Quantum refrigerator at UCL
This photo shows a high-powered refrigerator, used for cooling samples to within a fraction of absolute zero. (When in operation, the refrigerator is entirely enclosed in a sealed and insulating casing.) As with a household fridge, the temperature is lower towards the bottom. The top shelf has a temperature of about 50 Kelvins (-223 Celsius), the next down is at around 4.4 kelvins (-269 Celsius), then 0.08K and 0.03K (-273 Celsius), just above absolute zero (0K).
The refrigerator is used to cool small objects, such as transistors, down to levels where thermal effects such as the vibration of the atoms in them are eliminated, allowing quantum effects to be observed.
The refrigerator, which is cooled by a mixture of Helium-3 and Helium-4, is located in UCL's department of Physics & Astronomy.
Photo credit: O. Usher (UCL MAPS)