Nummerical Optimization of Control of Multiple Carbon Qubits near a Nitrogen-Vacancy Center
T.H. Dikland (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Tim Hugo Taminiau – Mentor
NV Budko – Mentor
JLA Dubbeldam – Graduation committee member
IM Blanter – Graduation committee member
B. van den Dries – Graduation committee member
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Abstract
The NV-center in diamond is a promising system for quantum information processing. The typical qubits are the electron spin in the NV-center and the surrounding 13C nuclear spins. Fast and precise control of many 13C spins is desirable but challenging due to crosstalk. Crosstalk is the unwanted effect of a control pulse on the other qubits. The coupled NV-13C system is explored, and numerical techniques to optimize the control of multiple and single qubits are used. In this report the effect of the Bloch-Siegert shift in the weak driving regime is investigated first. This is done by studying the effect of a π-pulse when two carbon qubits are driven at the same time on resonance. It turns out that in this weak driving regime the effect of the off resonance is very small, and changes the fidelity not more than 0.3%. Furthermore the effect of a square πpulse on 4 nearby qubits is studied. If the pulse is not optimized (thus square), the pulse cannot be done in less than 100µs while retaining at least 99% fidelity. By optimizing the envelope of the driving field using constrained optimization the pulse can be done in 22µs while retaining at least 99% fidelity.