Quantum supremacy refers to the point where a quantum computer outperforms the most powerful classical supercomputer in a specific task. In 2019, Google claimed to achieve quantum supremacy with its Sycamore processor, solving a complex problem in 200 seconds that would take classical supercomputers thousands of years.

However, quantum supremacy does not mean full practical use of quantum computers yet. The biggest challenge is quantum error correction (QEC), as quantum states are extremely sensitive to noise and decoherence. The development of fault-tolerant quantum computers with logical qubits (error-corrected qubits) will be essential for realizing real-world applications such as drug discovery, financial modeling, and AI acceleration.

By 2025+, researchers are expected to develop quantum advantage, where quantum systems consistently outperform classical systems in practical applications beyond theoretical demonstrations.