GEOMDISS Results

First year achievements

Second year achievements

Third year achievements


  1. Experimental observation of Berry’s of the harmonic oscillator (cavity) states in the dispersive regime [1] (see first figure below).
  2. Theoretical proposal of non-Abilian holonomic gates in a 3-qubit setup.
  3. Current detection improved for Cooper-pair pumping experiments.
  4. Theory of Cooper pair pumping in presence of dissipation extended. Analysis in Floquet basis turns out to be most adequate.
  5. New theoretical results on charge and spin pumping in quantum dots with electron-electron interactions.
  6. Role of the Berry phase understood in connection with mesoscopic magnetization in multi-electron interacting quantum dots.
  7. New topological insulator investigated in which the edge states are in the bulk gap. Promising potential for spin pumping identified.

 

cavity_phase.png

  
(A) Circular trajectories of the resonator coherent state for the two qubit states have different sizes (left), due to a qubit-dependent shift of the resonator response function (right). The phase difference measured in the experiment is given by the area ΔA enclosed between the two trajectories.
(B) The different path shapes used in the experiment and the corresponding geometric phases relative to the phase for the circular path. Indicated is the typical maximum photon number n ≈ 20.


Nonadiabatic Cooper pair pump consisting of a superconducting island shown as blue bar separated by a single Josephson junction and a SQUID. The energy levels of the island are controlled by the dc gate and the high frequency pulse gate.

   CooperPairPump.png