Qiskit Terra

2.4.1 verified Mon Apr 27 auth: no python

Qiskit is an open-source SDK for working with quantum computers at the level of circuits, transpilation, and pulse control. The qiskit-terra package is the foundational component, providing circuit construction, transpilation, simulation, and IBM Quantum backend access. As of version 2.x, the package is simply called 'qiskit' on PyPI (qiskit-terra is a legacy distribution). Current version: 2.4.1, with quarterly releases.

pip install qiskit

Common errors

error ModuleNotFoundError: No module named 'qiskit' ↓

cause Qiskit is not installed.

fix

pip install qiskit

error ModuleNotFoundError: No module named 'qiskit.extensions' ↓

cause qiskit.extensions was removed in Qiskit 1.0.

fix

Import gates directly: from qiskit.circuit.library import HGate, CXGate

error ImportError: cannot import name 'Aer' from 'qiskit' ↓

cause Aer was moved to a separate package in qiskit-terra 0.44.

fix

pip install qiskit-aer and import from qiskit_aer

error AttributeError: 'QuantumCircuit' object has no attribute 'qasm' ↓

cause The qasm() method was removed in Qiskit 1.0.

fix

Use qiskit.qasm2.dumps(circuit) or qiskit.qasm3.dumps(circuit)

Warnings

breaking Qiskit 1.0 removed many legacy modules: qiskit.tools, qiskit.quantum_info.random, qiskit.extensions, and more. Update imports and usage accordingly. ↓

fix Refer to the Qiskit 1.0 migration guide: https://docs.quantum.ibm.com/migration-guides/v1

deprecated Qiskit 2.x deprecated the use of the Qiskit Terra PyPI package name; use `qiskit` instead. ↓

fix Install via `pip install qiskit` (qiskit-terra may be for legacy compatibility only).

gotcha Aer is no longer part of qiskit-terra. Importing from qiskit.providers.aer will fail. You must install qiskit-aer separately. ↓

fix pip install qiskit-aer and import from qiskit_aer

gotcha The BasicAer backend was removed in Qiskit 1.0. Use BasicProvider from qiskit.providers.basic_provider instead. ↓

fix from qiskit.providers.basic_provider import BasicProvider

deprecated QuantumCircuit.draw() with the 'mpl' style may require matplotlib to be installed separately. ↓

fix pip install matplotlib, or use 'text' style

Install

pip install qiskit-terra

Imports

QuantumCircuit

wrong

from qiskit-terra import QuantumCircuit

correct

from qiskit import QuantumCircuit

qiskit-terra is not a package; use qiskit

transpile

wrong

from qiskit.compiler import transpile

correct

from qiskit import transpile

removed in Qiskit 1.0

Aer
wrong
```
from qiskit import Aer
```
correct
```
from qiskit_aer import Aer
```
Aer was removed from qiskit-terra in 0.44; install qiskit-aer separately

plot_histogram

wrong

from qiskit.tools.visualization import plot_histogram

correct

from qiskit.visualization import plot_histogram

qiskit.tools removed in Qiskit 1.0

Quickstart

Create a Bell state circuit and transpile for the built-in basic simulator.

from qiskit import QuantumCircuit
from qiskit import transpile
from qiskit.providers.basic_provider import BasicProvider

# Create a simple circuit
qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()

# Transpile for basic simulator
qc = transpile(qc, backend=BasicProvider().get_backend('basic_simulator'))
print(qc)