This integration resulted in unprecedented emission line narrowing, a 12-fold increase in brightness, and long-range photon transport at room temperature. The findings, published in Advanced Optical Materials, represent a major step forward in the development of on-chip photonic quantum information systems.

Key Advances and Potential Applications

The researchers used Cadmium Selenide (CdSe)-based CQWs combined with a guided mode MSR fabricated on a silicon nitride (SiN) slab-waveguide platform. The MSR design features a precise square-lattice arrangement of holes, enabling narrow resonances in both in-plane and out-of-plane directions.

The resulting spectral overlap between the MSR’s narrow-band response and the CQWs’ broader emission achieved a remarkable 97% reduction in spectral line width, ensuring high spectral purity. Additionally, the platform demonstrated photon transport across the chip over distances of up to 1 mm, highlighting its potential for compact, efficient quantum devices.

“This innovation allows exceptional control over light emission and transport, which is critical for the next generation of quantum technologies,” said Prof. Basu.

Enabling Quantum Technology: From Cryptography to Sensing

The cutting-edge platform offers transformative potential in several fields:

• Quantum Cryptography: High-efficiency single-photon sources could secure encrypted communications against hacking.
• Quantum Information Processing: On-chip photon transport enables scalable quantum computing solutions.
• Advanced Sensing: Spectrally pure light sources enhance the accuracy of quantum metrology and sensing technologies.

To measure these enhanced light properties, the team utilized a state-of-the-art confocal photoluminescence (PL) setup funded by the DST-FIST program, ensuring precision in their results.

Future Directions

Building on this success, the researchers plan to integrate single quantum emitters (SPEs) with metasurface resonators. This development would create highly efficient single-photon sources, essential for quantum cryptography and advanced quantum information processing systems.

By combining the spectral filtering capabilities of MSRs with the precise emission of SPEs, the IISc team aims to unlock new possibilities in secure communication, quantum sensing, and photonic device miniaturization.

A Milestone in Photonic Innovation

This breakthrough reinforces the role of nanoscale materials in transforming quantum photonics. The ability to seamlessly control and manipulate light emission at the nanoscale opens the door to a future of secure, efficient, and compact quantum technologies.

As these findings gain recognition globally, the IISc researchers’ contributions promise to reshape the landscape of quantum communication and photonic device innovation.