From bra-ket notation invented by Paul Dirac, from bracket.
Meanings
(qualifier:quantum mechanics) A column vector, in Hilbert space, especially as representing the state of a quantum mechanical system; the complex conjugate transpose of a bra (a row vector); a ket vector. Symbolised by |...〉.
A particular ket, say #124;A#92;rangle, might be represented by a particular column vector. Its corresponding bra, #92;langleA#124;, would then be represented by the row vector which is the transpose conjugate of that column vector.
fi ket (Translations) · it ket (Translations) · pl ket (Translations) · cmn 右矢 (Translations) · ja ケット (Translations) · de Ket (Translations) · bg кет (Translations)
Probably of Old Norse origin like kjǫt (“meat”), from Proto-Germanic *ketwą.
Compare Icelandic kjöt (“flesh”); akin to Swedish kött, Danish kød, and Norwegian kjøtt. The use of the term ket for "candy" or "sweets" probably derived from its use to describe sweet meats or as a deterrent to children.
Meanings
(Northern-England, countable, uncountable) Carrion; any filth.
(Northumbria, countable, uncountable) Sweetmeats.
(Wearside, countable, uncountable) A sweet, treat or candy.