Του Γιώργου Λεκάκη
ΤΩΡΑ μιλάμε ανοικτά για την «Παράξενη ύλη»…
Έναν «εξωτικό» «πέμπτο τύπο ύλης»…
Η ουσία, που ονομάζεται συμπύκνωμα Bose-Einstein / Bose-Einstein condensate (BEC), θεωρήθηκε αρχικά από τους Albert Einstein και Satyendra Nath Bose, στις αρχές της δεκαετίας του 1920, ως η πέμπτη κατάσταση της ύλης, μετά από:
- τα στερεά,
- τα υγρά,
- τα αέρια και
- το πλάσμα.
Είναι στην ουσία ένα supercooled gas / υπερψυγμένο αέριο.
ΠΗΓΗ: David C. Aveline, Jason R. Williams, Ethan R. Elliott, Chelsea Dutenhoffer, James R. Kellogg, James M. Kohel, Norman E. Lay, Kamal Oudrhiri, Robert F. Shotwell, Nan Yu & Robert J. Thompson «Observation of Bose–Einstein condensates in an Earth-orbiting research lab», Nature, αρ. 582, σελ. 193-197, 11 June 2020, Nature, DOI: 10.1038/s41586-020-2346-1. ΑΡΧΕΙΟΝ ΠΟΛΙΤΙΣΜΟΥ, 12.6.2020.
Strange matter
An exotic fifth type of matter has been created in one of the coldest places in the universe – a device on board the International Space Station.
The substance, called a Bose-Einstein condensate (BEC), was initially theorised by Albert Einstein and Satyendra Nath Bose in the early 1920s as the fifth state of matter, following solids, liquids, gases and plasma. It is a supercooled gas that no longer behaves as individual atoms and particles, but rather an entity in a single quantum state.
The Cold Atom Laboratory, a suitcase-sized device launched to the ISS in 2018, chills atoms of rubidium and potassium in a vacuum chamber, using laser light to slow their movement.
Magnetic fields then contain the resulting cloud of atoms, which is cooled to nearly absolute zero at -273°C, producing a BEC.
The substance, called a Bose-Einstein condensate (BEC), was initially theorised by Albert Einstein and Satyendra Nath Bose in the early 1920s as the fifth state of matter, following solids, liquids, gases and plasma. It is a supercooled gas that no longer behaves as individual atoms and particles, but rather an entity in a single quantum state.
The Cold Atom Laboratory, a suitcase-sized device launched to the ISS in 2018, chills atoms of rubidium and potassium in a vacuum chamber, using laser light to slow their movement.
Magnetic fields then contain the resulting cloud of atoms, which is cooled to nearly absolute zero at -273°C, producing a BEC.
SOURCE: New Scientist.
Abstract
Quantum mechanics governs the microscopic world, where low mass and momentum reveal a natural wave–particle duality.
Magnifying quantum behaviour to macroscopic scales is a major strength of the technique of cooling and trapping atomic gases, in which low momentum is engineered through extremely low temperatures.
Advances in this field have achieved such precise control over atomic systems that gravity, often negligible when considering individual atoms, has emerged as a substantial obstacle. In particular, although weaker trapping fields would allow access to lower temperatures, gravity empties atom traps that are too weak. Additionally, inertial sensors based on cold atoms could reach better sensitivities if the free-fall time of the atoms after release from the trap could be made longer. Planetary orbit, specifically the condition of perpetual free-fall, offers to lift cold-atom studies beyond such terrestrial limitations.
Here we report production of rubidium Bose–Einstein condensates (BECs) in an Earth-orbiting research laboratory, the Cold Atom Lab.
We observe subnanokelvin BECs in weak trapping potentials with free-expansion times extending beyond one second, providing an initial demonstration of the advantages offered by a microgravity environment for cold-atom experiments and verifying the successful operation of this facility.
With routine BEC production, continuing operations will support long-term investigations of trap topologies unique to microgravity, atom-laser sources, few-body physics and pathfinding techniques for atom-wave interferometry.
Magnifying quantum behaviour to macroscopic scales is a major strength of the technique of cooling and trapping atomic gases, in which low momentum is engineered through extremely low temperatures.
Advances in this field have achieved such precise control over atomic systems that gravity, often negligible when considering individual atoms, has emerged as a substantial obstacle. In particular, although weaker trapping fields would allow access to lower temperatures, gravity empties atom traps that are too weak. Additionally, inertial sensors based on cold atoms could reach better sensitivities if the free-fall time of the atoms after release from the trap could be made longer. Planetary orbit, specifically the condition of perpetual free-fall, offers to lift cold-atom studies beyond such terrestrial limitations.
Here we report production of rubidium Bose–Einstein condensates (BECs) in an Earth-orbiting research laboratory, the Cold Atom Lab.
We observe subnanokelvin BECs in weak trapping potentials with free-expansion times extending beyond one second, providing an initial demonstration of the advantages offered by a microgravity environment for cold-atom experiments and verifying the successful operation of this facility.
With routine BEC production, continuing operations will support long-term investigations of trap topologies unique to microgravity, atom-laser sources, few-body physics and pathfinding techniques for atom-wave interferometry.
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