The development of "real" quantum computers is an active and rapidly evolving field of research. While there has been significant progress in recent years, building practical and scalable quantum computers still faces numerous challenges. The timeline for achieving a fully functional, fault-tolerant, and commercially viable quantum computer remains uncertain.
Here's a breakdown of the current state and some key milestones:
Quantum Bits (Qubits): Quantum computers use quantum bits, or qubits, as the fundamental units of information. Progress has been made in creating different types of qubits, including superconducting circuits, trapped ions, topological qubits, and more. Each qubit technology has its advantages and challenges, and researchers are actively working on improving their performance, coherence times, and error rates.
Quantum Supremacy: In 2019, Google claimed to have achieved quantum supremacy, demonstrating that their quantum computer could solve a specific problem faster than any classical computer. However, the problem solved was highly specialized and not applicable to most practical applications. Achieving quantum supremacy in a broader range of useful problems remains a goal for the field.
Quantum Error Correction: Quantum systems are susceptible to noise and errors due to interactions with the environment. Quantum error correction (QEC) techniques are being developed to address these errors and protect the integrity of quantum computations. QEC is a crucial step towards building reliable and scalable quantum computers, but it is still an area of active research.
Scalability and Fault-Tolerance: Building larger quantum systems with more qubits and achieving fault-tolerant quantum computation are significant challenges. Quantum computers require a sufficient number of qubits and reliable error correction to handle complex calculations effectively. Current quantum systems have a limited number of qubits (up to a few hundred) and suffer from noise and errors, making them challenging to scale up.
Practical Applications: While there are already algorithms, like Shor's algorithm for factorization, that could potentially provide quantum advantage, translating these algorithms into practical and useful applications is a complex task. Identifying and formulating problems that can benefit from quantum algorithms and demonstrating their advantage over classical methods is an ongoing research effort.
It's difficult to predict an exact timeline for when "real" quantum computers will be fully realized. However, the progress made so far and the level of investment and research in the field suggest that we are moving closer to practical quantum computers. Continued advancements in qubit technologies, error correction, and algorithm development will be instrumental in bringing us closer to the goal of achieving scalable and commercially viable quantum computing.