| 摘要 |
A nanofabricated logic device, operable at multiple (more than two) logic levels comprises asymmetrically coupled quantum point contacts (QPC1, QPC2) provided with respective sources (A, B) and drains (D, C) and a coupling region (LT) between gate electrodes (GT1, GT2). The quantum mechanical carrier wavefunction in the region of QPC1, 2 is spatially asmmetric with alternate quantised energy levels lying either in QPC1, or QPC2, so that by changing the energy level, the conductance of the device can be switched between multiple stable conductance levels. The device can be used to provide a multilevel output switched in response to terahertz pulses provided by an array of optical detectors (30). |
