Electron spins in silicon quantum dots are excellent qubits due to their long coherence times, scalability, and compatibility with advanced semiconductor technology. Even though single- and two-qubit gates with fidelities above 99% have been achieved in Si spin qubits, charge noise in the semiconductor environment still hinders gate fidelities. Despite the importance of charge noise, key questions like what specific defects cause the noise, where they are in the device, and how they are thermalized, remain unanswered. I will discuss recent work probing individual two-level fluctuators (TLFs) in Si/SiGe quantum dots via simple transport measurements. We find that the TLFs depend sensitively on gate voltage and temperature. We also find that the TLFs are likely not described by a model involving isolated dipole fluctuators coupled to a phonon bath, and that current through the quantum dot appears to heat the TLFs. These measurements open up new pathways for detailed characterization of noise sources in spin qubits.

This event starts at 3:30pm with refreshments, followed at 3:45pm by a short presentation by Ben Harpt (PhD student Mark Eriksson group) titled "Longitudinal electron-photon coupling in a quantum-dot qubit: expanding the toolbox for quantum engineers". The invited presentation starts at 4pm.