Department of Physics
Research, teaching and outreach in Physics at UW–Madison

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R. G. Herb Condensed Matter Seminars
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Electronic refrigeration of two-dimensional electron gases
Date: Friday, June 5th
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Jon Prance, Cambridge University
Abstract: Two-dimensional electron gases (2DEGs) in semiconductors are the basis for studies of a wide range of physical phenomena, particularly at sub-kelvin temperatures. However, efforts to cool these systems much below 10 mK quickly encounter the problems of reduced thermal conductivities and the necessity for increasingly complex refrigeration techniques.

One possible solution is direct electronic refrigeration of the 2DEG. The Quantum Dot Refrigerator (first proposed by Edwards et al.[1]) employs energy-selective tunneling through a pair of quantum dots to cool an otherwise isolated electron gas, potentially below the temperature of its host lattice. Such a device does not require specialised fabrication techniques and, in theory, can operate at arbitrarily low temperatures.

In this talk, we will present measurements of a Quantum Dot Refrigerator designed to cool an isolated 2DEG with an area of 6 square microns [2]. To interpret the results, a model has been developed which extends previous work to the regime of strong electrostatic coupling between the components of the device. Within the context of this model, the data show strong evidence for active cooling. We will discuss the practical limitations of such devices, methods for improving performance and evaluation, and potential applications.

[1] Edwards et al., PRB 52, p5714 (1995)
[2] Prance et al., PRL 102, 146602 (2009)
Host: Mark Eriksson
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