Default User Info
Per Amazon recommendations, the default user for the AMI is dynamically generated based on the EC2 Instance ID. Thus, the user name will be different for each instance you launch. In addition, the password will also be dynamically generated by amazon and will be the Intance ID of your server.
The user name format will be a in the format:
Your instance id will be the password. To log into the server, either try the browser and navigate to the IP address of your instance and/or follow the instructions in the QU4RTET UI manual and verify that you can connect.
Getting the Instance ID and Reservation ID
Select your running instance in the AWS console. At the bottom of the page, on the Description tab you will see the Instance ID at the top left and the Reservation value at the bottom right.