gstate_stabilizer.m

来自「该算法是用于量子运算的matlab程序」· M 代码 · 共 55 行

%gstate_stabilizer    Gets the generators for the stabilizer of a graph state.
%   gstate_stabilizer(Gamma) gives the generator for the stabilizer 
%   for a graph state corresponding to a connectivity matrix Gamma.

% Copyright (C) 2005  Geza Toth    E.mail: [e-mail]
%
% This program is free software; you can redistribute it and/or
% modify it under the terms of the GNU General Public License
% as published by the Free Software Foundation; see gpl.txt
% of this subroutine package.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
% 
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 51 Franklin Street, Fifth Floor, 
% Boston, MA  02110-1301, USA.

function stab=gstate_stabilizer(Gamma)

x=[0 1;1 0];
z=[1 0;0 -1];
y=i*x*z;

[sy,sx]=size(Gamma);
N=sy;

stab=cell(N,1);
for n=1:N
   op=1;
   for m=1:n-1
      if Gamma(n,m)>0,
         op2=z;
      else
         op2=eye(2);
      end %if
      op=kron(op,op2);    
   end %for
   op=kron(op,x);
   for m=n+1:N
      if Gamma(n,m)>0,
         op2=z;
      else
         op2=eye(2);
      end %if
      op=kron(op,op2);    
   end %for
   stab{n}=op;
end %for