ERC FUNDED PROJECTS

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.

1 377 000 €

Start date: 2008-06-01, End date: 2013-05-31

The purpose of this proposal is to investigate from various perspectives some equidistribution problems associated with homogeneous spaces of arithmetic type: a typical problem (basically solved) is the distribution of the set of representations of a large integer by an integral quadratic form. Another harder problem is the study of the distribution of special points on Shimura varieties. In a different direction (linked with quantum chaos), the study of the concentration of Laplacian (Maass) eigenforms or of sections of holomorphic bundles is related to similar problems. Given X such a space and G>L the underlying algebraic group and its corresponding lattice L, the above questions boil down to studying the distribution of H-orbits x.H (or more generally H-invariant measures)on the quotient L\G for some subgroups H. This question may be studied different methods: Harmonic Analysis (HA): given a function f on L\G one studies the period integral of f along x.H. This may be done by automorphic methods. In favorable circumstances, the above periods are related to L-functions which one may hope to treat by methods from analytic number theory (the subconvexity problem). Ergodic Theory (ET): one studies the properties of weak*-limits of the measures supported by x.H using rigidity techniques: depending on the nature of H, one might use either rigidity of unipotent actions or the more recent rigidity results for torus actions in rank >1. In fact, HA and ET are intertwined and complementary : the use of ET in this context require a substantial input from number theory and HA, while ET lead to a soft understanding of several features of HA. In addition, the Langlands correspondence principle make it possible to pass from one group G to another. Based on earlier experience, our goal is to develop these interactions systematically and to develop new approaches to outstanding arithmetic problems :eg. the subconvexity problem or the Andre/Oort conjecture.

866 000 €

Start date: 2008-12-01, End date: 2013-11-30

This project aims at developing theoretical and empirical research on the structural transformation that accompanies economic development and on the determinants of its success or failure. This transformation involves changes in policies, institutions, and even preferences and social hierarchies. The project consists of four subprojects. Since China represents the most spectacular ongoing episode of economic transition, four of them focus on the Chinese experience, while the remaining ones address general issues in growth and development. The first subproject analyses some puzzling features of China's recent growth experience, such as the coexistence of high growth with increasing capital export, and the falling labour share, with the aid of a theory which emphasises the efficiency gains associated with the reallocation between firms of different productivity. Since changes in income distribution are an important element, and a concern, of the Chinese transition, the three following subprojects focus, respectively, on the crisis of the system of old age insurance, the effects of the rise of the middle class, and the introduction of special economic zones in the 1980s. Two subprojects study different aspects of competition policy in development. The first one focuses on intellectual property right protection, emphasising the link between innovation, technology adoption and human capital accumulation. The second one studies the coordinating role of industrial policy and how its scope changes with development. The last two subprojects focus on culture. The diffusion of preferences and values that foster cooperation rather than conflict is no less important than incentives for technology adoption. Likewise, the rise of an "entrepreneurial spirit" is an engine of growth in the development transition. We plan to study the emergence and cultural transmission of preferences that are conducive to economic growth, and how they interact with the process of structural change.

1 599 996 €

Start date: 2009-01-01, End date: 2014-06-30

Analogous to quality control checks along the assembly line in industrial manufacturing processes, cells possess multiple quality control systems that ensure accurate expression of the genetic information throughout the intricate chain of biochemical reactions. “Nonsense-mediated mRNA decay” (NMD) represents a quality control mechanism that recognizes and degrades mRNAs of which the protein coding sequence is truncated by the presence of a premature termination codon (PTC). By eliminating these defective mRNAs with crippled protein-coding capacity, NMD substantially reduces the synthesis of potentially deleterious truncated proteins. Given that 30 % of all known disease-causing mutations in humans lead to the production of a nonsense mRNA, NMD serves as an important modulator of the clinical manifestations of genetic diseases, and manipulating NMD therefore represents a promising strategy for future therapies of many genetic disorders. However, the underlying molecular mechanisms of NMD are currently not well understood. One goal of our research is to understand at the molecular level how PTCs are recognized and distinguished from correct termination codons and how this recognition of nonsense mRNAs subsequently triggers their rapid degradation. In addition to triggering NMD, we have recently discovered that PTCs in certain immunoglobulin genes can also lead to the transcriptional silencing of the corresponding gene. We now search for the biological relevance of this novel quality control mechanism termed “nonsense-mediated transcriptional gene silencing” (NMTGS) and want to identify the involved molecules and their interactions. Using mainly mammalian cell cultures, we study the effect on the expression of engineered NMD and NMTGS reporter genes upon various treatments of the cells. State-of-the-art biochemical and molecular biology techniques are employed with the goal to further our understanding of these processes and their regulation at the molecular level.

1 300 000 €

Start date: 2008-06-01, End date: 2013-05-31