Old exam question

Old exam question

par Jérémy Valentin Barghorn,
Nombre de réponses : 1

Hello,

I was doing an old exam question and here is the exercice : 


I was doing question d) and previously found this expression for p_t

From this I have no idea how I should proceed to draw this on the Bloch sphere as stated in question d) ? Is there an easy way to do this ?

Thanks in advance for the help !

En réponse à Jérémy Valentin Barghorn

Re: Old exam question

par Nicolas Macris,
You can write the density matrix of a single qubit as follows:

rho = (1/2)( Id + \vec(a) . \vec(sigma))

Now \vec(a) is a time-dependent three dimensional vector (with real components) in the Bloch ball. You have to identify the three
components of \vec(a).

Hope this helps.
N.M