{"id":10044,"date":"2022-03-23T22:17:58","date_gmt":"2022-03-23T22:17:58","guid":{"rendered":"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/"},"modified":"2022-03-23T22:17:58","modified_gmt":"2022-03-23T22:17:58","slug":"what-is-the-difference-between-bra-and-ket","status":"publish","type":"post","link":"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/","title":{"rendered":"What is the difference between bra and ket?"},"content":{"rendered":"<p>Well, <strong>the<\/strong> &#8216;ket&#8217; notation represents vectors in <strong>the<\/strong> Hilbert space of states of the quantum system, while the &#8216;bra&#8217; notation represents co-vectors in the dual space.<\/p>\n<\/p>\n<p>Furthermore, what is the bra of a <strong>ket<\/strong>? Bra-ket notation is a standard notation for describing quantum states in the theory of quantum mechanics composed of angle brackets and vertical bars. It can also be used to denote abstract vectors and linear functionals in mathematics.<\/p>\n<p> In regards to, how do you turn a bra into a <strong>ket<\/strong>? Bra\u2013<strong>ket<\/strong> notation makes it particularly easy to compute the Hermitian conjugate (also called dagger, and denoted \u2020) of expressions. <strong>The<\/strong> formal rules are: The Hermitian conjugate of a <strong>bra<\/strong> is <strong>the<\/strong> corresponding ket, and vice versa. <strong>The<\/strong> Hermitian conjugate of a complex number is its complex conjugate.<\/p>\n<p>In this regard, is a bra the adjoint of a <strong>ket<\/strong>? <strong>Bra<\/strong>: A \u201cbra\u201d <\u00b7 | is \u201cdual\u201d to a vector which means that, with a ket, <strong>the<\/strong> bra gives a complex number, <\u00b7 | \u00b7> \u2208 C. The <strong>bra<\/strong> is an adjoint of the vector, <a |= (| a>)\u2020.<\/p>\n<p>Additionally, when a ket is multiplied by a <strong>bra<\/strong> we get? When you multiply a bra \u27e8a| by a ket |b\u27e9, with <strong>the<\/strong> <strong>bra<\/strong> on the left as in \u27e8a|b\u27e9, you&#8217;re computing an inner product. You&#8217;re asking for a single number that describes how much a and b align with each other. If a is perpendicular to b, then \u27e8a|b\u27e9 is zero.In standard notation you&#8217;d have to write out the components (infinitely many of them!) to demonstrate a row or a column. Bra-ket notation is nicer there. The &#8220;bras&#8221; \u27e8\u03c8| are dual vectors to the &#8220;kets&#8221; |\u03c8\u27e9. A more crazy and more useful interpretation is that bras are linear functions and kets are their arguments.<\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_75 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#How_do_you_write_bra_and_ket_in_Word\" >How do you write bra and ket in Word?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_are_the_physical_significances_of_bra_ket_vectors\" >What are the physical significances of bra ket vectors?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_is_a_bra_bracelet\" >What is a bra bracelet?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_is_a_state_ket\" >What is a state ket?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#How_do_operators_act_on_bras\" >How do operators act on bras?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_is_an_eigenstate\" >What is an eigenstate?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#Is_dot_product_and_inner_product_the_same\" >Is dot product and inner product the same?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#Can_you_multiply_two_kets\" >Can you multiply two kets?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_is_the_Hilbert_space_in_quantum_mechanics\" >What is the Hilbert space in quantum mechanics?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/pinkclubwear.com\/what-is-the-difference-between-bra-and-ket\/#What_is_a_dual_vector\" >What is a dual vector?<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"How_do_you_write_bra_and_ket_in_Word\"><\/span>How do you write bra and ket in Word?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>To do it just use the single bracket list as shown in the picture and select from it the relevant large < or > (far right of first row in pic). Then use shift forward slash (the button next to left-shift on most keyboards) to give the vertical line |. In combination you get correct bra-ket notation.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_are_the_physical_significances_of_bra_ket_vectors\"><\/span>What are the physical significances of bra ket vectors?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>Like all other notations used in mathematics and physics, the Bra &#038; Ket notation provides a means for a neat representation. The physical entities represented by Bras and Kets are vectors which are a bit different than vectors in a 3D space.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_is_a_bra_bracelet\"><\/span>What is a bra bracelet?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>A bra bracelet is exactly what it says, a bracelet made out of a bra. You make it using the bra strap, and it makes a cool elastic bracelet. Well, TikTok users think they&#8217;re cool at least. Whilst some choose to keep their bracelets plain, others are adding charms or sewing words and dates into it.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_is_a_state_ket\"><\/span>What is a state ket?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>to represent a quantum state. This is called a ket, or a ket vector. It is an abstract entity, and serves to describe the &#8220;state&#8221; of the quantum system. We say that a physical system is in quantum state , where represents some physical quantity, such as momentum, spin etc, when represented by the ket .<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"How_do_operators_act_on_bras\"><\/span>How do operators act on bras?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>As A acting to the left on bra vectors is really an operator V\u2217\u2192V\u2217 rather than an operator V\u2192V it usual in linear algebra to regard it as different operator A\u2217:V\u2217\u2192V\u2217 that is called the &#8220;conjugate,&#8221; or the &#8220;transpose.&#8221; The latter name is probably best as no complex conjugation is involved, and in the dual basis A\u2217 is &#8230;<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_is_an_eigenstate\"><\/span>What is an eigenstate?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>Definition of eigenstate : a state of a quantized dynamic system (such as an atom, molecule, or crystal) in which one of the variables defining the state (such as energy or angular momentum) has a determinate fixed value.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Is_dot_product_and_inner_product_the_same\"><\/span>Is dot product and inner product the same?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>An inner product is the more general term which can apply to a wide range of different vector spaces. The term scalar product can apply to more general symmetric bilinear form , for example for a pseudo-Euclidean space . The dot product is the name given to the inner product on a finite dimensional Euclidean space.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Can_you_multiply_two_kets\"><\/span>Can you multiply two kets?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>The author means the tensor product of the ket vectors. This is indeed a way of &#8220;multiplying&#8221; vectors together, although it&#8217;s subtle because the resulting product vector actually lies in a different vector space than the original ones.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_is_the_Hilbert_space_in_quantum_mechanics\"><\/span>What is the Hilbert space in quantum mechanics?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>\u51fb In quantum mechanics the state of a physical system is represented by a vector in a Hilbert space: a complex vector space with an inner product. \u25e6 The term \u201cHilbert space\u201d is often reserved for an infinite-dimensional inner product space having the property that it is complete or closed.<\/p>\n<\/p>\n<h2><span class=\"ez-toc-section\" id=\"What_is_a_dual_vector\"><\/span>What is a dual vector?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<\/p>\n<p>called dual vectors. The dual vector space is the set of all linear functions on V . The. elements of the space will (at least for now) be denoted with underlined Greek letters; the. value of the linear function \u03b1 on the vector v is a scalar; it will be denoted by \u03b1( v).<\/p>\n<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Well, the &#8216;ket&#8217; notation represents vectors in the Hilbert space of states of the quantum system, while the &#8216;bra&#8217; notation represents co-vectors in the dual space. Furthermore, what is the bra of a ket? Bra-ket notation is a standard notation for describing quantum states in the theory of quantum mechanics composed of angle brackets and &hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":""},"categories":[97],"tags":[],"modified_by":null,"_links":{"self":[{"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/posts\/10044"}],"collection":[{"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/comments?post=10044"}],"version-history":[{"count":0,"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/posts\/10044\/revisions"}],"wp:attachment":[{"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/media?parent=10044"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/categories?post=10044"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pinkclubwear.com\/wp-json\/wp\/v2\/tags?post=10044"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}