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Motivation

Wet Fridges Reference- Matter and Methods at Low Temperatures, Frank Pobell Debaleena Nandi 06/12/14. Motivation. Integer and Fractional Quantum Hall Effect. A.D.K. Finck , Ph.D. Thesis. Motivation. Scanning Tunneling Microscope (STM) measurements. Motivation.

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Motivation

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  1. Wet FridgesReference- Matter and Methods at Low Temperatures, Frank PobellDebaleena Nandi06/12/14

  2. Motivation Integer and Fractional Quantum Hall Effect A.D.K. Finck, Ph.D. Thesis

  3. Motivation Scanning Tunneling Microscope (STM) measurements

  4. Motivation Cooling nanomechanical resonators to quantum ground states M. LaHaye, O. Buu, B. Camarota, K. Schwab, Science 304, 74 (2004)

  5. Lets make a decision on the cryogenic liquid He-3 and He-4 are our cryogenic liquids of choice, inert and lowest boiling and melting point

  6. Terrestrial availability of He-4 • He-4 • Alpha particle from radioactive decay of Uranium and Thorium • Half-life of =4.5× years; • Half-live of = 1.4× years; • Light gas, once released escapes from earth’s atmosphere • Trapped in few natural gas mines at ~1%

  7. Cooling to T 4.2K Liq He4 @ 4.2K Sample Outer Vacuum jacket

  8. Cooling to T 1.3K To He4 pump Liquid He4 Liq He4 @ 4.2K Inner Vacuum jacket Liq He4 @ 1.3K Sample Outer Vacuum jacket 40% of the liquid He4 has to be evaporated to cool to 1.3K

  9. Cooling to T 0.3K To He4 pump To He3 pump Liquid He4 Liq He4 @ 4.2K Inner vacuum jacket 1.3K Sample Liq He3 @ 0.3K Outer Vacuum jacket 20% of the liquid He3 has to be evaporated to cool to 0.3K

  10. Closed Cycle He3 Fridge T 0.3K To He4 pump Charcoal pump with heater Liquid He4 Liq He4 @ 4.2K Inner vacuum jacket 1.3K Sample Liq He3 @ 0.3K Outer Vacuum jacket 20% of the liquid He3 has to be evaporated to cool to 0.3K

  11. Cooling to T 10mK : Working principle Liq. He3 + Liq. He4 Liq He3 Liq He4 < Has to absorb latent heat of mixing from the surroundings He3/He4 mixture, more disordered state, Two phase separated liquids, more ordered state ,

  12. Phase diagram of He3-He4 mixtures 6.6% molar concentration of He3 in He4 even at T  0

  13. Operating principle of a dilution fridge Concept He3 Pump 1.3K 6.6% He3 in He3-He4 Liq. He3 He3-He4 Dilution Refrigerator

  14. Schematic of a He3-He4 dilution refrigerator To He3 pump 1.3K Still T=600mK > 90% He3 vapor <1% He3 <1% He3 in He3-He4 Still Heat Exchangers Heat Exchangers 100% Liq. He3 Mixing Chamber T=10mK 6.6% He3 in He3-He4 Sample

  15. He3-He4 dilution refrigerator

  16. Mixing chamber 100% Liq. He3 6.6% He3 in He3-He4 (Dilute phase) T=10mK

  17. Heat Exchanger

  18. Still > 90% He3 vapor <1% He3 <1% He3 in He3-He4

  19. IK Pot 1.3K

  20. Dumps

  21. Cooling to T< 1mK B B=0T PrNi5 rods Adiabatic demagnetization of nuclear magnetic moments

  22. Adiabatic nuclear demagnetization 100% Liq. He3 6.6% He3 in He3-He4 (Dilute phase) T=10mK Superconducting Switch PrNi5 rods (host the nuclear spins) B B=0T T=1mK T= 10mK Sample

  23. Conclusion • He3 Fridge – Latent Heat of Evaporation • He3-He4 Dilution Refrigerator- Heat of Solution Acknowledgements Jim Eisenstein, Aaron Finck & Johannes Pollanen

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