Qubit Coherence and Fidelity
In this video, Menno presents quantum coherence of a qubit and fidelity of single qubit gates.
Main takeaways
- Quantum coherence can be extended with material development (reducing hyperfine interactions for example) or pulses engineering (Hahn echo or CMPG ).
- In Ge, quantum coherences are longer at low magnetic field with T2 up to 0.5ms but qubit operations are faster at higher magnetic field.
- In the hyperfine limited regime, the dephasing time of natural germanium is 6us.
- Randomised benchmarking is a random series of Clifford gate to probe the performance of single qubit gates. Minimum fidelity requirement for quantum algorithm is 99%.
Further thinking
How can we improve dephasing time of a qubit?
a. By pulse engineering
b. By material engineering
c. By adding a nanomagnet
Further reading
Semiconductor spin qubits review https://arxiv.org/pdf/2112.08863.pdf