decomposition of general unitary












1












$begingroup$


Does anybody know how to prove the following:
Given a unitary matrix $U$, prove that:
$$U = V sigma_x V^dagger W sigma_x W^dagger$$



For the proper $V$ and $W$.
Any help is greatly appreciated.










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is $sigma_x$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:28






  • 1




    $begingroup$
    @RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:33








  • 1




    $begingroup$
    If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:34










  • $begingroup$
    @Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:43






  • 1




    $begingroup$
    @RobertLewis I think $U$ is of size $2$
    $endgroup$
    – Omnomnomnom
    Jan 25 at 0:53
















1












$begingroup$


Does anybody know how to prove the following:
Given a unitary matrix $U$, prove that:
$$U = V sigma_x V^dagger W sigma_x W^dagger$$



For the proper $V$ and $W$.
Any help is greatly appreciated.










share|cite|improve this question











$endgroup$












  • $begingroup$
    What is $sigma_x$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:28






  • 1




    $begingroup$
    @RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:33








  • 1




    $begingroup$
    If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:34










  • $begingroup$
    @Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:43






  • 1




    $begingroup$
    @RobertLewis I think $U$ is of size $2$
    $endgroup$
    – Omnomnomnom
    Jan 25 at 0:53














1












1








1





$begingroup$


Does anybody know how to prove the following:
Given a unitary matrix $U$, prove that:
$$U = V sigma_x V^dagger W sigma_x W^dagger$$



For the proper $V$ and $W$.
Any help is greatly appreciated.










share|cite|improve this question











$endgroup$




Does anybody know how to prove the following:
Given a unitary matrix $U$, prove that:
$$U = V sigma_x V^dagger W sigma_x W^dagger$$



For the proper $V$ and $W$.
Any help is greatly appreciated.







matrices matrix-decomposition






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 24 at 22:27









Robert Lewis

48.1k23167




48.1k23167










asked Jan 24 at 22:20







user638016



















  • $begingroup$
    What is $sigma_x$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:28






  • 1




    $begingroup$
    @RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:33








  • 1




    $begingroup$
    If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:34










  • $begingroup$
    @Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:43






  • 1




    $begingroup$
    @RobertLewis I think $U$ is of size $2$
    $endgroup$
    – Omnomnomnom
    Jan 25 at 0:53


















  • $begingroup$
    What is $sigma_x$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:28






  • 1




    $begingroup$
    @RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:33








  • 1




    $begingroup$
    If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
    $endgroup$
    – Omnomnomnom
    Jan 24 at 22:34










  • $begingroup$
    @Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
    $endgroup$
    – Robert Lewis
    Jan 24 at 22:43






  • 1




    $begingroup$
    @RobertLewis I think $U$ is of size $2$
    $endgroup$
    – Omnomnomnom
    Jan 25 at 0:53
















$begingroup$
What is $sigma_x$?
$endgroup$
– Robert Lewis
Jan 24 at 22:28




$begingroup$
What is $sigma_x$?
$endgroup$
– Robert Lewis
Jan 24 at 22:28




1




1




$begingroup$
@RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
$endgroup$
– Omnomnomnom
Jan 24 at 22:33






$begingroup$
@RobertLewis Presumably they're referring to the Pauli matrix $$ sigma_x = pmatrix{0&1\1&0} $$
$endgroup$
– Omnomnomnom
Jan 24 at 22:33






1




1




$begingroup$
If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
$endgroup$
– Omnomnomnom
Jan 24 at 22:34




$begingroup$
If I have interpreted your question correctly, I think this is possible if and only if $U$ is unitary with determinant $1$.
$endgroup$
– Omnomnomnom
Jan 24 at 22:34












$begingroup$
@Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
$endgroup$
– Robert Lewis
Jan 24 at 22:43




$begingroup$
@Omnomnomnom; so either $U$ is of size $2$ or $V, W$ are $n times 2$?
$endgroup$
– Robert Lewis
Jan 24 at 22:43




1




1




$begingroup$
@RobertLewis I think $U$ is of size $2$
$endgroup$
– Omnomnomnom
Jan 25 at 0:53




$begingroup$
@RobertLewis I think $U$ is of size $2$
$endgroup$
– Omnomnomnom
Jan 25 at 0:53










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