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Vanadium color centers in silicon carbide for quantum-telecommunication in the O-Band

PhD ceremony:Mr J. (Joop) Hendriks
When:May 31, 2024
Supervisor:prof. dr. ir. C.H. (Caspar) van der Wal
Co-supervisor:dr. R.W.A. (Remco) Havenith
Where:Academy building RUG
Faculty:Science and Engineering
Vanadium color centers in silicon carbide for
quantum-telecommunication in the O-Band

In his PhD research, Joop Hendriks studied vanadium impurities in silicon carbide, and in particular properties that are important for application as a qubit in quantum computing. Contrary to many other material systems, these impurities emit light in the near infrared coinciding with the telecom O-band, such that losses of such photons in optical fibers are relatively small. 

By using two-laser spectroscopy, Hendriks studied the spin-relaxation dynamics in the ground state. By comparing the experimental results to a model, he derived that the decay of the nuclear spin is the slowest process. Next, Hendriks studied how the population difference between two states scan be increased. Depending on the temperature and the properties of the used laser light, the population difference can be significantly improved. 

Another important property is the coherence time, as it forms the upper limit of the useful lifetime of a qubit. By using a combination of optical and microwave pulses, Hendriks determined a lower limit for the coherence time of V defects. Furthermore, he observed that the V spin couples strongly to the nuclear spin of nearby isotopes. Finally, Hendriks fabricated SiC waveguides and demonstrated that light can be efficiently coupled in and stays confined to a small volume. This shows that these structures can be useful to enhance optical and electrical control over defects.