{"id":77031,"date":"2020-09-28T17:15:38","date_gmt":"2020-09-28T14:15:38","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/to-kill-a-quasiparticle-a-quantum-whodunit\/"},"modified":"2020-09-28T17:15:38","modified_gmt":"2020-09-28T14:15:38","slug":"to-kill-a-quasiparticle-a-quantum-whodunit","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/to-kill-a-quasiparticle-a-quantum-whodunit\/","title":{"rendered":"#To kill a quasiparticle: A quantum whodunit"},"content":{"rendered":"

“#To kill a quasiparticle: A quantum whodunit<\/strong>”<\/p>\n

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\n Over time, many-body dephasing kills the quasiparticle’s resemblance to a single particle. Credit: FLEET
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In large systems of interacting particles in quantum mechanics, an intriguing phenomenon often emerges: groups of particles begin to behave like single particles. Physicists refer to such groups of particles as ‘quasiparticles’.<\/p>\n


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Understanding the properties of quasiparticles may be key to comprehending, and eventually controlling, technologically important quantum effects like superconductivity and superfluidity.<\/p>\n

Unfortunately, quasiparticles are only useful while they live. It is thus particularly unfortunate that many quasiparticles die young, lasting far, far less than a second.<\/p>\n

The authors of a new Monash University-led study published today in Physical Review Letters<\/i> investigate the crucial question: how do quasiparticles die?<\/p>\n

Beyond the usual suspect\u2014quasiparticle decay into lower energy states\u2014the authors identify a new culprit: many-body dephasing.<\/p>\n

Many Body Dephasing<\/b><\/p>\n

Many-body dephasing is the disordering of the constituent particles in the quasiparticle that occurs naturally over time.<\/p>\n

As the disorder increases, the quasiparticle’s resemblance to a single particle fades. Eventually, the inescapable effect of many-body dephasing kills the quasiparticle.<\/p>\n

Far from a negligible effect, the authors demonstrate that many-body dephasing can even dominate over other forms of quasiparticle death.<\/p>\n

This is shown through investigations of a particularly ‘clean’ quasiparticle\u2014an impurity in an ultracold atomic gas\u2014where the authors find strong evidence of many-body dephasing in past experimental results.<\/p>\n

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\n Two spin states (red and green) of an impurity embedded in a Fermi sea (blue) are coupled together and undergo Rabi oscillations with an effective frequency ? and damping rate \u0393R. The damping rate is dominated by many-body dephasing. Credit: FLEET
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The authors focus on the case where the ultracold atomic gas is a Fermi sea. An impurity in a Fermi sea gives rise to a quasiparticle known as the repulsive Fermi polaron.<\/p>\n

The repulsive Fermi polaron is a highly complicated quasiparticle and has a history of eluding both experimental and theoretical studies.<\/p>\n

Through extensive simulations and new theory, the authors show that an established experimental protocol\u2014Rabi oscillations between impurity spin states\u2014exhibits the effects of many-body dephasing in the repulsive Fermi polaron.<\/p>\n

These previously unrecognized results provide strong evidence that many-body dephasing is fundamental to the nature of quasiparticles.<\/p>\n

The study was led by the School of Physics and Astronomy, Monash University, with co-authors from the Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche in Florence, Italy, and Ludwig-Maximilians-Universit\u00e4t in Munich, Germany.<\/p>\n\n

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Splitting quasiparticles with temperature: The fate of an impurity in a Bose-Einstein condensate\n <\/p><\/div>\n

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\n More information:<\/strong>
\n Haydn S. Adlong et al, Quasiparticle Lifetime of the Repulsive Fermi Polaron, Physical Review Letters<\/i> (2020). DOI: 10.1103\/PhysRevLett.125.133401<\/a><\/p><\/div>\n

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Citation<\/strong>:
\n To kill a quasiparticle: A quantum whodunit (2020, September 28)
\n retrieved 28 September 2020
\n from https:\/\/phys.org\/news<\/a>\/2020-09-quasiparticle-quantum-whodunit.html<\/p>\n

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\n part may be reproduced without the written permission. The content is provided for information purposes only.<\/p><\/div>\n<\/p><\/div>\n