Quantum Coherent Electron-Phonon Nanolaboratories
Final rept. 1 Jun 1989-31 May 2003
CALIFORNIA UNIV REGENTS SANTA BARBARA OFFICE OF RESEARCH
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This project was aimed at creating mechanically suspended nanostructures that include active electronic devices, with the goal of achieving coherence between electrons and vibrational phonons. We pursued separately the use of metal tunnel junctions 515 tunnel junctions and single-electron transistors, SETs, and electrostatically defined double quantum dots, as the electronic system. We performed cryogenic measurements with varying degrees of success. Due to unanticipated difficulties, the focus shifted direction several times. Our most successful implementation was the use of an SET coupled to the vibrational motion of a doubly-clamped 100 MHz flexural resonator, with which we achieved a displacement sensitivity roughly 100 times the quantum limit of motion. A ten times higher frequency resonator, at I GHz, could be detected at 10 times the quantum limit. We believe further improvement in the sensitivity and noise of the displacement sensor is possible. Other areas of research, such as using double-quantum dots, did not prove as illuminating or useful direct, resonant coupling as observed by dc current-voltage measurements did not reveal the hoped-for signatures of resonant coupling. There are a number of reasons as to why this may be, and further work might further elucidate the physics.
- Electricity and Magnetism
- Quantum Theory and Relativity
- Radiofrequency Wave Propagation