Theory of Pulsed Spectroscopy in Quantum Dots: Interdot Dynamics

Understanding the energy structure and dynamics of excited states in quantum-dot qubits is critical for device design and operation. Incoherent methods for probing these quantities typically call for loading from neighboring baths or applying large external magnetic or RF fields. These methods may be problematic if they require operating conditions far from the intended qubit environment. We have developed a technique to characterize these quantities using typical tune-up conditions, relying on the incoherent dynamics of interdot charge transitions. In the first half of this two-part talk, we examine theoretically how tunneling, dephasing, and detuning-dependent relaxation affect the time-dependent populations near charge transition points and allow excited states to be resolved. We compare these expectations to experimental results in Si/SiGe quantum dots. Potential connections to the dynamics relevant for spin qubit readout are considered.