A1: Generate State One

Editorial

Quantum computers use the concept of "quantum gates" to manipulate the state of qubits.

To flip a bit in the computational basis states of a quantum state, we can use the $X$ gate, which is a fundamental type of quantum gate.

Therefore, we can solve this problem by applying the $X$ gate to the qubit:

Sample Code

Below is a sample code:

from qiskit import QuantumCircuit
 
 
def solve() -> QuantumCircuit:
    qc = QuantumCircuit(1)
 
    # Apply X gate to the 1st qubit (index 0)
    qc.x(0)
 
    return qc

Alternatively, the quantum gate can be applied using a slightly different syntax:

from qiskit import QuantumCircuit
from qiskit.circuit.library import XGate
 
 
def solve() -> QuantumCircuit:
    qc = QuantumCircuit(1)
 
    qc.append(XGate(), [0])
 
    return qc

Supplements

• The $X$ gate can be thought of as a quantum circuit version of the $\mathrm{NOT}$ gate in classical circuits. (The $X$ gate is sometimes referred to as the $\mathrm{NOT}$ gate).