Please see the output of the two following Qiskit programs.
Program 1:
qc = QuantumCircuit(3, 3)
from qiskit.providers.aer import AerSimulator
sim = AerSimulator() # make new simulator object
# Create quantum circuit with 6 qubits and 6 classical bits:
qc = QuantumCircuit(6, 6)
# BELOW LINE IS COMMENTED
#qc.x([3,4,5]) # Perform X-gates on qubits 3,4,5
# measure qubits 0,1,2,3,4,5 to classical bits 0,1,2,3,4,5 respectively
qc.measure([0,1,2,3,4,5],[0,1,2,3,4,5])
qc.draw() # returns a drawing of the circuit
job = sim.run(qc) # run the experiment
result = job.result() # get the results
result.get_counts() # interpret the results as a "counts" dictionary
OUTPUT: {'000000': 1024}
Program 2:
from qiskit import QuantumCircuit
qc = QuantumCircuit(3, 3)
from qiskit.providers.aer import AerSimulator
sim = AerSimulator() # make new simulator object
# Create quantum circuit with 6 qubits and 6 classical bits:
qc = QuantumCircuit(6, 6)
qc.x([3,4,5]) # Perform X-gates on qubits 3,4,5
# measure qubits 0,1,2,3,4,5 to classical bits 0,1,2,3,4,5 respectively
qc.measure([0,1,2,3,4,5],[0,1,2,3,4,5])
qc.draw() # returns a drawing of the circuit
job = sim.run(qc) # run the experiment
result = job.result() # get the results
result.get_counts() # interpret the results as a "counts" dictionary
OUTPUT: {'111000': 1024}
I am not able to make sense of the output. It's as if the output is mapped to the wrong bits. I found this example is on https://learn.qiskit.org/course/introduction/the-atoms-of-computation
