Superconducting quantum circuits are among the most promising solid state candidates as building elements for quantum computers due to their ultra-low dissipation, inherent to superconductors.

A short introduction is here (in german, from *Helmholtz Perspektiven March-April 2014*): Was ist eigentlich ein Quantencomputer?

In general, superconducting quantum devices have unique properties like magnetic field resolution, coherence, scalability, and implementation. They are well suited for applications ranging from basic research over to applied disciplines like material characterization, medical imaging to quantum computers. Superconducting qubits fulfill the DiVincenzo criteria for a scalable quantum computer. Using integrated-circuit processing techniques such as used for digital and rapid single flux quantum (RSFQ) circuits, complex micron-sized quantum circuits can be scaled up to a large number of qubits.

In ten 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.

At KIT, we simulate, design, fabricate and measure **superconducting qubits** - including varieties of **phase, flux and transmon qubits**. 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.

**Our research interests range from new readout techniques, qubit designs, resonant circuit material science to quantum metamaterials and quantum simulation**.Starting from circuit simulation we implement the quantum chips using local facilities (Center for Functional Nanostructures) before measuring in a dilution refrigerator.

**Students **are always welcome for** Bachelor, Master or PhD positions**.

We use** quantum and electromagnetic circuit simulation, nanotechnology, milliKelvin cryostats, and transport and microwave setups** for our research.

Here is a laymen presentation of our research (Experimentelle Realisierung des Quantencomputers).

The projects depend on the current state of our research. **In case you are interested ****feel free to contact us**.

Contact: Dr. Martin Weides