Mike Stay
May12-04, 01:41 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>I\'m trying to understand the concept of a POVM. I think it\'s\nsomething like classical probabilities applied to a complete set of\nprojection operators. I.e. first pick an orthonormal basis, and then\nfor each basis state, you pick an arbitrary classical probability\ndistribution over the set of possible results. That way, the mean\nvalue of any element of a POVM is the probability of getting that\nresult.\n\nIs that right?\n\nIs this a POVM for a qubit:\n\na=| 0.5 0 |,\n| 0 1 |\n\nb=| 0.1 0 |,\n| 0 0 |\n\nc=| 0.4 0 |?\n| 0 0 |\n\n\nIf so, the set {a^2, b^2, c^2} is not a POVM; how do you calculate the\nstandard deviation of elements of a POVM?\n\nThanks,\n--\nMike\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>I'm trying to understand the concept of a POVM. I think it's
something like classical probabilities applied to a complete set of
projection operators. I.e. first pick an orthonormal basis, and then
for each basis state, you pick an arbitrary classical probability
distribution over the set of possible results. That way, the mean
value of any element of a POVM is the probability of getting that
result.
Is that right?
Is this a POVM for a qubit:
a=| .5 |,
| 1 |
b=| .1 |,
| |
c=| .4 |?
| |
If so, the set {a^2, b^2, c^2} is not a POVM; how do you calculate the
standard deviation of elements of a POVM?
Thanks,
--
Mike
something like classical probabilities applied to a complete set of
projection operators. I.e. first pick an orthonormal basis, and then
for each basis state, you pick an arbitrary classical probability
distribution over the set of possible results. That way, the mean
value of any element of a POVM is the probability of getting that
result.
Is that right?
Is this a POVM for a qubit:
a=| .5 |,
| 1 |
b=| .1 |,
| |
c=| .4 |?
| |
If so, the set {a^2, b^2, c^2} is not a POVM; how do you calculate the
standard deviation of elements of a POVM?
Thanks,
--
Mike