Getting started with your QMI
Once you've signed up and created an account for Quantum Cloud Services, you'll receive a dedicated Quantum Machine Image (QMITM). Your QMI comes pre-configured with the ForestTM SDK to develop hybrid quantum-classical programs, and the QCS command-line interface to easily schedule and manage reservations on Rigetti's quantum devices.
The Forest SDK includes pyQuil (a python library for hybrid quantum-classical programs), the QVM Simulator, and the Quil Compiler. Read the Forest™ SDK documentation to learn more.
To get started, you'll need to authenticate to your Quantum Machine Image using the SSH protocol. This allows you to establish a secure connection between your local computer and your QMI. Once you're connected, we'll run a simple quantum coin flip program to test that everything's working.
- Checking for existing SSH keys
Prior to generating a new SSH key, check to see if you have any existing SSH keys. We love GitHub's guide for this—check it out here.
- Generating a new SSH key and adding it to the ssh-agent
If you don't have an existing SSH key, you can generate a new SSH key and add it to the ssh-agent. We love GitHub's guide for this—check it out here. Don't forget to add your SSH key to the ssh-agent.
- Adding a new SSH key to your QCS account
To use your new (or existing) SSH key for QCS, you'll need to add it to your QCS account.
First, copy your SSH key to your clipboard by opening your terminal, and paste the following command:
pbcopy < ~/.ssh/id_rsa.pub
Note: If you've created a custom filename for your SSH key (i.e. it is not named id_rsa.pub), then modify the above pbcopy command to match your custom filename.
Locate the hidden .ssh folder, open the file in your favorite text editor, and copy its contents to your clipboard.
Once you've copied the contents of your id_rsa.pub file (i.e. your public SSH key) to your clipboard, log in to your QCS Dashboard, and navigate to the Account > SSH Keys page. Paste in your SSH key.
Connecting to your QMI with SSH
Once you've successfully generated an SSH key and added it to your QCS account, you're ready to connect to your QMI.
While logged in to your QCS dashboard, locate the card labeled Quantum Machine Image. Click on the COPY button.
Open your Terminal and paste in your clipboard.
Note: if you receive the following prompt "Are you sure you want to continue connecting (yes/no)?," then confirm by entering yes.
Congrats! You're now connected to your QMI—you should see the following welcome message in your terminal:
If you encounter a Permission denied issue, try repeating the steps above to generate an SSH key and add it to the ssh-agent.
If you've renamed your id_rsa and id_rsa.pub files, you'll need to either revert their names back to the original defaults, or instead of copying the SSH command that's provided in your Dashboard, use the following command instead:
ssh -i ~/.ssh/<YOUR_PRIVATE_KEY> forest@<IP-ADDRESS>
If you continue to encounter issues connecting to your QMI, please contact us at firstname.lastname@example.org.
Run your first program
To execute your first program on your QMI, we will run a simple quantum coin-toss program using the QVM simulator. This program prepares a quantum state which is in an equal superposition of the |0> (heads) and |1> (tails) states on three separate qubits (coins). It uses quantum mechanics to randomly select between heads and tails, similar to flipping a coin.
This program, with the filename hello_qmi.py, is already included in the home directory of your QMI (once you've connected to your QMI, type ls -a to list all files).
To execute it, first launch a virtual environment:
Then, simply run:
You should see an output similar to the following:
You can see that 3 qubits (each column) gave random results for this experiment over 10 coin flips (each row).
If you run this program many times, you will see different random results each time, but the percentage of results which are 0 or 1 will each approach 50%, like a fair coin.
We invite you to look inside hello_qmi.py to see how the program was built and executed using pyQuil. We've included verbose comments to explain each step. You can quickly do this with the following command:
Great! Your QMI is now set up and you've used it to successfully simulate a quantum program. Check out the Forest™ SDK documentation to develop your own program, and then after testing it on the QVM simulator, learn how to use the command-line interface to execute your program on the real quantum hardware.