QuTech Quantum Network Explorer MCH2022 Workshop

Welcome to QuTech's Quantum Network Explorer MCH2022 Workshop!

This workshop consists of two parts;

First, a basic introduction to quantum networks. Here, the basic building blocks of a quantum internet are introduced: quantum bits (qubits), entanglement, and quantum repeaters. This is presented live, but the slides are included in this repository.

Secondly, to illustrate these concepts, we will go through an implementation of a simple Quantum Key Distribution (QKD) application whereby Alice and Bob create a quantum-secured secret key which they can use to encrypt their communication. This will be done in Python using the tools available on the Quantum Network Explorer. The rest of this README contains the instructions for this part.

You can proceed in two ways:

1. Install the pre-requisites and then follow further instructions on the screen.
2. Install the pre-requisites and learn how to create applications, create experiments, and run experiments (all documented in this README.md below). Then implement the QKD protocol yourself based on the protocol description in the included slides. You may still find it helpful to follow the on screen instructions for creating applications and running experiments.

Pre-requisites

Firstly, the recommended OS for this workshop is Linux. If you are using Windows, please install Linux in a virtual machine or enable Bash on Ubuntu. MacOS in principle should work, but it often causes issues due to squidasm's dependencies. You may try your luck, but you are advised to install Linux in a virtual machine.

Secondly, you will need Python installed on your machine for this challenge.

CRITICAL: USE A PYTHON VERSION <= 3.9 --- DO NOT USE PYTHON 3.10.

The quantum network simulator, NetSquid, has not been updated for Python 3.10 yet.

Before continuing, it is recommended that you set up and work in a Python Virtual Environment. For more information, please see this tutorial. In addition to isolating your environment, it will also allow you to use an older Python version without having to uninstall Python 3.10 (if you have it). It is assumed from this point, that you are running in a Python virtual environment. The instructions should still work without a virtual environment, but they might be more difficult to debug in case something goes wrong.

In order to make use of QuTech's discrete simulator for quantum networks, NetSquid, you will need to first agree to the terms of service by registering on the community forum. Please register by following this link. Write down your chosen username and password, you will need it in a moment.

Next, you need to install SquidASM and the Quantum Network Explorer Application Development Kit (QNE-ADK). SquidASM is a NetQASM application processor built on top of the NetSquid quantum network simulator. You will use SquidASM to simulate your quantum network applications. The QNE-ADK offers a CLI interface for creating and running network experiments.

You can install both easily by running the following commands(you will be prompted for your username and password that you chose earlier):

Run the following commands:

pip3 install -e "git+https://github.com/QuTech-Delft/qne-adk.git@a125b2d27f1e5fef2822329cf824b18e22e9d00e#egg=qne-adk"
pip3 install squidasm==0.9.0 --extra-index-url https://pypi.netsquid.org

You can verify the QNE ADK installation by running

qne --help

Creating the application

First, you need to create the application which contains the source code directory. To create the application directory, please run

qne application create qkd alice bob

This will create an application called qkd consisting of two programs, alice and bob, that will run on separate nodes. You can choose the application name, as well as the node names, to be whatever you wish.

You will mainly be writing code in qkd/src/app_alice.py and qkd/src/app_bob.py. For more information about the directory structure and how to configure the application, please refer to the application configuration guide. For more information on options available through the CLI, please consult qne application --help.

Creating an experiment

An application is not very useful if it does not run on some network as part of some kind of experiment. To run your application, you first need to create an experiment. To create an experiment, please run

qne experiment create exp qkd randstad

This creates an experiment called exp running your application called qkd on a pre-configured network called randstad. The Randstad is an area in the Netherlands consisting primarily of the four largest Dutch cities (Amsterdam, Rotterdam, The Hague, and Utrecht) and their surroundings. The details of the available networks, their nodes, and available channels can be found in the Randstad section on the network configuration page.

For more information about the directory structure and how to configure the application, please refer to the experiment configuration guide. For more information on options available through the CLI, please consult qne experiment --help.

Running your experiment

Once you have an experiment created you can run it with

qne experiment run exp --timeout 30

Where you replace exp with the experiment name you chose earlier, if it's different from exp.

You can view the results of the experiment in exp/results/processed.json or by running qne experiment results exp --show (replacing exp with your experiment name if necessary). The results found at the top under round_result contain the contents of the dictionaries returns by app_alice.py and app_bob.py.

Iterating on your application

Once created you can rerun the experiment as many times as you wish.

DO NOT MODIFY the source files in the experiment directory. They are overwritten with every experiment run.

If you need to change the application code, make sure you change it in the application directory qkd/src. These files will be copied over to the experiment directory with every run.

To configure your experiment, you can modify the experiment.json file in your experiment directory. You will want to pay particular attention to the roles entry which identify the nodes where your alice and bob applications are run. By default this will be amsterdam and leiden for the randstad network. Therefore, the parameters of the relevant quantum channel for your application are in the entry identified by the slug amsterdam-leiden.

Please see experiment configuration for more details on how to use this file.

Application example

It may be useful to go through an application example to see how to write a quantum network application. To see such an example, please see this application example.

NetQASM documentation

As you will have seen from the application example, applications are written using the NetQASM SDK. For detailed documentation about the available functionality, please see the documentation page, and in particular netqasm.sdk.

You may also want to read the paper introducing NetQASM.