Quantum physics is a complex and specialized field of study that requires a strong mathematical background and an understanding of advanced physics concepts. While it is difficult to provide an exact number, it is safe to say that the number of people who have a deep understanding of quantum physics is relatively small.
At the academic level, there are researchers, professors, and graduate students specializing in quantum physics or related fields. These individuals typically possess a high level of expertise and knowledge in the subject. Additionally, there are physicists working in various industries and government research institutions who have a solid understanding of quantum physics.
On a broader scale, many physicists and students have some level of exposure to quantum physics during their undergraduate or graduate studies. They may have a basic understanding of key concepts and mathematical formalism, although their expertise might be more focused on other areas of physics.
Outside of the physics community, the understanding of quantum physics becomes less common. Quantum physics deals with phenomena that are often counterintuitive and not easily observable in everyday life, making it a challenging subject for the general public to grasp fully.
However, with the increasing interest in quantum technologies and popularization efforts by science communicators, more people are becoming familiar with basic concepts of quantum physics. While their understanding might be at a more introductory level, it is a positive trend that promotes the dissemination of scientific knowledge.
Overall, quantum physics is a specialized field, and while there are many who are familiar with its basic concepts, a deep understanding is limited to a relatively small number of experts in the field.