LEARNING OUTCOMES

Acquisition of advanced experimental knowledges and methodologies of thermodynamics applied to low temperatures and to the detection of radiation, thermal sensors and associated electronics.

AIMS AND LEARNING OUTCOMES

The objective of the course is the acquisition of knowledge and experimental methodologies of vacuum and low temperatures for the experimental study of complex thermodynamic systems such as superfluid and superconducting ones. The course concludes with the experimental study of one or two of the following low temperature devices that are of interest for technological scientific applications: superconducting junctions (SIS), quantum interference devices (SQUID), quantum dots (QDot) and single electron transistors (SET), bolometers and superconducting calorimeters (TES). The technologies of vacuum and low temperature production and, even if still sporadically, those of low temperature devices, are now used by many industries (Thales Alenia Space (Mi), Kaiser Italia (Li), Simic (Cn) , Rial Vacuum (Pr), Pasquali MicrowaveSystem (Fi), ASG (Ge), Columbus (Ge), Agilent Technologies (To), ...), therefore these topics have professionalizing value. Recently, the skills in these fields are appreciated in the developments for quantum computation that are underway in several universities and public and private research centers.

PREREQUISITES

TEACHING METHODS

Lectures in the classroom and 6 afternoon experiences of about 4 hours in the didactic laboratory of low temperatures. The texts indicated and the lecture notes, which will be published on the Aulaweb website, represent the main teaching aids. The laboratory work are introduced in class while the details of the excursion are discussed before the experience begins.

SYLLABUS/CONTENT

Vacuum:  fluid sealed and dry primary pumps, turbomolecular, fluid, getter and ionic pumps, vacuum measurement with mechanical, thermal, ionic hot and cold cathode transducers. Cryogenics: Stirling and Gifford Mac Mahon cycles, pulsed tubes, gas liquefaction and Joule-Thomson expansion, nitrogen and helium liquefactors, magnetic refrigeration, dilution coolers. Temperature measurements: absolute and standard temperature scale up to mK, primary and secondary thermometers. Physics of some low temperature systems: electrical and thermal conduction, superfluidity and lambda transition, He-I and He-II and London model, thermomechanical effects, superconductivity and its experimental evidence, classification in type I and II superconductors, elements of microscopic BCS theory and forbidden gap, superconductor thermodynamics and elements of Ginzburg Landau theory. Physics of some low-temperature devices, one or two selected from: superconducting junctions (SIS), quantum interference device (SQUID), quantum dots (QDot) and single electron transistor (SET), bolometers and superconducting calorimeters (TES). Laboartory works: 1- cooling with LHe and measurement of the thermal input of a cryostat; 2- absolute Kelvin thermometry with calibration of a secondary thermometer; 3 - HeI-He-II lambda phase transition and superfluidity; 4-transition from normal conduction to superconducting state; 5- IV characteristic of a Superconductor-Insulator-Superconductor tunnel junction and prohibited gap; 6. quantum interference in the SQUID.

RECOMMENDED READING/BIBLIOGRAPHY

Zemansky: “Calore e Termodinamica” ; G.K.White: “Experimental Techniques in low temperature physics”; R. Richardson, E. Smith: “Experimental Techniques in Condensed Matter Physics and Low temperature”; O.V. Lounasma: “Experimental Principles and Methods Below 1K”.