Princeton Center for Complex Materials

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****Nontechnical abstract****The interdisciplinary research in the MRSEC at Princeton is focused on three directions in materials research. The first exploits recent advances in physics and chemistry to uncover novel "topological" quantum properties of electrons in semiconductors. The research is promising for enabling future electronics with ultralow heat dissipation, and enabling novel approaches to quantum computing. In the second direction, the researchers combine two new technologies that enable the growth of very thin polymer films with specialized physical properties critical for applications in many industries. The third direction seeks to control and manipulate the spin of a single electron trapped in an ultrathin nanowire. Advances will lead to logic elements for quantum computing as well as a new class of broadly tunable lasers. The researchers participate in a broad array of education projects. Each summer, 20 undergraduates, selected from over 400 applicants nationwide, engage in supervised research in preparation for graduate school in science and engineering. In addition, the researchers host 18 high-school and 30 middle-school students from Central High, Trenton, for a rigorous 3-week science-camp (PUMA). The PUMA alumni have achieved a high-school graduation rate of 100%, with most going on to college. In addition, the researchers hold 8 one-day Science fairs each year (some co-organized with the town library) which attract from 300 to 800 K-12 students and their parents to campus. ****Technical abstract****In the first of 3 projects, researchers seek to expand the search for novel topological quantum properties of electrons in insulators, semiconductors and semimetals. Currently, the long-established Bloch theory of crystalline solids is undergoing revision because of topological principles neglected in Bloch theory. Semiconductors in which the energy gap is "inverted" (relative to the atomic limit) exhibit surface states occupied by massless Dirac fermions. Using scanning tunneling microscopy, transport and photoemission experiments, researchers will test key predictions of the new perspective, and search for new topological phases and excitations (e.g. Majorana fermions). In the second project, researchers will apply a laser-ablation technique called MAPLE to grow and investigate ultrathin polymer films deposited under novel conditions that dramatically raise the glass-transition temperature. Combining expertise in fluorescence, nanoscale imaging and simulation, they will address the technologically important issue of why the thermodynamic properties (e.g. the glass transition) of confined polymers differ dramatically from those in bulk polymers. Researchers in the third project will address a challenging problem in the quest for quantum computing, namely how to couple well-separated qubits without losing quantum information. Applying recent advances, they will coherently couple spin qubits using microwave photons trapped in a high-Q superconducting resonator. A serendipitous benefit is the discovery of lasing action. In a parallel effort, experiments to achieve very long spin coherence lifetimes in isotopically pure silicon are proposed.