ChoiMatrix

ChoiMatrix
Computes the Choi matrix of a superoperator
Other toolboxes required	ApplyMap iden MaxEntangled opt_args PermuteSystems

ChoiMatrix is a function that computes the Choi matrix of a superoperator.

Syntax

• C = ChoiMatrix(PHI)
• C = ChoiMatrix(PHI,SYS)

Argument descriptions

• PHI: A superoperator. Should be provided as either a Choi matrix, or as a cell with either 1 or 2 columns (see the tutorial page for more details about specifying superoperators within QETLAB).
• SYS (optional, default 2): The subsystem that PHI is applied to when constructing the Choi matrix.

Examples

The transpose map

The Choi matrix of the transpose map is the swap operator, which is verified in the 2-dimensional case by the following code:

>> T = {[1 0;0 0],[1 0;0 0]';[0 1;0 0],[0 1;0 0]';[0 0;1 0],[0 0;1 0]';[0 0;0 1],[0 0;0 1]'};
>> ChoiMatrix(T)

ans =

     1     0     0     0
     0     0     1     0
     0     1     0     0
     0     0     0     1