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Hello World: Your First Quantum Circuit

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Build a Bell state (two entangled qubits) and run it three ways:

  1. Ideal simulation — perfect results, no account needed
  2. Noisy simulation — simulates a real device, no account needed
  3. Real quantum hardware — requires an IBM Quantum account

Build the circuit​

from qiskit import QuantumCircuit

qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()

qc.draw(output="mpl")

Option 1: Ideal simulation (no account needed)​

Uses StatevectorSampler — a local simulator with perfect, noise-free results.

from qiskit.primitives import StatevectorSampler

result = StatevectorSampler().run([qc], shots=1024).result()
counts = result[0].data.meas.get_counts()
counts
from qiskit.visualization import plot_histogram
plot_histogram(counts)

Option 2: Noisy simulation (no account needed)​

Uses FakeManilaV2 — a local simulator that mimics a real IBM quantum device, including its noise characteristics. The circuit must first be transpiled (adapted) to the device's gate set and qubit connectivity.

from qiskit_ibm_runtime import SamplerV2
from qiskit_ibm_runtime.fake_provider import FakeManilaV2
from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager

backend = FakeManilaV2()
pm = generate_preset_pass_manager(backend=backend, optimization_level=1)
isa_qc = pm.run(qc)

result = SamplerV2(mode=backend).run([isa_qc], shots=1024).result()
counts = result[0].data.meas.get_counts()
counts
plot_histogram(counts)

Option 3: Real quantum hardware​

Requires an IBM Quantum account. See Setting up your IBM Quantum account for details.

Skip this cell if you've saved credentials in Settings or enabled Simulator Mode — they're auto-injected when you click Run. Running this cell with placeholder values will overwrite your configuration.

On other platforms, run this first to save credentials for the session:

from qiskit_ibm_runtime import QiskitRuntimeService

QiskitRuntimeService.save_account(
    token="<your-api-key>",
    instance="<your-crn>",
    overwrite=True
)

Note: Jobs on real hardware may take some time depending on queue times. If the cell is still running, you can check your job status and see the results at quantum.cloud.ibm.com/workloads.

from qiskit_ibm_runtime import QiskitRuntimeService, SamplerV2
from qiskit.transpiler.preset_passmanagers import generate_preset_pass_manager

service = QiskitRuntimeService()
backend = service.least_busy(operational=True, simulator=False)
print(f"Running on {backend.name}")

pm = generate_preset_pass_manager(backend=backend, optimization_level=1)
isa_qc = pm.run(qc)

result = SamplerV2(mode=backend).run([isa_qc], shots=1024).result()
counts = result[0].data.meas.get_counts()
counts
plot_histogram(counts)

What next?​

  • Tutorials — step-by-step guides on algorithms, error mitigation, transpilation, and more
  • Courses — structured learning paths from quantum basics to utility-scale computing
  • Local testing mode — run most notebooks without an IBM Quantum account