ShareRecent developments in extreme cooling
Researchers from NIST have demonstrated a solid-state refrigerator using quantum physics in micro- and nanostructures to cool a much larger object to extremely low temperatures. Moreover, a team of Munich’s Ludwig Maximilian University, has reached sub-absolute zero temperatures in a quantum gas made up of potassium atoms.
. Researchers from NIST have demonstrated a solid-state refrigerator using quantum physics in micro- and nanostructures to cool a much larger object to extremely low temperatures.
Solid-state refrigerators have applications such as cooling cryogenic sensors in highly sensitive instruments for semiconductor defect analysis and astronomical research.
The NIST refrigerator measures a few cm but has a cooling power equivalent to a window-mounted air conditioner cooling a large building. Its cooling elements comprise 48 sandwiches of normal metal, a 1-nm thick insulating layer and a superconducting metal. When voltage is applied, the hottest electrons tunnel from the normal metal through the insulator to the superconductor. The temperature in the normal metal drops dramatically while electronic and vibrational energy is drained from the object being cooled. The device chilled a plate of copper, 2.5 cm on a side and 3 mm thick from 290 to 256 mK in around 18 hours. NIST researchers expect that minor improvements could speed up the cooling process and lower temperatures to around 100 mK. They are now able to cool larger objects that can be easily attached and removed.
. But this is only one of several current attempts at reaching ultra-low temperatures: a team led by Professor Ulrich Schneider of Munich’s Ludwig Maximilian University, has reached sub-absolute zero temperatures in a quantum gas made up of potassium atoms.
This was achieved by using lasers and magnetic fields to adjust the magnetic fields so as to cause atoms to stick to their positions when their temperature is just above zero Kelvin. This shift, which prevents the atoms from collapsing inwards, marks the gas’s transition to a few billionths of a Kelvin below absolute zero.
Negative absolute temperatures had already been demonstrated in a magnetic system at the Massachusetts Institute of Technology in Cambridge, but this time the results presented motional degrees of atomic freedom and didn’t simply concern spin orientation. The applications of such a discovery are currently limited to research on the physics of condensed matter, for instance.
Solid-state refrigerators have applications such as cooling cryogenic sensors in highly sensitive instruments for semiconductor defect analysis and astronomical research.
The NIST refrigerator measures a few cm but has a cooling power equivalent to a window-mounted air conditioner cooling a large building. Its cooling elements comprise 48 sandwiches of normal metal, a 1-nm thick insulating layer and a superconducting metal. When voltage is applied, the hottest electrons tunnel from the normal metal through the insulator to the superconductor. The temperature in the normal metal drops dramatically while electronic and vibrational energy is drained from the object being cooled. The device chilled a plate of copper, 2.5 cm on a side and 3 mm thick from 290 to 256 mK in around 18 hours. NIST researchers expect that minor improvements could speed up the cooling process and lower temperatures to around 100 mK. They are now able to cool larger objects that can be easily attached and removed.
. But this is only one of several current attempts at reaching ultra-low temperatures: a team led by Professor Ulrich Schneider of Munich’s Ludwig Maximilian University, has reached sub-absolute zero temperatures in a quantum gas made up of potassium atoms.
This was achieved by using lasers and magnetic fields to adjust the magnetic fields so as to cause atoms to stick to their positions when their temperature is just above zero Kelvin. This shift, which prevents the atoms from collapsing inwards, marks the gas’s transition to a few billionths of a Kelvin below absolute zero.
Negative absolute temperatures had already been demonstrated in a magnetic system at the Massachusetts Institute of Technology in Cambridge, but this time the results presented motional degrees of atomic freedom and didn’t simply concern spin orientation. The applications of such a discovery are currently limited to research on the physics of condensed matter, for instance.