GEOMDISS Results
First year achievements |
Second year achievements |
Third year achievements |
- Experimental observation of Berry’s phase in cavity QED setup with the “Transmon” qubit (see figure below).
- Theory of Berry’s phases in multi-level qubits. The theory qualitatively describes the experiment, although quantitative disagreement remains.
- First experiments showing adiabatic-non-adiabatic crossover in Cooper pair pumping.
- Theory of Cooper pair pumping in presence of dissipation. We predict extra robustness due to low temperature environment. [1]
- First theoretical results on charge and spin pumping in quantum dots with electron-electron interactions.
(a) Schematic of the measurement setup. (b) Envelopes of the microwave pulses used in a geometric phase measurement. The measurement consists of a series of resonant (ωα) and off-resonant (ωα) pulses applied either on the x-quadrature (blue) or the y-quadrature (green). The geometric phase is generated by the adiabatic evolution between the resonant pulses. (c) Geometric phase acquired by the qubit vs. solid angle spanned by the path traced out by the qubit. The results of the measurement described in b (dots) are superimposed with the theoretical curves obtained with second-order perturbation theory (continuous lines) and Berry’s prediction for a two-level-system (grey dashed line). The off-resonant pulses were applied with detuning Δ=50 MHz (green) and Δ=−50 MHz (blue).