diff --git a/_book/Introduction-to-Quantum-Computing.epub b/_book/Introduction-to-Quantum-Computing.epub index 52557a79d2dd57a14ecf3a4f900c852e98704af3..52f85e6cd739967f40d7f3f80e69530ae4c49d8e 100644 Binary files a/_book/Introduction-to-Quantum-Computing.epub and b/_book/Introduction-to-Quantum-Computing.epub differ diff --git a/_book/Introduction-to-Quantum-Computing.pdf b/_book/Introduction-to-Quantum-Computing.pdf index ee3710b1ff9ea0c9cb6f4f0f56c97d4f04d94b1f..5f2166183103d62f4c0e23370b6864c911d79021 100644 Binary files a/_book/Introduction-to-Quantum-Computing.pdf and b/_book/Introduction-to-Quantum-Computing.pdf differ diff --git a/_book/probabilisticSystems.html b/_book/probabilisticSystems.html index 740fa9b7ba196a1f16bb8267b02dc4be24914d76..ea3d7787b93152cd98ed270cf065c8ed18957b38 100644 --- a/_book/probabilisticSystems.html +++ b/_book/probabilisticSystems.html @@ -193,7 +193,7 @@ window.Quarto = { <h2 id="toc-title">Table of contents</h2> <ul> - <li><a href="#deterministic-classical-possibilities" id="toc-deterministic-classical-possibilities" class="nav-link active" data-scroll-target="#deterministic-classical-possibilities"><span class="header-section-number">2.1</span> Deterministic (classical) possibilities</a></li> + <li><a href="#deterministic-possibilities" id="toc-deterministic-possibilities" class="nav-link active" data-scroll-target="#deterministic-possibilities"><span class="header-section-number">2.1</span> Deterministic possibilities</a></li> <li><a href="#probability-distribution" id="toc-probability-distribution" class="nav-link" data-scroll-target="#probability-distribution"><span class="header-section-number">2.2</span> Probability distribution</a></li> <li><a href="#probabilistic-processes" id="toc-probabilistic-processes" class="nav-link" data-scroll-target="#probabilistic-processes"><span class="header-section-number">2.3</span> Probabilistic processes</a> <ul class="collapse"> @@ -225,9 +225,9 @@ window.Quarto = { <p>To describe a quantum computer mathematically, we can do math similar to the known topic of probabilistic systems. We therefore first look into describing a probabilistic system.</p> -<section id="deterministic-classical-possibilities" class="level2" data-number="2.1"> -<h2 data-number="2.1" class="anchored" data-anchor-id="deterministic-classical-possibilities"><span class="header-section-number">2.1</span> Deterministic (classical) possibilities</h2> -<p>At first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be <em>heads</em> or <em>tails</em> and for a dice this could be the labels of the different sides. We call these possibilities <em>classical possibilities</em>. Note that we will only be using a <em>finite</em> number of possibilities.</p> +<section id="deterministic-possibilities" class="level2" data-number="2.1"> +<h2 data-number="2.1" class="anchored" data-anchor-id="deterministic-possibilities"><span class="header-section-number">2.1</span> Deterministic possibilities</h2> +<p>At first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be <em>heads</em> or <em>tails</em> and for a dice this could be the labels of the different sides. We call these possibilities <em>deterministic possibilities</em>. Note that we will only be using a <em>finite</em> number of possibilities.</p> <div class="callout callout-style-simple callout-tip no-icon callout-titled"> <div class="callout-header d-flex align-content-center"> <div class="callout-icon-container"> @@ -238,13 +238,13 @@ Example: Random 2-bit number </div> </div> <div class="callout-body-container callout-body"> -<p>Imagine you have a random number generator, which outputs 2-bit numbers. The classical possibilities of this generator are <span class="math inline">\(00\)</span>, <span class="math inline">\(01\)</span>, <span class="math inline">\(10\)</span> and <span class="math inline">\(11\)</span>.</p> +<p>Imagine you have a random number generator, which outputs 2-bit numbers. The deterministic possibilities of this generator are <span class="math inline">\(00\)</span>, <span class="math inline">\(01\)</span>, <span class="math inline">\(10\)</span> and <span class="math inline">\(11\)</span>.</p> </div> </div> </section> <section id="probability-distribution" class="level2" data-number="2.2"> <h2 data-number="2.2" class="anchored" data-anchor-id="probability-distribution"><span class="header-section-number">2.2</span> Probability distribution</h2> -<p>Next, we need to assign each possibility a probability. We write this as <span class="math inline">\(\Pr[x]=p\)</span> where <span class="math inline">\(p \in [0,1]\)</span> is the probability of the classical possibility <span class="math inline">\(x\)</span>.</p> +<p>Next, we need to assign each possibility a probability. We write this as <span class="math inline">\(\Pr[x]=p\)</span> where <span class="math inline">\(p \in [0,1]\)</span> is the probability of the deterministic possibility <span class="math inline">\(x\)</span>.</p> <div class="callout callout-style-simple callout-tip no-icon callout-titled"> <div class="callout-header d-flex align-content-center"> <div class="callout-icon-container"> @@ -271,7 +271,7 @@ Example: Coin flip </div> </div> </div> -<p>This vector has <span class="math inline">\(n\)</span> entries, where each entry corresponds to a classical possibility <span class="math inline">\(X\)</span> and the probability of <span class="math inline">\(X\)</span> is <span class="math inline">\(\Pr[X] = d_i\)</span>. The sum over all probabilities has to be <span class="math inline">\(1\)</span> and each entry needs to be nonnegative in order to be a valid probability.</p> +<p>This vector has <span class="math inline">\(n\)</span> entries, where each entry corresponds to a deterministic possibility <span class="math inline">\(X\)</span> and the probability of <span class="math inline">\(X\)</span> is <span class="math inline">\(\Pr[X] = d_i\)</span>. The sum over all probabilities has to be <span class="math inline">\(1\)</span> and each entry needs to be nonnegative in order to be a valid probability.</p> <div class="callout callout-style-simple callout-tip no-icon callout-titled"> <div class="callout-header d-flex align-content-center"> <div class="callout-icon-container"> @@ -295,7 +295,7 @@ Example (continued): Random 2-bit number </div> </div> <div class="callout-body-container callout-body"> -<p>Recall your random 2-bit number generator from above. Imagine your generator outputs each classical possibility with equal probability, except for the possibility <span class="math inline">\(00\)</span>, which is never generated. The corresponding probability distribution would be <span class="math display">\[ +<p>Recall your random 2-bit number generator from above. Imagine your generator outputs each deterministic possibility with equal probability, except for the possibility <span class="math inline">\(00\)</span>, which is never generated. The corresponding probability distribution would be <span class="math display">\[ d_{\text{2-bit}} = \begin{pmatrix} 0 \\ \frac{1}{3}\\ \frac{1}{3} \\ \frac{1}{3} \end{pmatrix} \]</span></p> </div> @@ -304,7 +304,7 @@ d_{\text{2-bit}} = \begin{pmatrix} 0 \\ \frac{1}{3}\\ \frac{1}{3} \\ \frac{1}{3} <section id="probabilistic-processes" class="level2" data-number="2.3"> <h2 data-number="2.3" class="anchored" data-anchor-id="probabilistic-processes"><span class="header-section-number">2.3</span> Probabilistic processes</h2> <p>With a probability distribution, we can only describe the probabilities of possibilities without any knowledge of a prior state. We therefore add another element to our toolbox of probabilistic systems called a <em>probabilistic process</em>.</p> -<p>A probabilistic process is a collection of <span class="math inline">\(n\)</span> probability distributions, where for each classical possibility <span class="math inline">\(i\)</span> there is a probability distribution <span class="math inline">\(a_i\)</span>. This means, that if the system is in classical possibility <span class="math inline">\(i\)</span> before the process is applied, the system will afterwards be distributed according to <span class="math inline">\(a_i\)</span>. We can write this as a matrix, where each column is a probability distribution <span class="math inline">\(a_i\)</span>.</p> +<p>A probabilistic process is a collection of <span class="math inline">\(n\)</span> probability distributions, where for each deterministic possibility <span class="math inline">\(i\)</span> there is a probability distribution <span class="math inline">\(a_i\)</span>. This means, that if the system is in deterministic possibility <span class="math inline">\(i\)</span> before the process is applied, the system will afterwards be distributed according to <span class="math inline">\(a_i\)</span>. We can write this as a matrix, where each column is a probability distribution <span class="math inline">\(a_i\)</span>.</p> <div class="callout callout-style-simple callout-note no-icon"> <div class="callout-body d-flex"> <div class="callout-icon-container"> @@ -328,7 +328,7 @@ Example (continued): Random 2-bit number </div> </div> <div class="callout-body-container callout-body"> -<p>Imagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of <span class="math inline">\(\frac{1}{3}\)</span>. The probability distributions for each of the classical possibility would then be <span class="math display">\[ +<p>Imagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of <span class="math inline">\(\frac{1}{3}\)</span>. The probability distributions for each of the deterministic possibility would then be <span class="math display">\[ a_{00} = \begin{pmatrix} \frac{2}{3} \\ 0 \\ 0 \\ \frac{1}{3} \end{pmatrix}, a_{01} =\begin{pmatrix} 0 \\ \frac{2}{3} \\ \frac{1}{3} \\ 0 \end{pmatrix}, a_{10} =\begin{pmatrix} 0 \\ \frac{1}{3} \\ \frac{2}{3} \\ 0 \end{pmatrix}, a_{11} = \begin{pmatrix} \frac{1}{3} \\ 0 \\ 0 \\ \frac{2}{3} \end{pmatrix} \]</span> From this we can construct the process as a matrix from these processes as follows: <span class="math display">\[ A_{\text{flip}} = \begin{pmatrix} a_{00} & a_{01} & a_{10} & a_{11} \end{pmatrix} = \begin{pmatrix} \frac{2}{3} & 0 & 0 & \frac{1}{3} \\ 0 & \frac{2}{3} & \frac{1}{3} & 0 \\ 0 & \frac{1}{3} & \frac{2}{3} & 0 \\ \frac{1}{3} & 0 & 0 & \frac{2}{3} \end{pmatrix} diff --git a/_book/search.json b/_book/search.json index 0b0e61141909b609b5ebc8d9cf206d5d2398172e..9da50d9c4301dc5487fab2de2099a076e53a9efa 100644 --- a/_book/search.json +++ b/_book/search.json @@ -46,18 +46,18 @@ "href": "probabilisticSystems.html", "title": "2 Probabilistic systems", "section": "", - "text": "2.1 Deterministic (classical) possibilities\nAt first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be heads or tails and for a dice this could be the labels of the different sides. We call these possibilities classical possibilities. Note that we will only be using a finite number of possibilities.", + "text": "2.1 Deterministic possibilities\nAt first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be heads or tails and for a dice this could be the labels of the different sides. We call these possibilities deterministic possibilities. Note that we will only be using a finite number of possibilities.", "crumbs": [ "Quantum Basics", "<span class='chapter-number'>2</span> <span class='chapter-title'>Probabilistic systems</span>" ] }, { - "objectID": "probabilisticSystems.html#deterministic-classical-possibilities", - "href": "probabilisticSystems.html#deterministic-classical-possibilities", + "objectID": "probabilisticSystems.html#deterministic-possibilities", + "href": "probabilisticSystems.html#deterministic-possibilities", "title": "2 Probabilistic systems", "section": "", - "text": "Example: Random 2-bit number\n\n\n\nImagine you have a random number generator, which outputs 2-bit numbers. The classical possibilities of this generator are \\(00\\), \\(01\\), \\(10\\) and \\(11\\).", + "text": "Example: Random 2-bit number\n\n\n\nImagine you have a random number generator, which outputs 2-bit numbers. The deterministic possibilities of this generator are \\(00\\), \\(01\\), \\(10\\) and \\(11\\).", "crumbs": [ "Quantum Basics", "<span class='chapter-number'>2</span> <span class='chapter-title'>Probabilistic systems</span>" @@ -68,7 +68,7 @@ "href": "probabilisticSystems.html#probability-distribution", "title": "2 Probabilistic systems", "section": "2.2 Probability distribution", - "text": "2.2 Probability distribution\nNext, we need to assign each possibility a probability. We write this as \\(\\Pr[x]=p\\) where \\(p \\in [0,1]\\) is the probability of the classical possibility \\(x\\).\n\n\n\n\n\n\nExample: Coin flip\n\n\n\nFor a coin flip the probability of heads would be \\(\\Pr[\\text{heads}] = \\frac{1}{2}\\) and the probability for tails would be \\(\\Pr[\\text{tails}] = \\frac{1}{2}\\).\n\n\nIf we combine all probabilities for all the possible outcomes and write them as a vector, we get a probability distribution.\n\n\n\n\n\n\n\nDefinition 2.1 (Probability distribution) A vector \\(d \\in \\mathbb{R}^n\\) is a valid probability distribution iff \\(\\sum d_i = 1\\) and \\(\\forall i\\) \\(d_i \\geq 0\\)\n\n\n\n\nThis vector has \\(n\\) entries, where each entry corresponds to a classical possibility \\(X\\) and the probability of \\(X\\) is \\(\\Pr[X] = d_i\\). The sum over all probabilities has to be \\(1\\) and each entry needs to be nonnegative in order to be a valid probability.\n\n\n\n\n\n\nExample (continued): Coin flip\n\n\n\nFor a coin flip the probability distribution would be \\(d_{\\text{coin}} \\in \\mathbb{R}^2\\) with \\(d = \\begin{pmatrix}\\frac{1}{2}\\\\ \\frac{1}{2} \\end{pmatrix}\\)\n\n\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nRecall your random 2-bit number generator from above. Imagine your generator outputs each classical possibility with equal probability, except for the possibility \\(00\\), which is never generated. The corresponding probability distribution would be \\[\nd_{\\text{2-bit}} = \\begin{pmatrix} 0 \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{1}{3} \\end{pmatrix}\n\\]", + "text": "2.2 Probability distribution\nNext, we need to assign each possibility a probability. We write this as \\(\\Pr[x]=p\\) where \\(p \\in [0,1]\\) is the probability of the deterministic possibility \\(x\\).\n\n\n\n\n\n\nExample: Coin flip\n\n\n\nFor a coin flip the probability of heads would be \\(\\Pr[\\text{heads}] = \\frac{1}{2}\\) and the probability for tails would be \\(\\Pr[\\text{tails}] = \\frac{1}{2}\\).\n\n\nIf we combine all probabilities for all the possible outcomes and write them as a vector, we get a probability distribution.\n\n\n\n\n\n\n\nDefinition 2.1 (Probability distribution) A vector \\(d \\in \\mathbb{R}^n\\) is a valid probability distribution iff \\(\\sum d_i = 1\\) and \\(\\forall i\\) \\(d_i \\geq 0\\)\n\n\n\n\nThis vector has \\(n\\) entries, where each entry corresponds to a deterministic possibility \\(X\\) and the probability of \\(X\\) is \\(\\Pr[X] = d_i\\). The sum over all probabilities has to be \\(1\\) and each entry needs to be nonnegative in order to be a valid probability.\n\n\n\n\n\n\nExample (continued): Coin flip\n\n\n\nFor a coin flip the probability distribution would be \\(d_{\\text{coin}} \\in \\mathbb{R}^2\\) with \\(d = \\begin{pmatrix}\\frac{1}{2}\\\\ \\frac{1}{2} \\end{pmatrix}\\)\n\n\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nRecall your random 2-bit number generator from above. Imagine your generator outputs each deterministic possibility with equal probability, except for the possibility \\(00\\), which is never generated. The corresponding probability distribution would be \\[\nd_{\\text{2-bit}} = \\begin{pmatrix} 0 \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{1}{3} \\end{pmatrix}\n\\]", "crumbs": [ "Quantum Basics", "<span class='chapter-number'>2</span> <span class='chapter-title'>Probabilistic systems</span>" @@ -79,7 +79,7 @@ "href": "probabilisticSystems.html#probabilistic-processes", "title": "2 Probabilistic systems", "section": "2.3 Probabilistic processes", - "text": "2.3 Probabilistic processes\nWith a probability distribution, we can only describe the probabilities of possibilities without any knowledge of a prior state. We therefore add another element to our toolbox of probabilistic systems called a probabilistic process.\nA probabilistic process is a collection of \\(n\\) probability distributions, where for each classical possibility \\(i\\) there is a probability distribution \\(a_i\\). This means, that if the system is in classical possibility \\(i\\) before the process is applied, the system will afterwards be distributed according to \\(a_i\\). We can write this as a matrix, where each column is a probability distribution \\(a_i\\).\n\n\n\n\n\n\n\nDefinition 2.2 (Probabilistic process) A matrix \\(A \\in \\mathbb{R}^{n\\times n}\\) is a valid probabilistic process iff for every column \\(a\\) of \\(A\\), \\(a\\) is a valid probability distribution.\n\n\n\n\nFrom Definition 2.1 we know that a valid probability distribution \\(a\\) has the properties \\(\\sum a_i = 1\\) and \\(\\forall i\\) \\(a_i \\geq 0\\), therefore a matrix \\(A\\) is a probabilistic process iff \\(A \\in \\mathbb{R}^{n \\times n}\\) with \\(\\sum a_i = 1\\) and \\(\\forall i\\) \\(a_i \\geq 0\\) . Such a matrix is also called a stochastic matrix.\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nImagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of \\(\\frac{1}{3}\\). The probability distributions for each of the classical possibility would then be \\[\na_{00} = \\begin{pmatrix} \\frac{2}{3} \\\\ 0 \\\\ 0 \\\\ \\frac{1}{3} \\end{pmatrix}, a_{01} =\\begin{pmatrix} 0 \\\\ \\frac{2}{3} \\\\ \\frac{1}{3} \\\\ 0 \\end{pmatrix}, a_{10} =\\begin{pmatrix} 0 \\\\ \\frac{1}{3} \\\\ \\frac{2}{3} \\\\ 0 \\end{pmatrix}, a_{11} = \\begin{pmatrix} \\frac{1}{3} \\\\ 0 \\\\ 0 \\\\ \\frac{2}{3} \\end{pmatrix}\n\\] From this we can construct the process as a matrix from these processes as follows: \\[\nA_{\\text{flip}} = \\begin{pmatrix} a_{00} & a_{01} & a_{10} & a_{11} \\end{pmatrix} = \\begin{pmatrix} \\frac{2}{3} & 0 & 0 & \\frac{1}{3} \\\\ 0 & \\frac{2}{3} & \\frac{1}{3} & 0 \\\\ 0 & \\frac{1}{3} & \\frac{2}{3} & 0 \\\\ \\frac{1}{3} & 0 & 0 & \\frac{2}{3} \\end{pmatrix}\n\\]\n\n\n\nApplying a probabilistic process\nHaving defined probability distributions and probabilistic processes, we can now combine these two elements and apply a probabilistic process on a probability distribution.\n\n\n\n\n\n\n\nDefinition 2.3 (Applying a probabilistic process) Given an initial probability distribution \\(x\\) and a probabilistic process \\(A\\), the result \\(y\\) of applying the process \\(A\\) is defined as \\[\ny = Ax\n\\]\n\n\n\n\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nRecall the 2-bit number generator and the bit flip from above. Imagine you would first draw a random 2-bit number from the generator and then run the bit flip device. We already know that the probability distribution of the generator is \\(M_\\text{2-bit}\\). Using \\(A_\\text{flip}\\) we can calculate the final probability distribution: \\[\nA_\\text{flip} \\cdot d_\\text{2-bit} = \\begin{pmatrix} \\frac{2}{3} & 0 & 0 & \\frac{1}{3} \\\\ 0 & \\frac{2}{3} & \\frac{1}{3} & 0 \\\\ 0 & \\frac{1}{3} & \\frac{2}{3} & 0 \\\\ \\frac{1}{3} & 0 & 0 & \\frac{2}{3} \\end{pmatrix}\\begin{pmatrix} 0 \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{1}{3} \\end{pmatrix} = \\begin{pmatrix} \\frac{1}{9} \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{2}{9} \\end{pmatrix}\n\\]", + "text": "2.3 Probabilistic processes\nWith a probability distribution, we can only describe the probabilities of possibilities without any knowledge of a prior state. We therefore add another element to our toolbox of probabilistic systems called a probabilistic process.\nA probabilistic process is a collection of \\(n\\) probability distributions, where for each deterministic possibility \\(i\\) there is a probability distribution \\(a_i\\). This means, that if the system is in deterministic possibility \\(i\\) before the process is applied, the system will afterwards be distributed according to \\(a_i\\). We can write this as a matrix, where each column is a probability distribution \\(a_i\\).\n\n\n\n\n\n\n\nDefinition 2.2 (Probabilistic process) A matrix \\(A \\in \\mathbb{R}^{n\\times n}\\) is a valid probabilistic process iff for every column \\(a\\) of \\(A\\), \\(a\\) is a valid probability distribution.\n\n\n\n\nFrom Definition 2.1 we know that a valid probability distribution \\(a\\) has the properties \\(\\sum a_i = 1\\) and \\(\\forall i\\) \\(a_i \\geq 0\\), therefore a matrix \\(A\\) is a probabilistic process iff \\(A \\in \\mathbb{R}^{n \\times n}\\) with \\(\\sum a_i = 1\\) and \\(\\forall i\\) \\(a_i \\geq 0\\) . Such a matrix is also called a stochastic matrix.\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nImagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of \\(\\frac{1}{3}\\). The probability distributions for each of the deterministic possibility would then be \\[\na_{00} = \\begin{pmatrix} \\frac{2}{3} \\\\ 0 \\\\ 0 \\\\ \\frac{1}{3} \\end{pmatrix}, a_{01} =\\begin{pmatrix} 0 \\\\ \\frac{2}{3} \\\\ \\frac{1}{3} \\\\ 0 \\end{pmatrix}, a_{10} =\\begin{pmatrix} 0 \\\\ \\frac{1}{3} \\\\ \\frac{2}{3} \\\\ 0 \\end{pmatrix}, a_{11} = \\begin{pmatrix} \\frac{1}{3} \\\\ 0 \\\\ 0 \\\\ \\frac{2}{3} \\end{pmatrix}\n\\] From this we can construct the process as a matrix from these processes as follows: \\[\nA_{\\text{flip}} = \\begin{pmatrix} a_{00} & a_{01} & a_{10} & a_{11} \\end{pmatrix} = \\begin{pmatrix} \\frac{2}{3} & 0 & 0 & \\frac{1}{3} \\\\ 0 & \\frac{2}{3} & \\frac{1}{3} & 0 \\\\ 0 & \\frac{1}{3} & \\frac{2}{3} & 0 \\\\ \\frac{1}{3} & 0 & 0 & \\frac{2}{3} \\end{pmatrix}\n\\]\n\n\n\nApplying a probabilistic process\nHaving defined probability distributions and probabilistic processes, we can now combine these two elements and apply a probabilistic process on a probability distribution.\n\n\n\n\n\n\n\nDefinition 2.3 (Applying a probabilistic process) Given an initial probability distribution \\(x\\) and a probabilistic process \\(A\\), the result \\(y\\) of applying the process \\(A\\) is defined as \\[\ny = Ax\n\\]\n\n\n\n\n\n\n\n\n\n\nExample (continued): Random 2-bit number\n\n\n\nRecall the 2-bit number generator and the bit flip from above. Imagine you would first draw a random 2-bit number from the generator and then run the bit flip device. We already know that the probability distribution of the generator is \\(M_\\text{2-bit}\\). Using \\(A_\\text{flip}\\) we can calculate the final probability distribution: \\[\nA_\\text{flip} \\cdot d_\\text{2-bit} = \\begin{pmatrix} \\frac{2}{3} & 0 & 0 & \\frac{1}{3} \\\\ 0 & \\frac{2}{3} & \\frac{1}{3} & 0 \\\\ 0 & \\frac{1}{3} & \\frac{2}{3} & 0 \\\\ \\frac{1}{3} & 0 & 0 & \\frac{2}{3} \\end{pmatrix}\\begin{pmatrix} 0 \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{1}{3} \\end{pmatrix} = \\begin{pmatrix} \\frac{1}{9} \\\\ \\frac{1}{3}\\\\ \\frac{1}{3} \\\\ \\frac{2}{9} \\end{pmatrix}\n\\]", "crumbs": [ "Quantum Basics", "<span class='chapter-number'>2</span> <span class='chapter-title'>Probabilistic systems</span>" diff --git a/_book/sitemap.xml b/_book/sitemap.xml index 0b12044e8367babbbe30336e7704587c5c82a15f..324f12b10f3a0de868c304f118da228ae250915e 100644 --- a/_book/sitemap.xml +++ b/_book/sitemap.xml @@ -14,14 +14,14 @@ </url> <url> <loc>https://qis.rwth-aachen.de/teaching/24ss/intro-quantum-computing/script/probabilisticSystems.html</loc> - <lastmod>2024-05-21T10:42:49.300Z</lastmod> + <lastmod>2024-05-21T12:51:48.377Z</lastmod> </url> <url> <loc>https://qis.rwth-aachen.de/teaching/24ss/intro-quantum-computing/script/Introduction-to-Quantum-Computing.pdf</loc> - <lastmod>2024-05-21T10:43:34.623Z</lastmod> + <lastmod>2024-05-21T12:52:36.889Z</lastmod> </url> <url> <loc>https://qis.rwth-aachen.de/teaching/24ss/intro-quantum-computing/script/Introduction-to-Quantum-Computing.epub</loc> - <lastmod>2024-05-21T10:44:01.453Z</lastmod> + <lastmod>2024-05-21T12:53:04.707Z</lastmod> </url> </urlset> diff --git a/probabilisticSystems.qmd b/probabilisticSystems.qmd index b5bace12e5554fe059f70b7fe4c61addcb755bc2..d4c9a68d5d53471f43e2c523f763d0de0b2001f8 100644 --- a/probabilisticSystems.qmd +++ b/probabilisticSystems.qmd @@ -1,17 +1,17 @@ # Probabilistic systems To describe a quantum computer mathematically, we can do math similar to the known topic of probabilistic systems. We therefore first look into describing a probabilistic system. -## Deterministic (classical) possibilities -At first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be *heads* or *tails* and for a dice this could be the labels of the different sides. We call these possibilities *classical possibilities*. Note that we will only be using a *finite* number of possibilities. +## Deterministic possibilities +At first we need to define all the different possible outcomes of our system. For example, for a coin flip this could be *heads* or *tails* and for a dice this could be the labels of the different sides. We call these possibilities *deterministic possibilities*. Note that we will only be using a *finite* number of possibilities. ::: {.callout-tip icon=false} ## Example: Random 2-bit number -Imagine you have a random number generator, which outputs 2-bit numbers. The classical possibilities of this generator are $00$, $01$, $10$ and $11$. +Imagine you have a random number generator, which outputs 2-bit numbers. The deterministic possibilities of this generator are $00$, $01$, $10$ and $11$. ::: ## Probability distribution -Next, we need to assign each possibility a probability. We write this as $\Pr[x]=p$ where $p \in [0,1]$ is the probability of the classical possibility $x$. +Next, we need to assign each possibility a probability. We write this as $\Pr[x]=p$ where $p \in [0,1]$ is the probability of the deterministic possibility $x$. ::: {.callout-tip icon=false} @@ -29,7 +29,7 @@ A vector $d \in \mathbb{R}^n$ is a valid probability distribution iff $\sum d_i ::: ::: -This vector has $n$ entries, where each entry corresponds to a classical possibility $X$ and the probability of $X$ is $\Pr[X] = d_i$. The sum over all probabilities has to be $1$ and each entry needs to be nonnegative in order to be a valid probability. +This vector has $n$ entries, where each entry corresponds to a deterministic possibility $X$ and the probability of $X$ is $\Pr[X] = d_i$. The sum over all probabilities has to be $1$ and each entry needs to be nonnegative in order to be a valid probability. ::: {.callout-tip icon=false} @@ -40,7 +40,7 @@ For a coin flip the probability distribution would be $d_{\text{coin}} \in \math ::: {.callout-tip icon=false} ## Example (continued): Random 2-bit number -Recall your random 2-bit number generator from above. Imagine your generator outputs each classical possibility with equal probability, except for the possibility $00$, which is never generated. The corresponding probability distribution would be +Recall your random 2-bit number generator from above. Imagine your generator outputs each deterministic possibility with equal probability, except for the possibility $00$, which is never generated. The corresponding probability distribution would be $$ d_{\text{2-bit}} = \begin{pmatrix} 0 \\ \frac{1}{3}\\ \frac{1}{3} \\ \frac{1}{3} \end{pmatrix} $$ @@ -49,7 +49,7 @@ $$ ## Probabilistic processes With a probability distribution, we can only describe the probabilities of possibilities without any knowledge of a prior state. We therefore add another element to our toolbox of probabilistic systems called a *probabilistic process*. -A probabilistic process is a collection of $n$ probability distributions, where for each classical possibility $i$ there is a probability distribution $a_i$. This means, that if the system is in classical possibility $i$ before the process is applied, the system will afterwards be distributed according to $a_i$. We can write this as a matrix, where each column is a probability distribution $a_i$. +A probabilistic process is a collection of $n$ probability distributions, where for each deterministic possibility $i$ there is a probability distribution $a_i$. This means, that if the system is in deterministic possibility $i$ before the process is applied, the system will afterwards be distributed according to $a_i$. We can write this as a matrix, where each column is a probability distribution $a_i$. ::: {.callout-note appearance="minimal" icon=false} ::: {.definition #def-prob-process} @@ -66,7 +66,7 @@ From @def-prob-distribution we know that a valid probability distribution $a$ ha ::: {.callout-tip icon=false} ## Example (continued): Random 2-bit number -Imagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of $\frac{1}{3}$. The probability distributions for each of the classical possibility would then be +Imagine a second device, which receives a 2-bit number as an input and flips both bits at the same time with a probability of $\frac{1}{3}$. The probability distributions for each of the deterministic possibility would then be $$ a_{00} = \begin{pmatrix} \frac{2}{3} \\ 0 \\ 0 \\ \frac{1}{3} \end{pmatrix}, a_{01} =\begin{pmatrix} 0 \\ \frac{2}{3} \\ \frac{1}{3} \\ 0 \end{pmatrix}, a_{10} =\begin{pmatrix} 0 \\ \frac{1}{3} \\ \frac{2}{3} \\ 0 \end{pmatrix}, a_{11} = \begin{pmatrix} \frac{1}{3} \\ 0 \\ 0 \\ \frac{2}{3} \end{pmatrix} $$