Non-equilibrium Phonon Generation and Detection in Microstructure Devices

We demonstrate a method to excite locally a controllable, non-thermal distribution of acoustic phonon modes ranging from 0 to ∼200 GHz in a silicon microstructure, by decay of excited quasiparticle states in an attached superconducting tunnel junction (STJ). The phonons transiting the structure ballistically are detected by a second STJ, allowing comparison of direct with indirect transport pathways. This method may be applied to study how different phonon modes contribute to the thermal conductivity of nanostructuresThe authors thank R. B. Van Dover, J. Blakely, S. Baker, K. Schwab, and Cornell LASSP for loan of key equipment, and L. Spietz for photolithography recipes. We thank R. B. Van Dover, K. Schwab, E. Smith, J. Parpia, D. Ralph, B. Plourde, M. Blencowe, D. Westly, R. Pohl, P. Berberich, and C. Mellor for helpful discussions and thank D. Toledo, J. Chang and A. Lin for help with apparatus. The authors acknowledge funding from the National Science Foundation (NSF) (DMR 0520404) and Department of Energy (DOE) (DE-SC0001086). This publication is based on work supported in part by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). This work was performed in part at the Cornell NanoScale Facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation (Grant ECS-0335765

Solid State Systems for Electron Electric Dipole Moment and other Fundamental Measurements

In 1968, F.L. Shapiro published the suggestion that one could search for an electron EDM by applying a strong electric field to a substance that has an unpaired electron spin; at low temperature, the EDM interaction would lead to a net sample magnetization that can be detected with a SQUID magnetometer. One experimental EDM search based on this technique was published, and for a number of reasons including high sample conductivity, high operating temperature, and limited SQUID technology, the result was not particularly sensitive compared to other experiments in the late 1970's. Advances in SQUID and conventional magnetometery had led us to reconsider this type of experiment, which can be extended to searches and tests other than EDMs (e.g., test of Lorentz invariance). In addition, the complementary measurement of an EDM-induced sample electric polarization due to application of a magnetic field to a paramagnetic sample might be effective using modern ultrasensitive charge measurement techniques. A possible paramagnetic material is Gd-substituted YIG which has very low conductivity and a net enhancement (atomic enhancement times crystal screening) of order unity. Use of a reasonable volume (100's of cc) sample of this material at 50 mK and 10 kV/cm might yield an electron EDM sensitivity of $10^{-33}$ e cm or better, a factor of $10^6$ improvement over current experimental limits.Comment: 6 pages. Prepared for ITAMP workshop on fundamental physics that was to be held Sept 20-22 2001 in Cambride, MA, but was canceled due to terrorist attack on U.S New version incorporates a number of small changes, most notably the scaling of the sensitivity of the Faraday magnetometer with linewidth is now treated in a saner fashion. The possibility of operating at an even lower temperarture, say 10 microkelvin, is also discusse