This circuit implements a basic Quantum Phase Estimation algorithm with a fixed phase of 0.25 using 3 qubits and 2 classical bits.
```python
from qiskit import QuantumCircuit
import numpy as np
# Create a QuantumCircuit with 3 qubits and 2 classical bits
qc = QuantumCircuit(3, 2)
# Initialize the eigenstate qubit in |1⟩
qc.x(2)
# Apply Hadamard gates to the counting qubits
qc.h([0, 1])
# Apply controlled unitary operations corresponding to the phase e^(2πi*θ) with θ=0.25
qc.cp(2 * np.pi * 0.5, 0, 2) # Control qubit 0, target qubit 2
qc.cp(2 * np.pi * 0.25, 1, 2) # Control qubit 1, target qubit 2
# Apply inverse Quantum Fourier Transform on the counting qubits
qc.h(1)
qc.cp(-np.pi/2, 0, 1)
qc.h(0)
# Measure the counting qubits
qc.measure([0, 1], [0, 1])
```'Failed to run program: \'409 Client Error: Conflict for url: https://api.quantum.ibm.com/runtime/jobs. {"errors":[{"message":"You have reached the limit of 3 pending jobs. Please wait for a job to complete or cancel one before submitting anything new.","code":3458,"solution":"Wait until some previous jobs were finished. You can cancel pending jobs to run new jobs.","more_info":"https://docs.quantum-computing.ibm.com/errors"}]}\''