The number-phase uncertainty principle and fundamental limits of quantum interference devices
✍ Scribed by Akira Shimizu; Hiroyuki Sakaki
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 618 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
We consider a mesoscopic conductor, in which a quantum interference current J can be modulated by an external "input" variable I. The Z is either a classical variable such as a gate voltage, or a quantum-mechanical one such as a photon number. Assuming that the conductor is fabricated perfcdly, i.e., no unintentional scatterers are present, we evaluate the fluctuation of .Z as a function of I, by formulating a measurement of .Z as an electroncounting process. The fluctuation is shown to be a general noise in quantum mechanics, which is related with the number-phase uncertainty principle. The noise is also shown to determine the fundamental limifs of performances of quantum interference devices. The explicit formulas for the limits are derived