Objective Macroscopic control of quantum states is a major theme in much of modern physics because quantum coherence enables study of fundamental physics and has promising applications for quantum information processing. The potential significance of quantum computing is recognized well beyond the physics community. For electron spins in GaAs quantum dots, it has become clear that decoherence caused by interactions with the nuclear spins is a major challenge. We propose to investigate and reduce hyperfine induced decoherence with two complementary approaches: nuclear spin state narrowing and nuclear spin polarization. We propose a new projective state narrowing technique: a large, Coulomb blockaded dot measures the qubit nuclear ensemble, resulting in enhanced spin coherence times. Further, mediated by an interacting 2D electron gas via hyperfine interaction, a low temperature nuclear ferromagnetic spin state was predicted, which we propose to investigate using a quantum point contact as a nuclear polarization detector. Estimates indicate that the nuclear ferromagnetic transition occurs in the sub-Millikelvin range, well below already hard to reach temperatures around 10 mK. However, the exciting combination of interacting electron and nuclear spin physics as well as applications in spin qubits give ample incentive to strive for sub-Millikelvin temperatures in nanostructures. We propose to build a novel type of nuclear demagnetization refrigerator aiming to reach electron temperatures of 0.1 mK in semiconductor nanostructures. This interdisciplinary project combines Microkelvin and nanophysics, going well beyond the status quo. It is a challenging project that could be the beginning of a new era of coherent spin physics with unprecedented quantum control. This project requires a several year commitment and a team of two graduate students plus one postdoctoral fellow. Fields of science engineering and technologyelectrical engineering, electronic engineering, information engineeringelectronic engineeringcomputer hardwarequantum computersnatural sciencesphysical scienceselectromagnetism and electronicssemiconductivity Keywords low temperature physics mesoscopic physics quantum coherence and computation spin physics Programme(s) FP7-IDEAS-ERC - Specific programme: "Ideas" implementing the Seventh Framework Programme of the European Community for research, technological development and demonstration activities (2007 to 2013) Topic(s) ERC-SG-PE3 - ERC Starting Grant - Condensed matter physics Call for proposal ERC-2007-StG See other projects for this call Funding Scheme ERC-SG - ERC Starting Grant Coordinator UNIVERSITAT BASEL Address Petersplatz 1 4051 Basel Switzerland See on map Region Schweiz/Suisse/Svizzera Nordwestschweiz Basel-Stadt Activity type Higher or Secondary Education Establishments Principal investigator Dominik Max Zumbühl (Prof.) Administrative Contact Kurt Kamber (Dr.) Links Contact the organisation Opens in new window Website Opens in new window EU contribution € 1 377 000,00 Beneficiaries (1) Sort alphabetically Sort by EU Contribution Expand all Collapse all UNIVERSITAT BASEL Switzerland EU contribution € 1 377 000,00 Address Petersplatz 1 4051 Basel See on map Region Schweiz/Suisse/Svizzera Nordwestschweiz Basel-Stadt Activity type Higher or Secondary Education Establishments Principal investigator Dominik Max Zumbühl (Prof.) Administrative Contact Kurt Kamber (Dr.) Links Contact the organisation Opens in new window Website Opens in new window
