Persistent control of a superconducting qubit by stroboscopic measurement feedback

Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists in monitoring an observable (temperature, blood-glucose level...) and reacting on its controllers (heater power, insulin amount ...). In the quantum domain, there is a change of paradigm in feedback since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement based feedback. The protocol benefits from the long coherence time ($T_2>10 \mu$s) of the 3D transmon qubit, the high efficiency (82%) of the phase preserving Josephson amplifier, and fast electronics ensuring less than 500 ns delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which does not go through pointer states, the average fidelity reaches 75%. Incidentally, we demonstrate a fast reset protocol allowing to cool a 3D transmon qubit down to 0.6% in the excited state.Comment: 7 pages, 3 figures and 1 table. Supplementary information available as an ancilla fil

Perceived Personal and Social Competence: Development of Valid and Reliable Measures

During the last 20 years, youth programming has shifted from risk reduction to youth development. While numerous instruments exist to measure selected individual characteristics/competencies among youth, a comprehensive instrument to measure four constructs of personal and social skills could not be identified. The purpose of this study was to develop four assessment instruments to measure perceived personal/social competence. Specifically, this study focused on identifying items to measure: (a) intrapersonal skills, (b) interpersonal skills, (c) coping skills, and (d) judgment skills. A Delphi panel of nine professionals in health education, youth development programming, and instrument development established content validity. Readability of the four scales ranged from 3.82 to 6.43 using the Gunning Fog Index. Internal consistency reliability was calculated for intrapersonal skills (α=.96), interpersonal skills (α=.91), coping skills (α=.89), and judgment skills (α=.91). Program planners and evaluators could use one or all four scales (i.e., intrapersonal, interpersonal, coping, judgment skills) to assess short-term impact of their youth development programs

Tropical Greenhouses: A Great Opportunity for Small Farmers Drivers and barriers for agricultural innovation

Delft Centre for Entrepreneurshi

Giant optical anisotropy in a single InAs quantum dot

International audienc

Giant optical anisotropy in single InAs quantum dots

communication oraleInternational audienc

Persistent control of a superconducting qubit by stroboscopic measurement feedback

International audienc

Giant optical anisotropy in a single InAs/GaAs quantum dot

posterInternational audienc