unitarylab/quantum-practices/qiskit

Qiskit - Quantum Computing Framework & Simulator

Overview

Qiskit is an open-source quantum computing framework developed by IBM that enables quantum circuit design, simulation, and execution on real quantum hardware. It provides a comprehensive Python-based ecosystem for quantum algorithm development, allowing researchers and practitioners to design, test, and deploy quantum algorithms across simulation backends and real quantum processors from IBM Quantum Experience.

Qiskit stands for Quantum Information Science Kit and serves as a bridge between high-level quantum algorithm concepts and low-level quantum hardware implementation, democratizing access to quantum computing resources.

Installation Guide

System Requirements

• Python Version: Python 3.8 or higher
• Operating Systems: Windows, macOS, Linux
• Memory: Minimum 4GB (8GB recommended for larger simulations)
• Processor: Any modern multi-core processor

Installation

The quickest way to install Qiskit:

pip install qiskit

For a complete installation including simulators and visualization:

pip install qiskit qiskit-aer qiskit-ibmq matplotlib

Quick Start

from qiskit import QuantumCircuit
from qiskit_aer import AerSimulator
qc = QuantumCircuit(2, 2)
qc.h(0)          # Hadamard gate creates superposition
qc.cx(0, 1)      # CNOT creates entanglement
qc.measure([0, 1], [0, 1])
result = AerSimulator().run(qc, shots=100).result()
print(result.get_counts(0))  # Output: {'00': 50, '11': 50}

This creates an entangled Bell state and runs it on a simulator!

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Visualization

Qiskit provides powerful visualization tools to help understand quantum circuits and results:

Circuit Diagrams

qc.draw('mpl')

State Vector Visualization

from qiskit.visualization import plot_state_city
plot_state_city(result.get_statevector(0))

Histogram Visualization

from qiskit.visualization import plot_histogram
plot_histogram(result.get_counts(0))

Key Features

1. Intuitive Circuit Design

• Standard quantum gates (Hadamard, CNOT, Pauli, Rotation gates)
• Parametric circuits for variational algorithms
• Circuit composition and mid-circuit measurements
• Multiple visualization formats (ASCII, LaTeX, PNG)

2. Multiple Simulators

• Statevector Simulator: Exact quantum state evolution
• QASM Simulator: Shot-based realistic simulation
• Unitary Simulator: Unitary matrix tracking
• GPU Acceleration: 10-50x speedup with NVIDIA GPU

3. Real Quantum Hardware

• Direct access to IBM Quantum processors (5 to 127 qubits)
• Cloud-based job submission and execution
• Real-time job status tracking and result retrieval

4. Noise and Error Modeling

• Realistic noise models from actual quantum hardware
• Depolarizing, amplitude damping, phase damping errors
• Gate errors and measurement errors
• Custom error channels support

5. Circuit Optimization

• Automatic multi-level optimization (levels 0-3)
• Topology mapping to hardware connectivity
• Gate decomposition to native gates
• Custom optimization pipelines

6. Algorithm Implementations

• Variational Quantum Eigensolver (VQE)
• Quantum Approximate Optimization Algorithm (QAOA)
• Grover's search algorithm
• Quantum phase estimation
• Pre-built algorithm library

7. Advanced Measurement

• Single-shot and statistical measurements
• Arbitrary Pauli observable measurement
• Quantum state tomography
• Process characterization
• Fidelity computation

8. Hybrid Quantum-Classical Computing

• Automatic gradient computation via parameter shift rule
• Integration with classical optimizers (scipy.optimize)
• Callback functions for monitoring optimization
• Classical pre/post-processing capabilities

9. Extensibility

• Custom gate definitions
• Plugin architecture for new backends
• Custom transpiler passes
• Open source (MIT licensed)

10. Visualization and Analysis

• Circuit diagrams in multiple formats
• Measurement histograms and state plots
• Bloch sphere visualization
• Publication-quality output

Resources and documentation:

• Qiskit Documentation
• Qiskit Tutorials
• Qiskit GitHub Repository

Last Updated: April 2026 Qiskit Version: 0.44.0+ Difficulty Level: Beginner to Intermediate (requires basic quantum computing knowledge)