<div dir="ltr"><div class="gmail_quote"><div dir="ltr"><br></div><div style="text-align:center" dir="ltr"><b style="font-family:"Times New Roman",serif;font-size:12.8px"><b><u><span lang="ES" style="font-family:Arial,sans-serif"><span class="m_3759536966608586645m_-1281441597324230559m_-6527446560211141204gmail-m_1631295547278110990gmail-il">COLOQUIOS</span> y SEMINARIOS del IFLP</span></u></b></b></div><div class="gmail_quote" dir="ltr"><div class="gmail_quote" dir="ltr"><div dir="ltr"><p style="text-align:center"><b><u><span style="font-family:Arial,sans-serif">MARTES 4 de DICIEMBRE – 11hs</span></u></b></p><b><u><span style="font-family:Arial,sans-serif"><p class="MsoNormal" style="margin:0cm 0cm 0.0001pt;font-size:12.8px;text-align:center;font-family:"Times New Roman",serif"><br></p></span></u></b><div style="text-align:justify"><b style="font-size:12.8px;font-family:"Times New Roman",serif"><u><span style="font-family:Arial,sans-serif">TÍTULO</span></u></b><b style="font-size:12.8px;font-family:"Times New Roman",serif"><span lang="PT-BR" style="font-family:Arial,sans-serif">:</span></b><b> </b><font face="tahoma, sans-serif"><b>Attainability of the quantum information bound in pure state models </b></font></div><div style="font-size:12.8px"><br></div><div><b style="font-size:12.8px;font-family:"Times New Roman",serif"><u><span style="font-family:Arial,sans-serif">EXPOSITOR:</span></u></b><span style="font-size:12.8px"> </span><b><font face="arial, helvetica, sans-serif" style="font-size:12.8px"> </font><font face="arial,helvetica,sans-serif" style="font-size:12.8px">Dr. Fabricio Toscano</font></b></div><font face="trebuchet ms, sans-serif"><span style="color:rgb(0,0,0)">Prof. Associado do Instituto de Física da </span></font><span style="color:rgb(0,0,0)"><font face="trebuchet ms, sans-serif">Universidade Federal do Rio de Janeiro (UFRJ) - Brasil </font></span><div><br></div><div><span style="font-size:12.8px;font-variant-east-asian:normal;line-height:normal"><font face="arial, helvetica, sans-serif"><b style="text-align:justify"><u>RESUMEN</u></b><b style="text-align:justify"><span lang="PT-BR">: </span></b></font></span><font face="arial, helvetica, sans-serif">The attainability of the quantum Cramér-Rao bound [QCR], the ultimate limit in the precision of the estimation of a physical parameter, requires the saturation of the quantum information bound [QIB]. This occurs when the Fisher information associated to a given measurement on the quantum state of a system which encodes the information about the parameter coincides with the quantum Fisher information associated to that quantum state.</font></div><div><div><font face="arial, helvetica, sans-serif">Braunstein and Caves [PRL 72, 3439 (1994)] have shown that the QIB can always be achieved via a projective measurement in the eigenvectors basis of an observable called symmetric logarithmic derivative. However, such projective measurement depends, in general, on the value of the parameter to be estimated. Requiring, therefore, the previous knowledge of the quantity one is trying to estimate. For this reason, it is important to investigate under which situation it is possible to saturate the QCR without previous information about the parameter to be estimated. </font></div><div><font face="arial, helvetica, sans-serif">Here, we show the complete solution to the problem of which are all the initial pure states and the projective measurements that allow the global saturation of the QIB, without the knowledge of the true value of the parameter, when the information about the parameter is encoded in the system by a unitary process.</font></div><div><br></div></div><div><div><div><div style="color:rgb(0,0,0);font-family:Helvetica;font-size:16px"><br></div></div></div></div></div>
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