QDev Seminar: Lukasz Cywinski

Decoherence of spin qubits based on quantum dots is often (especially for III-V dots) dominated by interaction of the electron spin with the nuclear spins.  In the case of a single qubit this process is quite well understood, and the established theoretical approaches can be applied to quantum states of more than one qubit. I will present calculations of dynamics of entanglement decay of two single-spin qubits, paying special attention to the features which distinguish this process from decoherence of a singlet-triplet qubit (which is also built out of two electrons localized in two quantum dots). The role of spatial symmetries and correlations of noise will also be discussed, and a method of using two qubits to sense the spatio-temporal correlations of external noise will be outlined.