While it is true that quantum computers are actively being developed and used by companies like Google, IBM, and others, there are still some people who express skepticism or claim that quantum computers don't exist. The reasons behind such skepticism can vary, but here are a few common arguments:
Misunderstanding or lack of awareness: Some individuals may not be familiar with the current state of quantum computing research and development. They might not be aware of the progress made in building quantum computers or the successful demonstrations of quantum algorithms. This lack of information can lead to doubts or claims that quantum computers are purely hypothetical.
High technical complexity: Quantum computing is an exceptionally complex field, and the concepts and principles involved can be difficult to grasp fully. The underlying physics of quantum mechanics, superposition, entanglement, and quantum gates are counterintuitive and can challenge one's understanding of conventional computing. Some skeptics may find it hard to accept the reality of quantum computers due to the abstract nature of these concepts.
Limited availability and practicality: While quantum computers do exist, their practical applications are currently limited, and their availability is restricted. Quantum computers are still in the early stages of development, and the number of qubits (quantum bits) and their stability are major challenges. As a result, most quantum computers are not yet capable of solving complex real-world problems that cannot be efficiently tackled by classical computers. This limited practicality can lead some individuals to question their existence.
Confusion between general-purpose and specific-purpose quantum computers: Currently, most commercially available quantum computers are noisy intermediate-scale quantum (NISQ) devices. These devices have a limited number of qubits and are more suitable for specific types of quantum computations rather than general-purpose computing. Some skeptics may mistakenly assume that if a general-purpose quantum computer doesn't exist, then quantum computers as a whole are non-existent.
It's important to note that the skepticism surrounding quantum computers does not reflect the consensus among scientists, researchers, and experts in the field. Quantum computing is an active area of research, and while challenges remain, significant progress has been made in building and utilizing quantum computers for specific applications.