Because of non-zero friction of the Brownian motion a work should be performed at this first mesoscopic phenomenon discovered as long ago as in the beginning of 19 century and described as one of the fluctuation phenomena in the beginning of 20 century [1]. The progress of modern nano-technology and the discovery of the direct Brownian motion [2] allow to use this phenomenon for an useful work.

Nano-scale quantum power source can be made on the base of a system of inhomogeneous mesoscopic superconducting loops [3]. The power of the persistent voltage predicted [2] and observed [4] on segment of such loop is not random and can be added in contrast to the random power of the Nyquist's (Johnson's) noise [5]. Therefore a power value acceptable for some application can be obtained by means of the system of great number of nano-scale loops in spite of very weak power of any fluctuations, at T = 100 K. The modern methods of nano-technology allow to make the system of 10 loops on an area . Such system of high-Tc superconductor loops can give the dc power up to 1 Wt. The power can be increased in many times by the use of multi-layer technology. References:

1. R.P. Feynman, R.B. Leighton and M. Sands. The Feynman Lectures on Physics, v I. Reading, Massachusetts: Addison-Wesley Publishing Company, 1963.
2. A.V. Nikulov, Phys. Rev. B 64, 012505 (2001)
3. A.V. Nikulov, Abstracts of NATO ASI ``Quantum Mesoscopic Phenomena and Mesoscopic Devices in Microelectronics'' Ankara, Turkey, p.105, (1999); Proceedings of the Symposium on Micro- and Nanocryogenics, Jyvaskyla, Finland, p.68, (1999); in SUPERMATerials, Eds. R.Cloots et al. Kluwer Academic Publishers, p.183 (2000); V.V. Aristov and A.V. Nikulov, Abstracts of Fourth APAM Topical Seminar, Seoul, Korea, p.25, (2000).
4. S.V. Dubonos, V.I. Kuznetsov, A.V. Nikulov and V.A.Tulin, Abstracts of the Russian Conference ``Micro- and Nano-Electronics'', Lipki, Moscow Region, P2-25, (2001).
5. H.Nyquist, Phys.Rev. 32, 110 (1928); J.B.Johnson, idid. 32, 97 (1928)