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Theory of Superconducting and Electromagnetic Properties of Some Nanostructured Materials David Stroud, Ohio State University, DMR 0413395. RESEARCH HIGHLIGHT: COOLING OF A NANOMECHANICAL OSCILLATOR COUPLED TO A SMALL JOSEPHSON JUNCTION.
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Theory of Superconducting and Electromagnetic Properties of Some Nanostructured MaterialsDavid Stroud, Ohio State University, DMR 0413395 RESEARCH HIGHLIGHT: COOLING OF A NANOMECHANICAL OSCILLATOR COUPLED TO A SMALL JOSEPHSON JUNCTION. Strange quantum-mechanical effects can be seen in nanomechanical oscillators when they are cooled sufficiently. Our calculations show that this cooling can be greatly enhanced if the oscillator is coupledto a small superconducting device called a Josephson junction. The enhancement is shown at upperright. The upper blueline shows the oscillator by itself. The redline shows the same oscillator coupled to the junction (fast cooling). Top right: oscillator coolsfaster when coupled to junction. Lower right: junction coolsmore slowly when coupled to oscillator. (Above) Schematic of nanomechanical oscillator (thick black bar) coupled to small Josephsonjunction (X on top right). Electronics cause oscillator and junction to exchange energy.
Applications: Can be used in a device for quantumcomputation. Many nanoscale Josephson junctions coupled to nanomechanical oscillators can be valuable in ultrafast computing. Nanomechanical oscillators should show ``macroscopicquantumbehavior’’ (quantum behavior of objects containing many atoms) if sufficiently cold. Seeing such behavior will confirm basic quantum principles. References: R. P. Tiwari and D. Stroud, Phys. Rev. B77, 214520 (2008) and in preparation. Contributions to education:Seven grad students (D. Valdez-Balderas, I. Tornes, K. Kim, V. Guttal, R. P. Tiwari, C. Porter, K. Kobayashi), two undergrads [B. Chen (Harvard); S. Natu (Ohio Wesleyan)] contributed to this work. Ivan Tornes is now a researcher at Battelle, D. Valdez-Balderas and K. Kim have postdocs at Rochester and Maryland. Work done under this grant was included in courses on Quantum Computation,Condensed Matter Physics, and Electromagnetism. Notes for all of these are posted on the web. Theory of Superconducting and Electromagnetic Properties of Some Nanostructured Materials David Stroud, Ohio State University, DMR 0413395