Walther-Meißner-Institute

 

PhD on the generation and detection of quantum correlations in circuit QED systems

Prof Rudolf Gross group at the Walther-Meißner-Institut for Low Temperature Research, Walther-Meißner-Str. 8, 85748 Garching, Germany

Job description

Quantum correlations are of utmost importance for quantum simulations, quantum information processing, and quantum cryptography. Towards these goals, superconducting quantum circuits acting as artificial atoms or, alternatively, microwave photon boxes, have produced exciting progress in recent years. Being formally equivalent to quantum optical systems, superconducting quantum circuits offer potential scalability, huge design flexibility, and impressive coupling strengths. These properties make them ideal candidates for investigating quantum effects.

In this work, the Walther Meißner Institute (WMI) aims at generating propagating microwave signals at the single photon level by using superconducting multi-resonator structures known from circuit quantum electrodynamics (QED). For the detection of such weak microwave signals, single photon “click” detectors well-established in the optical regime are currently not available. Instead, off-the shelf linear amplifiers can be used. To overcome the problem of noise added by these amplifiers, WMI has recently developed a signal recovery method: the signal is split by a microwave beam splitter and the uncorrelated noise of the two amplification chains is suppressed by cross-correlating the signals and averaging.  The ESR at WMI will start with two-resonator systems, which will be used to experimentally confirm predictions made by our collaborators regarding the generation of entanglement as a function of temperature. In a next step, the ESR should investigate quantum microwave states generated in a setup, where an artificial atom mediates switchable coupling between two superconducting transmission line resonators. Finally, also systems with more than two resonators should be studied. The experiments will be performed in a dilution refrigerator at millikelvin temperatures. The technological basis for the realization of the superconducting quantum circuits and detecting quantum correlations is already well-established.

Profile

You have a diploma/master in Material Sciences/Solid State Physics and experience in one or more of the following fields: Josephson devices, quantum optics, solid state quantum circuits, thin film technology, low-temperature techniques, microwave devices/technology. Fluency in German is a plus, English is mandatory.

About the Walther-Meißner-Institute

The research program of Walther-Meißner-Institute for Low Temperature Research (WMI) is focused on fundamental and applied research in the field of low temperature solid-state physics with the main focus on superconductivity and superfluidity, magnetism and spin electronics, mesoscopic systems and nanotechnology, quantum information processing, as well as on the general properties of metallic systems at low and very low temperatures. It also conducts applied research into methods of generating and using low temperatures. With respect to materials the activities of WMI are focused on superconducting and magnetic materials, both in bulk and thin films.