EventDetails

Speaker:
Prof. Dr. Klaus Ensslin, ETH Zürich

Charge qubits in semiconductors are straightforward to realize using quantum dots, but they suffer from short coherence times. Spin qubits consisting of a single spin (electron) in a quantum dot or two electrons in two quantum dots (singlet-triplet) offer larger coherence times, but are more difficult to manipulate and to couple to superconducting microwave resonators. Using quantum dots in AlGaAs heterostructures we prepare so-called resonant exchange qubits, which consist of three electrons in three quantum dots. The spin configuration in the triple dot systems can be tuned by exchange interactions controlled by a set of gate voltages. This way we demonstrate the strong coupling regime between a spin qubit and a microwave photon. In another configuration one can place a single electron in three tunnel-coupled quantum dots and couple a microwave resonator to the quadrupole moment of the charge configuration rather than the diploe moment. Other interesting dot, charge and spin configurations can be realized in the well-controlled AlGaAs system thus using qubit systems to probe new physics. Novel 2D material systems such as bilayer graphene and TMDCs offer prospects for other complex charge and spin qubits.