Abstract: Quantum technologies promise to revolutionize computing, sensing, and communication in ways we are only beginning to imagine. Many quantum materials and devices operate at low temperatures . Defects in solid-state materials can be particularly useful for quantum platforms as they can act as artificial atoms with discrete energy levels. As part of my PhD work, I have developed a confocal microscopy system integrated with a cryogenic setup, with capabilities for time-resolved photoluminescence (PL) and pulsed magnetic resonance measurement. I have used this system to study defects in diamond and WSe₂.

I will present experimental results on magneto-optically active qubits in nitrogen-vacancy (NV) centers in diamond. I will demonstrate pulsed protocols for coherent control of the NV spin and discuss their behavior when the NV center is coupled to nearby spin impurities in the diamond lattice. These effects are investigated in both ensemble NV systems and single NV centers, at both room temperature and low temperature.

Transition Metal Dichalcogenides (TMDs) has shown huge promise as quantum material platforms due to their ease in device integration and scalability. Recent reports have identified single-photon emission at low temperature from localized excitons associated with defect-related levels in TMDs [1]. In the second part of the talk, I will present my observation of long-lived excitonic emission from defect-related states in WSe₂ at 4 K. I will discuss their potential for future quantum technologies.

References

[1] . Dastidar, M. G., Thekkooden, I., Nayak, P. K., & Bhallamudi, V. P. (2022). Quantum emitters and detectors based on 2D van der Waals materials. Nanoscale, 14(14), 5289-5313

Event Details
Title: Investigations of solid-state defects at cryogenic temperature for applications in spin and photon-based quantum applications
Date: April 21, 2026 at 03:00 PM
Venue: HSB 210
Speaker: Mr. Immanuel Thekkooden (EE20D035)
Guide: Dr. Bhallamudi Vidya Praveen
Type: PHD seminar

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