<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif">On Wed, Jun 13, 2018 at 10:03 PM, Adrian Tymes <<a href="mailto:atymes@gmail.com">atymes@gmail.com</a>> wrote:</span></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif"><br></span></div>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex" class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><font size="4">>> Given that Preskill is one of the world's leading experts on quantum information and is the Richard J Feynman Professor of Theoretical Physics at the California Institute of Technology</font></blockquote></blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> </blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">> ...<i>is an appeal to authority, and says nothing about the statements to which I objected.</i></blockquote><div><br></div><div><font size="4">An appeal to authority is not always without merit. If a professor of physics at Caltech says something about physics and Adrian Tymes says he's dead wrong and is just spewing pablum I think it is a tad more likely that Mr. Tymes has misunderstood the professor than that the professor has misunderstood physics. </font></div><div><font size="4"><br></font></div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><i>> Anything that is initially shocking fades from that status as it becomes more familiar. This is true even of quantum theory.</i></blockquote>
<p class="gmail-p1"><font size="4">I guess you're smarter than Feynman because he admitted me didn't understand quantum mechanics and didn't think anybody else did either. But then he never met you.</font></p>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex" class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><font size="4">>> That is the simplest possible example of quantum entanglement involving a single Qbit, Preskill was talking about far more complex systems where thousands or millions of Qbits are entangled, the sort of thing you'd need for a quantum computer.</font></blockquote></blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> </blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><i>>And? Each and every one of them is entangled with another particle; perhaps some pairs might be among that thousands or millions. This does not render the whole collection immeasurable.</i></blockquote><div> </div>
<font size="4">Preskill never said the information in the whole collection was immeasurable, if it was it would be useless for quantum computers; he was trying to explain how to make things more robust with quantum error correction; if the particles are entangled in a clever way and the outside environment interacts with just one particle in a many particle system the quantum information in the entire system will not be lost. And that’s vitally important because you’re never going to able to isolate the computer completely from interacting with the environment. </font><div><br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><i>> Unless he is trying to redefine the term "quantum entanglement". If so, that is far closer to "hyping up the spooky and mysterious” than "clearly explaining", and thus is not worth listening to if one is<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> </div>seeking an explanation.</i></blockquote><div><br></div>
<p class="gmail-p1"><font size="4">Nobody has an explanation why things behave the way they do in the quantum world, but some people know rules that allow them to make statistical predictions about what will happen. Nobody is very happy about these rules because they make little sense and would be universally rejected except for one thing, they work. In fact most physicists have given up trying to figure out why they work and thus aren’t interested in Copenhagen or Many Worlds, they are adherents of the “Shut Up And Calculate” quantum interpretation. A quantum computer engineer need not understand why the rules work he just needs to know that they do.</font></p>
<p class="gmail-p2"><font size="4"><br></font></p>
<div><font size="4">John K Clark </font><br></div>
<p class="gmail-p2"><br></p>
If you always assume you know more than your teacher how can you ever learn? I think you could use a dash of humility<br><br>, maybe just maybe other people know things you don't.<br><br>John K Clark </div></div>