Physics

Waving Current Standards

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Science  21 May 2004:
Vol. 304, Issue 5674, pp. 1079
DOI: 10.1126/science.304.5674.1079c

The ability to pump a discrete and known amount of charge around a system is the basis for quantum current standards such as those built on single-electron transistors and electron turnstile devices. These devices incorporate gated barriers that open and close, allowing for the flow of quantized charge, but generally operate at low frequencies and require complicated electronics to transport and sense the small flowing packets of discrete charge.

Ebbecke et al. introduce a technique for the pumping of quantized amounts of charge through a quantum dot using surface acoustic waves (SAWs). Without the need for an applied bias, the SAWs effectively deform the confining potential of the quantum dot, so that discrete packets of charge squeeze through it in each cycle. Being somewhat simpler and able to operate at high frequency (3 GHz here), the technique should find application in the developing field of quantum current standards. — ISO

Appl. Phys. Lett. 84, 4319 (2004).

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