This project describes a new approach to study micro- and nano- fabricated structures whose physical dimensions new effects originating because the wavelength of the quantum excitations have dimensions of the order of the physical structures involved. By exploiting the ability to fabricate free-standing metallic microstructures with dimensions as small as 25 nm, it is possible to decouple these microstructures from the bulk phonons emanating from the substrate. This permits the phonon density of states to be controlled systematically, and thus provides a unique opportunity to study the electrical and lattice properties of low dimensional systems. The consequences of low phonon dimensionality on the electron-phonon interaction will be investigated by measurements of electron inelastic scattering and thermal transport properties of the electron gas. Interference properties of superconductors will also be studied using materials prepared by a similar fabrication process. This should allow the injection of quasiparticles into the superconductor, as well as superconducting pairs into the adjacent normal metal. This can be done with a spatial resolution smaller than the coherence length, thus providing a route to "imaging" proximity effects in junctions and, possibly, providing a determination of the relation between superconducting transition temperatures and characteristic lengths in materials.
