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48 | 48 | 2, |
49 | 49 | None, |
50 | 50 | 'properties-of-a-measurement'), |
51 | | - ('Entanglement', 2, None, 'entanglement'), |
52 | 51 | ('Basic properties of hermitian operators', |
53 | 52 | 2, |
54 | 53 | None, |
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175 | 174 | <!-- navigation toc: --> <li><a href="#new-zoom-link" style="font-size: 80%;">New zoom link</a></li> |
176 | 175 | <!-- navigation toc: --> <li><a href="#measurements" style="font-size: 80%;">Measurements</a></li> |
177 | 176 | <!-- navigation toc: --> <li><a href="#properties-of-a-measurement" style="font-size: 80%;">Properties of a measurement</a></li> |
178 | | - <!-- navigation toc: --> <li><a href="#entanglement" style="font-size: 80%;">Entanglement</a></li> |
179 | 177 | <!-- navigation toc: --> <li><a href="#basic-properties-of-hermitian-operators" style="font-size: 80%;">Basic properties of hermitian operators</a></li> |
180 | 178 | <!-- navigation toc: --> <li><a href="#the-pauli-matrices-again" style="font-size: 80%;">The Pauli matrices again</a></li> |
181 | 179 | <!-- navigation toc: --> <li><a href="#spectral-decomposition" style="font-size: 80%;">Spectral Decomposition</a></li> |
@@ -341,28 +339,14 @@ <h2 id="properties-of-a-measurement" class="anchor">Properties of a measurement |
341 | 339 | us now look at other types of operations we can make on qubit states. |
342 | 340 | </p> |
343 | 341 |
|
344 | | -<!-- !split --> |
345 | | -<h2 id="entanglement" class="anchor">Entanglement </h2> |
346 | | - |
347 | | -<p>In order to study entanglement and why it is so important for quantum |
348 | | -computing, we need to introduce some basic measures and useful |
349 | | -quantities. These quantities are the spectral decomposition of |
350 | | -hermitian operators, how these are then used to define measurements |
351 | | -and how we can define so-called density operators (matrices). These |
352 | | -are all quantities which will become very useful when we discuss |
353 | | -entanglement and in particular how to quantify it. In order to define |
354 | | -these quantities we need first to remind ourselves about some basic linear |
355 | | -algebra properties of hermitian operators and matrices. |
356 | | -</p> |
357 | | - |
358 | 342 | <!-- !split --> |
359 | 343 | <h2 id="basic-properties-of-hermitian-operators" class="anchor">Basic properties of hermitian operators </h2> |
360 | 344 |
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361 | 345 | <p>The operators we typically encounter in quantum mechanical studies are</p> |
362 | 346 | <ol> |
363 | 347 | <li> Hermitian (self-adjoint) meaning that for example the elements of a Hermitian matrix \( \boldsymbol{U} \) obey \( u_{ij}=u_{ji}^* \).</li> |
364 | 348 | <li> Unitary \( \boldsymbol{U}\boldsymbol{U}^{\dagger}=\boldsymbol{U}^{\dagger}\boldsymbol{U}=\boldsymbol{I} \), where \( \boldsymbol{I} \) is the unit matrix</li> |
365 | | -<li> The oparator \( \boldsymbol{U} \) and its self-adjoint commute (often labeled as normal operators), that is \( [\boldsymbol{U},\boldsymbol{U}^{\dagger}]=0 \). An operator is <b>normal</b> if and only if it is diagonalizable. A Hermitian operator is normal.</li> |
| 349 | +<li> The operator \( \boldsymbol{U} \) and its self-adjoint commute (often labeled as normal operators), that is \( [\boldsymbol{U},\boldsymbol{U}^{\dagger}]=0 \). An operator is <b>normal</b> if and only if it is diagonalizable. A Hermitian operator is normal.</li> |
366 | 350 | </ol> |
367 | 351 | <p>Unitary operators in a Hilbert space preserve the norm and orthogonality. If \( \boldsymbol{U} \) is a unitary operator acting on a state \( \vert \psi_j\rangle \), the action of</p> |
368 | 352 |
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@@ -814,7 +798,7 @@ <h2 id="extending-the-expressions" class="anchor">Extending the expressions </h2 |
814 | 798 | p(x)=\sum_{i=0}^{n-1}p_i\boldsymbol{P}_{\psi_i(x)}, |
815 | 799 | $$ |
816 | 800 |
|
817 | | -<p>where \( p_i \) are the probabilities of a specific outcome. Add later a digression on marginal probabilities.</p> |
| 801 | +<p>where \( p_i \) are the probabilities of a specific outcome. </p> |
818 | 802 |
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819 | 803 | <p>With these prerequisites we are now ready to introduce the density matrices, or density operators.</p> |
820 | 804 |
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