diff --git a/README.md b/README.md index b099993..f7f8556 100644 --- a/README.md +++ b/README.md @@ -51,8 +51,10 @@ For some lectures there is also some extra content. We'll cover it if there is t Four sets of take-home exercises set throughout the course. There will be hints sessions at 16:15 on the dates that these are set. Solutions will be presented after the exercises have been graded. -* [Exercise 1](exercises/Exercise1.ipynb): Set 01/10/2024, due 15/10/2024. -* [Exercise 2](exercises/Exercise2.ipynb): Set 15/10/2024, due 29/10/2024. +* [Exercise 1](exercises/Exercise1.ipynb): Set 01/10/2024, due 15/10/2024, Anatolii as TA. +* [Exercise 2](exercises/Exercise2.ipynb): Set 15/10/2024, due 29/10/2024, Anatolii as TA. +* [Exercise 3](exercises/Exercise3.ipynb): Set 29/10/2024, due 12/11/2024, Kacper as TA. + **Note: These exercises form 50% of your final grade** diff --git a/exercises/Exercise3.ipynb b/exercises/Exercise3.ipynb new file mode 100644 index 0000000..83f52f1 --- /dev/null +++ b/exercises/Exercise3.ipynb @@ -0,0 +1,74 @@ +{ + "cells": [ + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "# Exercise 3\n", + "\n", + "This sheet is about [density matrices](../QI_course/2_The_Qubit.pdf), [the partial trace](../QI_course/3_Quantum_Information.pdf) and [the Schmidt decomposition](../QI_course/6_Quantum_Correlations_part_1.pdf). Take a look at the linked materials to find out more." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [ + "## 1\n", + "\n", + "Given an abitrary single qubit state $a|0\\rangle +b|1\\rangle$:\n", + "\n", + "(a) Write down the correponding density matrix.\n", + "\n", + "(b) Write down the density matrix representing the effect of applying an $X$ with probability $q_x$, $Y$ with probability $q_y$ and $Z$ with probability $q_z$.\n", + "\n", + "(c) Write down the density matrix for representing the effect of replacing the state with $I/2$ with probability $p$.\n", + "\n", + "(d) For what values of $q_x$, $q_y$ and $q_z$ is the effect of (b) equivalent to that of (c)?\n", + "\n", + "## 2\n", + "\n", + "(a) Write down the density matrix of a single qubit which is in state $|0\\rangle$ with probability $2/3$ and $|+\\rangle$ with probability $1/3$.\n", + "\n", + "(b) Find a two qubit state such that one of the reduced density matrices is equal to the density matrix in (a).\n", + "\n", + "(c) Write down a density matrix for a state that is not entangled, but which has the same reduced density matrices as your answer for (b).\n", + "\n", + "## 3\n", + "\n", + "Consider the three qubit state $(|001\\rangle + |010\\rangle)+ |100\\rangle/\\sqrt{3}$.\n", + "\n", + "(a) What is the reduced density matrix for a single qubit in this state?\n", + "\n", + "(b) What is the reduced density matrix for a pair of qubits in this state?\n", + "\n", + "(c) Use the Schmidt decomposition to rewrite the state, with one qubit on one side of the bipartition and two qubits on the other." + ] + }, + { + "cell_type": "markdown", + "metadata": {}, + "source": [] + } + ], + "metadata": { + "kernelspec": { + "display_name": "Python 3", + "language": "python", + "name": "python3" + }, + "language_info": { + "codemirror_mode": { + "name": "ipython", + "version": 3 + }, + "file_extension": ".py", + "mimetype": "text/x-python", + "name": "python", + "nbconvert_exporter": "python", + "pygments_lexer": "ipython3", + "version": "3.9.1" + } + }, + "nbformat": 4, + "nbformat_minor": 4 +}