Difference between revisions of "FourierMatrix"

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(Created page with "{{Function |name=FourierMatrix |desc=Generates the unitary matrix that implements the quantum Fourier transform |upd=November 30, 2012 |v=1.00}} <tt>'''FourierMatrix''...")
 
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{{Function
 
{{Function
 
|name=FourierMatrix
 
|name=FourierMatrix
|desc=Generates the [[unitary matrix]] that implements the [[quantum Fourier transform]]
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|cat=[[List of functions#Special_states,_vectors,_and_operators|Special states, vectors, and operators]]
|upd=November 30, 2012
+
|desc=Generates the unitary matrix that implements the quantum Fourier transform
|v=1.00}}
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|upd=November 30, 2012}}
<tt>'''FourierMatrix'''</tt> is a [[List of functions|function]] that returns the [[unitary matrix]] that implements the [[quantum Fourier transform]].
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<tt>'''FourierMatrix'''</tt> is a [[List of functions|function]] that returns the unitary matrix that implements the [http://en.wikipedia.org/wiki/Quantum_Fourier_transform quantum Fourier transform]. That is, it returns the $d \times d$ matrix
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: <math>\frac{1}{\sqrt{d}}\begin{bmatrix}1 & 1 & 1 & \cdots & 1 \\ 1 & \omega & \omega^2 & \cdots & \omega^{d-1} \\ 1 & \omega^2 & \omega^4 & \cdots & \omega^{2(d-1)} \\ \vdots & \vdots & \vdots & \ddots & \vdots \\ 1 & \omega^{d-1} & \omega^{2(d-1)} & \cdots & \omega^{(d-1)(d-1)} \end{bmatrix},</math>
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where $\omega := \exp(2\pi i/d)$ is a [http://en.wikipedia.org/wiki/Root_of_unity primitive d-th root of unity].
  
 
==Syntax==
 
==Syntax==
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==Examples==
 
==Examples==
 
===The qubit Fourier matrix===
 
===The qubit Fourier matrix===
The qubit Fourier matrix is simply the usual [[Hadamard gate]]:
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The qubit Fourier matrix is simply the usual Hadamard gate:
<pre>
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<syntaxhighlight>
 
>> FourierMatrix(2)
 
>> FourierMatrix(2)
  
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   0.7071            0.7071           
 
   0.7071            0.7071           
 
   0.7071            -0.7071 + 0.0000i
 
   0.7071            -0.7071 + 0.0000i
</pre>
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</syntaxhighlight>
  
 
===The three-qubit Fourier matrix===
 
===The three-qubit Fourier matrix===
 
The following line of code generates the three-qubit (i.e., <tt>DIM = 8</tt>) Fourier matrix, which can be seen [http://en.wikipedia.org/wiki/Quantum_Fourier_transform here]. The multiplication by <tt>sqrt(8)</tt> is just there to make the output easier to read.
 
The following line of code generates the three-qubit (i.e., <tt>DIM = 8</tt>) Fourier matrix, which can be seen [http://en.wikipedia.org/wiki/Quantum_Fourier_transform here]. The multiplication by <tt>sqrt(8)</tt> is just there to make the output easier to read.
<pre>
+
<syntaxhighlight>
 
>> FourierMatrix(8)*sqrt(8)
 
>> FourierMatrix(8)*sqrt(8)
  
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   1.0000            -0.0000 - 1.0000i  -1.0000 + 0.0000i  0.0000 + 1.0000i  1.0000 - 0.0000i  -0.0000 - 1.0000i  -1.0000 + 0.0000i  0.0000 + 1.0000i
 
   1.0000            -0.0000 - 1.0000i  -1.0000 + 0.0000i  0.0000 + 1.0000i  1.0000 - 0.0000i  -0.0000 - 1.0000i  -1.0000 + 0.0000i  0.0000 + 1.0000i
 
   1.0000            0.7071 - 0.7071i  -0.0000 - 1.0000i  -0.7071 - 0.7071i  -1.0000 + 0.0000i  -0.7071 + 0.7071i  0.0000 + 1.0000i  0.7071 + 0.7071i
 
   1.0000            0.7071 - 0.7071i  -0.0000 - 1.0000i  -0.7071 - 0.7071i  -1.0000 + 0.0000i  -0.7071 + 0.7071i  0.0000 + 1.0000i  0.7071 + 0.7071i
</pre>
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</syntaxhighlight>
 +
 
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{{SourceCode|name=FourierMatrix}}

Latest revision as of 13:33, 24 June 2015

FourierMatrix
Generates the unitary matrix that implements the quantum Fourier transform

Other toolboxes required none
Function category Special states, vectors, and operators

FourierMatrix is a function that returns the unitary matrix that implements the quantum Fourier transform. That is, it returns the $d \times d$ matrix \[\frac{1}{\sqrt{d}}\begin{bmatrix}1 & 1 & 1 & \cdots & 1 \\ 1 & \omega & \omega^2 & \cdots & \omega^{d-1} \\ 1 & \omega^2 & \omega^4 & \cdots & \omega^{2(d-1)} \\ \vdots & \vdots & \vdots & \ddots & \vdots \\ 1 & \omega^{d-1} & \omega^{2(d-1)} & \cdots & \omega^{(d-1)(d-1)} \end{bmatrix},\] where $\omega := \exp(2\pi i/d)$ is a primitive d-th root of unity.

Syntax

  • F = FourierMatrix(DIM)

Argument descriptions

  • DIM: The dimension of the system. In other words, F will be a DIM-by-DIM matrix.

Examples

The qubit Fourier matrix

The qubit Fourier matrix is simply the usual Hadamard gate:

>> FourierMatrix(2)

ans =

   0.7071             0.7071          
   0.7071            -0.7071 + 0.0000i

The three-qubit Fourier matrix

The following line of code generates the three-qubit (i.e., DIM = 8) Fourier matrix, which can be seen here. The multiplication by sqrt(8) is just there to make the output easier to read.

>> FourierMatrix(8)*sqrt(8)

ans =

   1.0000             1.0000             1.0000             1.0000             1.0000             1.0000             1.0000             1.0000          
   1.0000             0.7071 + 0.7071i   0.0000 + 1.0000i  -0.7071 + 0.7071i  -1.0000 + 0.0000i  -0.7071 - 0.7071i  -0.0000 - 1.0000i   0.7071 - 0.7071i
   1.0000             0.0000 + 1.0000i  -1.0000 + 0.0000i  -0.0000 - 1.0000i   1.0000 - 0.0000i   0.0000 + 1.0000i  -1.0000 + 0.0000i  -0.0000 - 1.0000i
   1.0000            -0.7071 + 0.7071i  -0.0000 - 1.0000i   0.7071 + 0.7071i  -1.0000 + 0.0000i   0.7071 - 0.7071i   0.0000 + 1.0000i  -0.7071 - 0.7071i
   1.0000            -1.0000 + 0.0000i   1.0000 - 0.0000i  -1.0000 + 0.0000i   1.0000 - 0.0000i  -1.0000 + 0.0000i   1.0000 - 0.0000i  -1.0000 + 0.0000i
   1.0000            -0.7071 - 0.7071i   0.0000 + 1.0000i   0.7071 - 0.7071i  -1.0000 + 0.0000i   0.7071 + 0.7071i  -0.0000 - 1.0000i  -0.7071 + 0.7071i
   1.0000            -0.0000 - 1.0000i  -1.0000 + 0.0000i   0.0000 + 1.0000i   1.0000 - 0.0000i  -0.0000 - 1.0000i  -1.0000 + 0.0000i   0.0000 + 1.0000i
   1.0000             0.7071 - 0.7071i  -0.0000 - 1.0000i  -0.7071 - 0.7071i  -1.0000 + 0.0000i  -0.7071 + 0.7071i   0.0000 + 1.0000i   0.7071 + 0.7071i

Source code

Click here to view this function's source code on github.