Editing Ytterbium (section)

==Applications==

===Source of gamma rays===
The <sup>169</sup>Yb [[isotope]] (with a [[half-life]] of 32 days), which is created along with the short-lived <sup>175</sup>Yb isotope (half-life 4.2 days) by [[neutron activation]] during the [[irradiation]] of ytterbium in [[nuclear reactor]]s, has been used as a [[radiation]] source in portable [[X-ray]] machines. Like X-rays, the [[gamma rays]] emitted by the source pass through soft tissues of the body, but are blocked by bones and other dense materials. Thus, small <sup>169</sup>Yb samples (which emit gamma rays) act like tiny X-ray machines useful for [[radiography]] of small objects. Experiments show that radiographs taken with a <sup>169</sup>Yb source are roughly equivalent to those taken with X-rays having energies between 250 and 350&nbsp;keV. <sup>169</sup>Yb is also used in [[nuclear medicine]].<ref>{{cite book|pages=168–169|url=https://books.google.com/books?id=wJqBSA1exqoC| title =Industrial radiology: theory and practice| author= Halmshaw, R. | publisher = Springer| date = 1995| isbn =978-0-412-62780-4}}</ref>

===High-stability atomic clocks===
A pair of experimental atomic clocks based on ytterbium atoms at the [[National Institute of Standards and Technology|National Institute of Standards and Technology (NIST)]] has set a record for stability. NIST physicists reported the ytterbium clocks' ticks are stable to within less than two parts in 1 [[quintillion]] (1 followed by 18 zeros), roughly 10 times better than the previous best published results for other atomic clocks. The clocks would be accurate within a second for a period comparable to the age of the universe. These clocks rely on about 10,000 ytterbium atoms [[Laser cooling|laser-cooled]] to 10 microkelvin (10 millionths of a degree above [[absolute zero]]) and trapped in an [[optical lattice]]—a series of pancake-shaped wells made of laser light. Another laser that "ticks" 518 trillion times per second (518 THz) provokes a transition between two energy levels in the atoms. The large number of atoms is key to the clocks' high stability.<ref>NIST (2013-08-22) [https://www.nist.gov/pml/div688/clock-082213.cfm Ytterbium Atomic Clocks Set Record for Stability].</ref>

Visible light waves oscillate faster than microwaves, hence optical clocks can be more precise than [[caesium]] [[atomic clocks]]. The [[Physikalisch-Technische Bundesanstalt]] is working on several such optical clocks. The model with one single ytterbium ion caught in an [[ion trap]] is highly accurate. The optical clock based on it is exact to 17 digits after the decimal point.<ref>Peik, Ekkehard (2012-03-01). [https://www.ptb.de/cms/en/presseaktuelles/journals-magazines/ptb-news/ptb-news-ausgaben/archivederptb-news/ptb-news-2012/new-pendulum-for-the-ytterbium-clock.html New "pendulum" for the ytterbium clock]. ptb.de.</ref>

===Doping of stainless steel===
Ytterbium can also be used as a [[dopant]] to help improve the grain refinement, strength, and other mechanical properties of [[stainless steel]]. Some ytterbium [[alloy]]s have rarely been used in [[dentistry]].<ref name="CRC" /><ref name="history" />

===Ytterbium as dopant of active media===
The Yb<sup>3+</sup> [[ion]] is used as a [[doping (semiconductors)|doping material]] in [[active laser medium|active laser media]], specifically in [[solid state laser]]s and [[double clad fiber]] lasers. Ytterbium lasers are highly efficient, have long lifetimes and can generate short pulses; ytterbium can also easily be incorporated into the material used to make the laser.<ref>{{cite thesis |last=Ostby |first=Eric |date=2009 |title=Photonic Whispering-Gallery Resonations in New Environments |url=https://thesis.library.caltech.edu/2284/4/03_Ch3_Ostby.pdf
|access-date=21 December 2012 |publisher=[[California Institute of Technology]]}}</ref> Ytterbium lasers commonly radiate in the 1.03–1.12&nbsp;[[μm]] band being [[optical pumping|optically pumped]] at wavelength 900&nbsp;nm–1&nbsp;μm, dependently on the host and application. The small [[quantum defect]] makes ytterbium a prospective dopant for efficient lasers and [[power scaling]].<ref>{{cite journal|doi=10.1070/QE2004v034n03ABEH002621|title=Broadband Radiation Source Based on an Ytterbium-Doped Fibre With Fibre-Length-Distributed Pumping|date=2004|author=Grukh, Dmitrii A.|journal=Quantum Electronics|volume=34|page=247|last2=Bogatyrev|first2=V. A.|last3=Sysolyatin|first3=A. A.|last4=Paramonov|first4=Vladimir M.|last5=Kurkov|first5=Andrei S.|last6=Dianov|first6=Evgenii M.|bibcode = 2004QuEle..34..247G|issue=3 |s2cid=250788004 }}</ref>

The kinetic of excitations in ytterbium-doped materials is simple and can be described within the concept of [[McCumber relation|effective cross-section]]s; for most ytterbium-doped laser materials (as for many other optically pumped gain media), the [[McCumber relation]] holds,<ref name="kouz05">{{cite journal|author=Kouznetsov, D.|author2=Bisson, J.-F.|author3=Takaichi, K.|author4=Ueda, K. |title=Single-mode solid-state laser with short wide unstable cavity|journal=[[Journal of the Optical Society of America B]]|volume=22| issue=8| pages=1605–1619|date=2005|doi=10.1364/JOSAB.22.001605|bibcode=2005JOSAB..22.1605K}}</ref><ref name="mc">
{{cite journal|author=McCumber, D.E. |title= Einstein Relations Connecting Broadband Emission and Absorption Spectra|journal= Physical Review B|volume= 136|issue=4A|pages=954–957|date=1964|doi=10.1103/PhysRev.136.A954|bibcode = 1964PhRv..136..954M }}</ref><ref name="B">{{cite book| author = Becker, P.C.| author2 = Olson, N.A.| author3 = Simpson, J.R. |title =Erbium-Doped Fiber Amplifiers: Fundamentals and Theory| publisher = Academic press| date = 1999}}</ref> although the application to the ytterbium-doped [[composite materials]] was under discussion.<ref name="McCumberA">{{cite journal |author=Kouznetsov, D. |title=Comment on Efficient diode-pumped Yb:Gd<sub>2</sub>SiO<sub>5</sub> laser|journal=Applied Physics Letters |volume=90|date=2007|doi=10.1063/1.2435309 |page=066101|bibcode = 2007ApPhL..90f6101K |issue=6 }}</ref><ref name="McCumberB">{{cite journal |author=Zhao, Guangjun |author2=Su, Liangbi |author3=Xu, Jun |author4=Zeng, Heping |title=Response to Comment on Efficient diode-pumped Yb:Gd<sub>2</sub>SiO<sub>5</sub> laser|journal=Applied Physics Letters |volume=90 |page=066103 |date=2007 |doi=10.1063/1.2435314|bibcode = 2007ApPhL..90f6103Z |issue=6 |doi-access=free }}</ref>

Usually, low concentrations of ytterbium are used. At high concentrations, the ytterbium-doped materials show [[photodarkening]]<ref name="photodarkening">{{cite journal |author=Koponen, Joona J. |author2=Söderlund, Mikko J. |author3=Hoffman, Hanna J. |author4=Tammela, Simo K. T. |name-list-style=amp |title= Measuring photodarkening from single-mode ytterbium doped silica fibers|journal=Optics Express|volume=14 |issue=24 |pages=11539–11544 |doi= 10.1364/OE.14.011539 |date= 2006 |pmid=19529573|bibcode = 2006OExpr..1411539K |s2cid=27830683 |doi-access=free }}</ref>
(glass fibers) or even a switch to broadband emission<ref name="avalanche">{{cite journal
|author=Bisson, J.-F.|author2=Kouznetsov, D.|author3=Ueda, K.|author4=Fredrich-Thornton, S. T.|author5=Petermann, K.|author6=Huber, G.|title=Switching of Emissivity and Photoconductivity in Highly Doped Yb<sup>3+</sup>:Y<sub>2</sub>O<sub>3</sub> and Lu<sub>2</sub>O<sub>3</sub> Ceramics |journal=Applied Physics Letters |volume=90 |page= 201901 |date=2007 |doi=10.1063/1.2739318|bibcode = 2007ApPhL..90t1901B|issue=20 }}</ref> (crystals and ceramics) instead of efficient laser action. This effect may be related with not only overheating, but also with conditions of [[charge compensation]] at high concentrations of ytterbium ions.<ref>{{cite journal|author=Sochinskii, N.V.|author2=Abellan, M.|author3=Rodriguez-Fernandez, J.|author4=Saucedo, E.|author5=Ruiz, C.M.|author6=Bermudez, V. |title=Effect of Yb concentration on the resistivity and lifetime of CdTe:Ge:Yb codoped crystals |date=2007 |journal=Applied Physics Letters |volume=91 |issue=20 |page=202112 |doi=10.1063/1.2815644|bibcode = 2007ApPhL..91t2112S |url=https://digital.csic.es/bitstream/10261/46803/1/ApplPhysLett_91_202112.pdf|hdl=10261/46803|hdl-access=free}}</ref>

Much progress has been made in the power scaling lasers and amplifiers produced with ytterbium (Yb) doped optical fibers. Power levels have increased from the 1&nbsp;kW regimes due to the advancements in components as well as the Yb-doped fibers. Fabrication of Low NA, Large Mode Area fibers enable achievement of near perfect beam qualities (M2<1.1) at power levels of 1.5&nbsp;kW to greater than 2&nbsp;kW at ~1064&nbsp;nm in a broadband configuration.<ref>{{cite journal|doi=10.1038/nphoton.2011.170|title=Doped fibres: Rare-earth fibres power up|journal=Nature Photonics|volume=5|issue=8|pages=466|year=2011|last1=Samson|first1=Bryce|last2=Carter|first2=Adrian|last3=Tankala|first3=Kanishka|bibcode=2011NaPho...5..466S}}</ref> Ytterbium-doped LMA fibers also have the advantages of a larger mode field diameter, which negates the impacts of nonlinear effects such as stimulated [[Brillouin scattering]] and stimulated [[Raman scattering]], which limit the achievement of higher power levels, and provide a distinct advantage over single mode ytterbium-doped fibers.

To achieve even higher power levels in ytterbium-based fiber systems, all factors of the fiber must be considered. These can be achieved only through optimization of all ytterbium fiber parameters, ranging from the core background losses to the geometrical properties, to reduce the splice losses within the cavity. Power scaling also requires optimization of matching passive fibers within the optical cavity.<ref>{{cite web |title=Fiber for Fiber Lasers: Matching Active and Passive Fibers Improves Fiber Laser Performance|url=http://www.laserfocusworld.com/articles/print/volume-48/issue-01/features/matching-active-and-passive-fibers-improves-fiber-laser-performance.html/|date=2012-01-01|publisher=[[Laser Focus World]]}}</ref> The optimization of the ytterbium-doped glass itself through host glass modification of various dopants also plays a large part in reducing the background loss of the glass, improvements in slope efficiency of the fiber, and improved photodarkening performance, all of which contribute to increased power levels in 1&nbsp;μm systems.

===Ion qubits for quantum computing===
The charged ion <sup>171</sup>Yb<sup>+</sup> is used by multiple academic groups and companies as the trapped-ion qubit for [[quantum computing]].<ref name="Olms1">{{cite journal |last1=Olmschenk |first1=S. |title=Manipulation and detection of a trapped Yb171<sup>+</sup> hyperfine qubit |journal=Physical Review A |date=Nov 2007 |volume=76 |issue=5 |pages=052314 |doi=10.1103/PhysRevA.76.052314 |bibcode=2007PhRvA..76e2314O |arxiv=0708.0657 |s2cid=49330988 }}</ref><ref>{{Cite web |title=Quantinuum {{!}} Hardware |url=https://www.quantinuum.com/hardware |access-date=2023-05-21 |website=www.quantinuum.com |language=en}}</ref><ref>{{Cite web |title=IonQ {{!}} Our Trapped Ion Technology |url=https://ionq.com/technology |access-date=2023-05-21 |website=IonQ |language=en}}</ref> [[Quantum entanglement|Entangling]] [[Quantum logic gate|gates]], such as the [[Mølmer–Sørensen gate]], have been achieved by addressing the ions with [[Mode-locking|mode-locked]] pulse lasers.<ref name="hay1">{{cite journal |last1=Hayes |first1=D. |title=Entanglement of Atomic Qubits Using an Optical Frequency Comb |journal=Physical Review Letters |date=Apr 2010 |volume=104 |issue=14 |pages=140501  |doi=10.1103/PhysRevLett.104.140501 |pmid=20481925 |bibcode=2010PhRvL.104n0501H |arxiv=1001.2127 |s2cid=14424109 }}</ref>

===Others===
Ytterbium metal increases its electrical resistivity when subjected to high stresses. This property is used in stress gauges to monitor ground deformations from earthquakes and explosions.<ref name="appl">{{cite book| page = 32| url = https://books.google.com/books?id=F0Bte_XhzoAC&pg=PA32| title = Extractive metallurgy of rare earths| author = Gupta, C.K.| author2 = Krishnamurthy, Nagaiyar| name-list-style = amp | publisher =CRC Press| date = 2004| isbn =978-0-415-33340-5}}</ref>

Currently, ytterbium is being investigated as a possible replacement for [[magnesium]] in high density pyrotechnic payloads for kinematic [[flare (countermeasure)|infrared decoy flares]]. As [[ytterbium(III) oxide]] has a significantly higher [[emissivity]] in the infrared range than [[magnesium oxide]], a higher radiant intensity is obtained with ytterbium-based payloads in comparison to those commonly based on [[magnesium/Teflon/Viton]] (MTV).<ref>{{Cite journal | last1 = Koch | first1 = E. C. | last2 = Hahma | first2 = A. | doi = 10.1002/zaac.201200036 | title = Metal-Fluorocarbon Pyrolants. XIV: High Density-High Performance Decoy Flare Compositions Based on Ytterbium/Polytetrafluoroethylene/Viton® | journal = Zeitschrift für Anorganische und Allgemeine Chemie | volume = 638 | issue = 5 | pages = 721 | year = 2012| doi-access = free }}</ref>