Quantum Effects in Nano-Devices: Measuring a Single Quantum System

Quantum nano-structures are likely to become primary components of future electronic devices. Presently the majority of these structures, such as nano-mechanical resonators, semiconductor quantum dots, single electron transistors, and similar low dimensional structures, exist as prototypes in research laboratories or just being contemplated. Practical realization of quantum devices faces a number of challenges. Besides apparent difficulties with device fabrication, which typically requires micro– to nanometer scale resolution, there are numerous fundamental problems. These problems include phase relaxation (decoherence) that erodes operation of a quantum device as well as the problems of control, such as manipulation and measurement of the quantum states in a device. However, the benefits from the successful implementation of these devices can be enormous and have to do with the fact that, in their operation, the quantum devices utilize the fundamental properties of nature that do not have direct analogs in classical physics.