Default value for a state created by QuantumRegister

Question

What's the default value for a state created by QuantumRegister(1,'name_of_the_register')? Is it a $|0\rangle$ or a $|1\rangle$?

Answer 1

Here's the source code for quantumregister.py and quantumcircuit.py.

The default is $|0\rangle$. The code goes like:

from qiskit import QuantumCircuit, QuantumRegister
qr = QuantumRegister(1) 
circuit = QuantumCircuit(qr) 

By the way, if you're just beginning with Qiskit, you could check out Dr. Moran's textbook (this specific example is covered in chapter 5, ~p. 83).