Malay Singh

Offered Bachelor’s or Master’s Theses Topics

Dynamical decoupling and noise spectroscopy with superconducting qubits

The characterization and mitigation of decoherence sources in qubits is crucial for quantum computing applications. Decoherence of a quantum superposition state arises from the interaction between the system and the uncontrolled degrees of freedom in its environment. The qubit decoherence is characterized by two rates: a longitudinal relaxation rate Γ1 due to the exchange of energy with the environment, and a transverse relaxation rate Γ2 = Γ1/2 + Γϕ which contains the pure dephasing rate Γϕ. Irreversible energy relaxation can only be mitigated by reducing the amount of environmental noise, reducing the qubit’s internal sensitivity to that noise, or through multi-qubit encoding and error correction protocols. In contrast, dephasing is in principle reversible and can be refocused dynamically through the application of coherent control pulse methods. In this work we are going to investigate different sources of noise and decoherence and how dynamical-decoupling techniques such as CPMG can change the dephasing effects of low-frequency noise on a superconducting qubit.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Stefan Filipp