| 词条 | Roton |
| 释义 |
In theoretical physics, a roton is an elementary excitation, or quasiparticle, in superfluid helium-4. The dispersion relation of elementary excitations in this superfluid shows a linear increase from the origin, but exhibits first a maximum and then a minimum in energy as the momentum increases. Excitations with momenta in the linear region are called phonons; those with momenta close to the minimum are called rotons. Excitations with momenta near the maximum are sometimes called maxons. The term "roton" is also used for the quantized eigenmode of a freely rotating molecule.{{citation needed|date=January 2016}} ModelsOriginally, the roton spectrum was phenomenologically introduced by Lev Landau. Currently there exist different models which try to explain the roton spectrum, with different degrees of success and fundamentality.[1][2] The requirement for any model of this kind is that it must explain not only the shape of the spectrum itself but also other related observables, such as the speed of sound and structure factor of superfluid helium-4. Microwave and Bragg spectroscopy has been conducted on helium to study the roton spectrum.[3] Bose–Einstein condensationBose–Einstein condensation of rotons has been also proposed and studied[4]. Its first detection has been reported in 2018[5]. See also
References1. ^{{Cite journal|url = |title = Fingerprinting Rotons in a Dipolar Condensate: Super-Poissonian Peak in the Atom-Number Fluctuations|last = |first = |date = 26 June 2013|journal = Phys. Rev. Lett. |volume=110 |page=265302|accessdate = |doi = 10.1103/PhysRevLett.110.265302|pmid = |arxiv = 1304.3605 |bibcode = 2013PhRvL.110z5302B }} 2. ^{{Cite journal|url = |title = Roton spectroscopy in a harmonically trapped dipolar Bose–Einstein condensate|last = |first = |date = Aug 15, 2012|journal = Phys. Rev. A |volume=86 |pages=021604 |accessdate = |doi = 10.1103/PhysRevA.86.021604|pmid = |arxiv = 1206.2770 |bibcode = 2012PhRvA..86b1604B }} 3. ^{{Cite journal|url = |title = Microwave Spectroscopy of Condensed Helium at the Roton Frequency|last = |first = |date = 4 Nov 2009|journal = Journal of Low Temperature Physics|accessdate = |doi = 10.1007/s10909-009-0025-6|pmid = |bibcode = 2010JLTP..158..244R }} 4. ^{{Cite journal|url = |title = The role of the condensate in the existence of phonons and rotons|last = |first = |date = December 1993|journal = Journal of Low Temperature Physics|accessdate = |doi = 10.1007/BF00692035|pmid = |bibcode = 1993JLTP...93..861G }} 5. ^{{cite journal|last1=Chomaz|first1=L.|title=Observation of roton mode population in a dipolar quantum gas|journal=Nature Physics|date=2018|doi=10.1038/s41567-018-0054-7|arxiv=1705.06914|bibcode=2018NatPh..14..442C}} Bibliography
2 : Quasiparticles|Bose–Einstein condensates |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。