**Head: **Prof. Dr. Alexey Ustinov

Superconducting quantum circuits are among the most promising solid state candidates as building elements for quantum computers. Superconducting quantum devices are well suited for applications ranging from basic research over to applied disciplines like material characterization, medical imaging to quantum computers. Using well-established integrated-circuit processing techniques, as developed and brought to perfection for semiconductor technology, complex micron-sized quantum circuits can be scaled up to a large number of qubits.

In recent years, impressive progress has been made to address, control, readout, and scale superconducting qubits, resulting, for example, in the proof of the violation of Bell's inequality, measurements of three qubit entanglement, quantum non-demolition readout, creation of arbitrary photon states, and circuit quantum electrodynamics in strong and ultra-strong coupling regimes.

In our working group we simulate, design, fabricate and measure superconducting qubits based on various working principles. The qubits are controlled by DC flux to chance their level splitting (|0> and |1> state) and by microwave pulses to excite them. As the typical energy splitting between the qubit states is about several GHz, the temperature of the circuit has to be kept low enough (10 GHz <-> 0.5 K) to avoid thermal population of the excited states.