Dyade Dirac Notation: Why Last Equation?

In summary, the conversation discusses the use of Dirac notation to represent dyadic products. The equations shown involve the dot product of vectors and the use of brackets to represent kets and bras. The confusion arises when trying to differentiate between kets and bras in tensor analysis. The conversation concludes with a question about why the arrow notation is used for vectors when kets are already represented as vectors.
  • #1
LagrangeEuler
717
20
[tex]\{\vec{A},\vec{B}\}\cdot \vec{C}=\vec{A}(\vec{B}\cdot \vec{C})[/tex]
[tex]\vec{C} \cdot \{\vec{A},\vec{B}\}=(\vec{C}\cdot \vec{A}) \vec{B}[/tex]

I want to write dyade in Dirac notation.

[tex](|\vec{A}\rangle\langle\vec{B}|)|\vec{C}\rangle= |\vec{A}\rangle\langle\vec{B}|\vec{C}\rangle[/tex]
[tex]\langle\vec{C}|(|\vec{A}\rangle\langle\vec{B}|)=< \vec{C} |\vec{A}\rangle|\vec{B}\rangle[/tex]

Why not

[tex]\langle \vec{C} |\vec{A}\rangle\langle \vec{B}|[/tex]

in last equation?
 
Physics news on Phys.org
  • #2
It should be, it should have the same 'bra-keting' as the C in the LHS.
 
  • #3
I'm confused. In QM [tex]|\psi \rangle[/tex] and [tex]\langle \psi |[/tex] are vectors from some vector space and his dual respectively. But in some tensor analyses I don't see difference between [tex]|\vec{A}\rangle[/tex] and [tex]\langle \vec{A}|[/tex].
In this case precisely. I have some number [tex]\langle|\rangle[/tex] which multiply vector.
 
  • #4
LagrangeEuler said:
I'm confused. In QM [tex]|\psi \rangle[/tex] and [tex]\langle \psi |[/tex] are vectors from some vector space and his dual respectively. But in some tensor analyses I don't see difference between [tex]|\vec{A}\rangle[/tex] and [tex]\langle \vec{A}|[/tex].
In this case precisely. I have some number [tex]\langle|\rangle[/tex] which multiply vector.
I don't follow what you're saying here. Yes, ##\langle C|A\rangle## is a number. Why is that a problem?

There's no need to use the arrow notation for vectors here (unless what you have in mind is that ##\vec A## is a vector in some other vector space ##\mathbb R^3##), since kets are always vectors.
 

What is Dyade Dirac Notation?

Dyade Dirac Notation, also known as bra-ket notation, is a mathematical notation used to represent quantum states in quantum mechanics. It was developed by physicist Paul Dirac as a more concise and elegant way to express complex equations and calculations in quantum mechanics.

Why is the last equation in Dyade Dirac Notation?

The last equation in Dyade Dirac Notation, also known as the "bra-ket" notation, is used to represent an inner product between two quantum states. This notation is commonly used in quantum mechanics because it simplifies complex equations and allows for a more intuitive and visual understanding of quantum states.

How is Dyade Dirac Notation used in quantum mechanics?

Dyade Dirac Notation is used in quantum mechanics to represent the state of a quantum system, as well as to perform mathematical operations such as addition, subtraction, and multiplication of quantum states. It is also used to represent quantum observables and calculate probabilities of measurement outcomes.

What are the benefits of using Dyade Dirac Notation?

One of the main benefits of using Dyade Dirac Notation is its ability to simplify and condense complex equations and calculations in quantum mechanics. It also allows for a more intuitive and visual understanding of quantum states and operations. Additionally, it is a universal notation and can be used in various branches of physics.

Are there any drawbacks to using Dyade Dirac Notation?

While Dyade Dirac Notation has many benefits, it can also be confusing for those who are not familiar with it. It also has limitations in expressing certain types of calculations and can become cumbersome when dealing with multiple quantum states. Additionally, it is not commonly used in other fields of science, making it less accessible for interdisciplinary research.

Similar threads

Replies
2
Views
302
Replies
2
Views
263
  • Quantum Physics
Replies
1
Views
549
  • Quantum Physics
Replies
5
Views
496
Replies
167
Views
7K
  • Quantum Physics
Replies
4
Views
1K
Replies
1
Views
1K
  • Quantum Physics
Replies
4
Views
1K
  • Quantum Physics
Replies
6
Views
802
  • Calculus and Beyond Homework Help
Replies
5
Views
928
Back
Top