Editing Quantum hydrodynamics (section)

{{Distinguish|Quantum hadrodynamics}}
In [[condensed matter physics]], '''quantum hydrodynamics''' ('''QHD''')<ref name="10.1007/978-3-319-05437-7--pp-103-152"> {{cite book |chapter= Quantum Hydrodynamics |pages= 103–152 |author=Shabbir A. Khan |author2=Michael Bonitz |title= Complex Plasmas |editor=Michael Bonitz |editor2=Jose Lopez |editor3=Kurt Becker |editor4=Hauke Thomsen |series= Springer Series on Atomic, Optical, and Plasma Physics |volume= 82 |publisher= Springer |doi= 10.1007/978-3-319-05437-7 |isbn= 978-3-319-05436-0 |issn= 1615-5653 |year= 2014 |bibcode= 2014cpsc.book.....B }} </ref> is most generally the study of hydrodynamic-like systems which demonstrate [[quantum mechanics|quantum mechanical]] behavior. They arise in [[Semiclassical physics|semiclassical mechanics]] in the study of metal and semiconductor devices, in which case being derived from the [[Boltzmann equation|Boltzmann transport equation]] combined with [[Wigner quasiprobability distribution]]. In [[quantum chemistry]] they arise as solutions to [[chemical kinetics|chemical kinetic]] systems, in which case they are derived from the [[Schrödinger equation]] by way of [[Madelung equations]].

An important system of study in quantum hydrodynamics is that of [[superfluidity]]. Some other topics of interest in quantum hydrodynamics are [[quantum turbulence]], [[quantized vortices]], [[second sound|second]] and [[third sound]], and [[quantum solvent]]s. The quantum hydrodynamic equation is an equation in [[Bohm interpretation|Bohmian mechanics]], which, it turns out, has a mathematical relationship to classical [[fluid dynamics]] (see [[Madelung equations]]). 

Some common experimental applications of these studies are in [[liquid helium]] ([[Helium-3|<sup>3</sup>He]] and [[Helium-4|<sup>4</sup>He]]), and of the interior of [[neutron star]]s and the [[quark–gluon plasma]]. Many famous scientists have worked in quantum hydrodynamics, including [[Richard Feynman]], [[Lev Landau]], and [[Pyotr Kapitsa]].