Cryogenics is the study of material sciences at extremely low temperatures. Cryogenic temperatures are generally regarded to be below -180° Celsius.
Cryogenics has many use cases in manufacturing and is often used in stress tests to evaluate the design of materials and products used in winter environments. Cryogenics often involves the use of liquid nitrogen or liquid helium, both of which are stored compressed at very low temperature. Once introduced to normal atmospheric temperatures, these two compounds boil, evaporating and rapidly cooling whatever vessel they might be used in.
Cryogenics are of particular interest when applied to electricity and silicon-based semiconductor processors, because super cooling can be used to bring about superconductivity. In a superconductor, electrons flow through the material with no loss to resistance, enabling greater performance by way of higher possible operating frequencies.
Cryogenics is often confused with cryonics, but they are not the same thing. Cryonics is the practice of deep-freezing recently deceased organisms for later revival.
Cryogenics in the data center
Cryocoolers are a type of cryogenic cooler used in data centers. They are based on the principles of Stirling heat engines, a cooling concept that has been used for decades in many industries. The problem with using cryocoolers in the data center, however, is that the heat engines have to be large enough to be effective -- and this can be difficult in a data center where physical space is at a premium.
In the past, cryocoolers were used for in-cabinet or in-row cooling. The challenge was always to route enough hot air to the cryocooler to run it effectively, and then use the cold junction generated to create a closed-loop cooling system. This required enough fans and ducting to ensure air-flows worked adequately, once again presenting the challenge of having enough physical space to make the use of cryocoolers be cost-effective.
Cryogenics and quantum computing
In today's data center, the term cryogenics is often associated with quantum computing. Quantum computers depend on super cooling for normal operation, which means that all of the components have to work at cryogenic temperatures. A major challenge of building quantum computing systems is how to permit superconducting qubits to reside in a cryogenic enclosure, while allowing the control and readout circuits to operate at room temperature.