What is Quantum Supremacy?

Quantum supremacy refers to the moment when a quantum computer can solve a problem that classical supercomputers cannot. While quantum computers are advancing, they haven’t yet reached a practical stage where they outperform supercomputers in real-world applications. The term was introduced by physicist John Preskill in 2012, and in 2019, Google claimed to have achieved quantum supremacy. However, many claims have been contested as classical algorithms have caught up. The focus is shifting towards achieving “quantum utility,” where quantum computers can solve practical problems faster than classical systems. Despite progress, fault-tolerant quantum computers are still years away.

Quantum supremacy refers to the point at which a quantum computer can solve a problem that is beyond the reach of the most powerful classical supercomputers. While quantum computers are advancing, they haven’t yet reached the stage where they can outperform supercomputers in a practical, widely applicable way.

The term was first coined in 2012 by physicist John Preskill and has become a major milestone for those developing large-scale quantum computers. In 2019, Google claimed to have achieved quantum supremacy by solving a specific problem with their quantum processor. However, some of these claims have been contested, as researchers have developed classical algorithms that could handle similar problems.

Efforts to demonstrate quantum supremacy have often focused on problems that do not have direct practical applications, raising questions about how soon quantum computers will become truly useful. While no clear roadmap exists to go from quantum supremacy to solving real-world problems, experts believe that reaching quantum supremacy is a crucial step toward more advanced quantum machines.

Quantum supremacy experiments have been based on problems designed to favor quantum computers, such as random sampling operations. These challenges exploit the unique properties of quantum mechanics like superposition, where quantum bits (qubits) can represent multiple states simultaneously, enabling quantum computers to process many calculations in parallel. However, the technology is still error-prone, and simulations of quantum experiments have sometimes been performed faster on classical systems by sacrificing accuracy.

While quantum supremacy remains an academic achievement, the real goal for many researchers is “quantum utility” — showing that quantum computers can solve practical problems faster than classical systems. This is seen as a more meaningful step forward, as fault-tolerant quantum computers capable of solving real-world issues are still years away. Quantum supremacy, however, serves as an important milestone on the path to this goal.