Simple Dirac Notation Problem: Dot Product of Two Vectors

In summary, The conversation discusses the use of vectors and the dot product using Dirac's notation. It is mentioned that in this notation, a state vector corresponding to a wavefunction is written as |a>, and the dot product is represented by <c|a>. The use of the complex conjugate is also mentioned, with the equation <c|a> = [<a|* + <b|*] |a> = <a*|a> + <b*|a>, with * representing the complex conjugate of the vector. It is also noted that in this notation, |c> is not necessarily normalized.
  • #1
Jalo
120
0

Homework Statement



Imagine you have two vectors |a> and |b> such that:
|c> = |a> + |b>

Now imagine you want the dot product:

<c|a>

Is that the same as:

<c|a> = [ <a|*+<b|* ] |a> = <a*|a> + <b*|a>

where * represents the complex conjugate of the vector?


Homework Equations





The Attempt at a Solution

~

Thanks in advance for any answer.

Daniel
 
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  • #2
You'd not normally put the star outside the bra like that.
if a is a state then |a> is the state vector corresponding to wavefunction Ya ... we may sometimes write |Ya> when you are starting out.

##<\psi_a|\psi>= \int \psi_a^\star \psi##

(I'm hoping someone else can do a better job of this explanation. :/ )
BTW: you know your vector |c> is not normalized right?
 
  • #3
Simon Bridge said:
You'd not normally put the star outside the bra like that.
if a is a state then |a> is the state vector corresponding to wavefunction Ya ... we may sometimes write |Ya> when you are starting out.

##<\psi_a|\psi>= \int \psi_a^\star \psi##

(I'm hoping someone else can do a better job of this explanation. :/ )
BTW: you know your vector |c> is not normalized right?

Yes, I'm aware that |c> is not normalized, but in this case it doesn't matter. I'm just learning the math behind Dirac's notation. I am not yet working with state vectors or anything of that kind.
Thanks for your answer!
 

1. What is Dirac notation?

Dirac notation, also known as bra-ket notation, is a mathematical notation used to describe the state of a quantum system. It was developed by physicist Paul Dirac and is commonly used in quantum mechanics.

2. How do you write a simple Dirac notation problem?

A simple Dirac notation problem involves using the bra-ket notation to represent a quantum state and performing mathematical operations on it. For example, you can write a simple problem such as <A|B>, which represents the inner product of the bra vector <A| and the ket vector |B>.

3. What is the significance of the bra and ket in Dirac notation?

The bra vector <A| represents the conjugate transpose of the ket vector |A>. This notation allows for convenient representation of quantum states and operators, and simplifies the mathematical calculations involved in quantum mechanics.

4. Can you use Dirac notation for classical systems?

No, Dirac notation is specifically designed for quantum systems. However, it can be extended to classical systems by treating them as special cases of quantum systems with infinite energy levels.

5. What are some common operations performed using Dirac notation?

Some common operations performed using Dirac notation include calculating inner and outer products, calculating expectation values, and solving eigenvalue problems. It is also used to represent operators such as Hamiltonians and observables.

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