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NEW HELIUM-FREE REFRIGERATOR
R. Blaauwgeers, P. Hakonen, L. Lechner, P. Vorselman, and M. Wiesner
Most of our effort in developing new high frequency techniques has gone to the construction of a new refrigerator setup. The core component of this apparatus is a pulse tube cooled 3He/4He dilution refrigerator. The cryostat is a pre-series version built by BlueFors Cryogenics, a Low Temperature Laboratory spin-off company. It has successfully completed its test runs in December 2007. The system does not rely on liquid helium pre-cooling like conventional cryostats. This construction leaves more room for samples and electronics, and allows to carry out measurements in vacuum. Overall, the comparably short length and clean design make it ideal for the challenging integration of noise measurement circuitry.
Meri Helle, Tommy Holmqvist, Antti Kemppinen, Matthias Meschke, Juha Muhonen, Mikko Möttönen, Jukka Pekola, Joonas Peltonen, Olli-Pentti Saira, Alexander Savin, Andrey Timofeev, and Juha Vartiainen
Visitors: Dmitri Averin, Francesco Giazotto, Wiebke Guichard, Frank Hekking, and Stefano Tirelli
The main highlights of the research in PICO group in 2007 were electronic refrigeration and thermometry, and charge pumping in superconducting and normal metal structures. We investigated the interplay of Coulomb effects and refrigeration; a heat transistor based on single-electron tunneling was developed. The highlight of the year was the concept and demonstration of a hybrid single-electron turnstile. One more achievement was the observation of the third moment of shot noise detected by a Josephson junction threshold detector.
Meri Helle, Matthias Meschke, Juha Muhonen, Jukka Pekola, Olli-Pentti Saira, Alexander Savin, and Andrey Timofeev
Collaborators: Francesco Giazotto (SNS), Wiebke Guichard (CNRS), Frank Hekking (CNRS), Nikolai Kopnin (LTL), and Stefano Tirelli (SNS)
The unifying topic in 2007 in the investigation of thermal effects in nanostructures was the influence of Coulomb interaction in electronic refrigeration. A gate controlled
Annual Report 2007