Antiproton Decelerator<\/a> and binding them with positrons originating from a sodium-22 source.<\/p>\nThen, the resulting antihydrogen atoms are restricted to a magnetic trap, which prevents them from encountering matter and annihilating.<\/p>\n
Next, the team usually performs spectroscopic studies, that is, it measures the anti-atoms\u2019 response to electromagnetic radiation, laser light, or microwaves. These studies have enabled the team to conduct research such as measuring the 1S\u20132S electronic transition in antihydrogen with unprecedented precision.<\/p>\n
However, the precision of such spectroscopic measurements and of planned future measurements of the behaviour of antihydrogen in the Earth\u2019s gravitational field in ongoing experiments is limited by the kinetic energy or, equivalently, the temperature, of the antiatoms. This is where the laser cooling technique becomes invaluable.<\/p>\n
In this technique, laser photons are absorbed by the atoms, causing them to reach a higher-energy state. The anti-atoms then emit the photons and spontaneously decay back to their initial state.<\/p>\n
As the interaction depends on the atoms\u2019 velocity and as the photons impart momentum, repeating this absorption\u2013emission cycle many times leads to cooling of the atoms to a low temperature.<\/p>\n
In this study, the researchers found that they could laser-cool a sample of magnetically trapped antihydrogen atoms by repeatedly driving the anti-atoms from the atoms\u2019 lowest-energy state (the 1S state) to a higher-energy state (2P) using pulsed laser light with a frequency slightly below that of the transition between the two states.<\/p>\n
Once the trapped atoms had been illuminated for a few hours, the researchers detected a more than tenfold decrease in the atoms\u2019 median kinetic energy, with many of the anti-atoms attaining energies below a microeletronvolt, which is approximately 0.012 degrees above absolute zero in temperature equivalent.<\/p>\n
After successfully laser-cooling the anti-atoms, the researchers explored how the laser cooling affected a spectroscopic measurement of the 1S\u20132S transition, finding that the cooling led to a narrower spectral line for the transition \u2013 about four times narrower than that observed without laser cooling.<\/p>\n
\u201cOur demonstration of laser cooling of antihydrogen atoms and its application to 1S\u20132S spectroscopy represents the culmination of many years of antimatter research and developments at CERN\u2019s Antiproton Decelerator. This is by far the most difficult experiment we have ever done,\u201d added Hangst.<\/p>\n
\u201cHistorically, researchers have struggled to laser-cool normal hydrogen, so this has been a bit of a crazy dream for us for many years,\u201d says Makoto Fujiwara, the first proponent of the idea of using a pulsed laser to cool trapped antihydrogen in ALPHA. \u201cNow, we can dream of even crazier things with antimatter.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"
In a world first, the ALPHA collaboration at CERN has successfully cooled down antihydrogen atoms \u2013 the simplest form of atomic antimatter \u2013 using laser light.<\/p>\n","protected":false},"author":13,"featured_media":10455,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[766,24429],"tags":[821],"acf":[],"yoast_head":"\n
Cooling down antihydrogen atoms using laser light for the first time<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n \n \n\t \n\t \n\t \n