Practical Guide to Quantum Computing – Quantum Computing in Practice (Based on Materials from IBM Q) # 8

Abstract This practical guide introduces hands-on quantum computing, based on IBM Q learning resources. The exercises were completed by the author on April 28, 2024, using IBM Q cloud resources. The course provides a practical framework for understanding and experimenting with modern quantum computers, covering realistic use cases, circuit execution, and best practices for operating quantum processors with 100 or more qubits. Participants explore the concept of quantum usefulness, which refers to the practical utility of quantum computers in solving real-world problems, distinguishing it from quantum advantage, which is the point where quantum systems outperform classical computers on meaningful tasks. The course emphasizes that while classical computers remain highly powerful and adaptive, the evolving capabilities of quantum processors offer unique opportunities in computation that can complement classical methods. Hands-on exercises guide participants through practical aspects of designing and executing quantum circuits, running experiments on simulators and cloud-accessible quantum hardware, and interpreting results. This approach bridges theoretical knowledge with applied skills, enabling students and researchers to explore the current potential and limitations of quantum computing. The guide also contextualizes quantum computing within decades of classical computational development, highlighting how quantum devices may transform computational paradigms in fields such as optimization, chemistry, cryptography, and machine learning.