Nat. Rev. Phys Editor's word Quantum physics is opening a new era ......

We celebrate the past and present of quantum physics and try to imagine its future.

The 1920s were a whirlwind of economic growth, intellectual emancipation, and rapid social and technological change. In physics, the Roaring Twenties marked a break with tradition, the birth of quantum mechanics. So far, the 2020s have been equally fast-paced and turbulent. On the centennial of the birth of matter waves, we ponder where the next 100 years of quantum mechanics will take us.

In 1923, Louis de Broglie published three short papers that set the stage for a series of breakthroughs. In the three years 1925-1928, the foundations of quantum mechanics had been laid: the exclusion principle, matrix mechanics, wave dynamics, the uncertainty principle and Paul Dirac's relativistic wave equation. Thus, by 1928, it seemed that the revolution was complete and the foundations of quantum mechanics had been laid.

-- Not so. It took decades to accept the concept of nonlocality that was initially proposed as evidence of the incompleteness of quantum mechanics. 1948 saw the introduction of the third formulation of quantum mechanics by Richard Feynman (in addition to the matrix mechanics of Werner Heisenberg, Max Born and Pascual Jourdan and Erwin Schrödinger's wave dynamics), which is called the path integral formulation.

Nevertheless, to this day, quantum mechanics is still not fully completed. Despite its extraordinary success as a mainstay theory in physics and related fields, and its impact on many technologies (whether lasers, semiconductors, or modern quantum technology), quantum mechanics has always had a mysterious aspect. This is due to the many conflicting interpretations of the theory (e.g., the Copenhagen interpretation, many-worlds interpretation, quantum Bayesian theory, and quantum Darwinism), resolved and unresolved paradoxes (e.g., the EPR paradox, Schrödinger's cat, or Wigner's friend), open questions (e.g., what is the nature of quantum measurement, how did it lead to the emergence of the classical world, and the still quantum theory of gravity that has not yet emerged), etc.

Today, physicists are in a good position to begin to demystify quantum mechanics. In terms of applications, we have state-of-the-art technology capable of extraordinary experiments, as discussed in two reviews: one on single-photon applications and one on quantum invisible transfer; and more resources than ever before: government funding for national quantum technology programs and intensive research by large companies and startups.

However, delivering quantum technology still requires fundamental research, so having more money and people should lead to progress. On the fundamental side, there are new directions to tackle the quantum measurement problem and the search for a quantum theory of gravity; however, we (Nat. Rev. Phys editorial board) believe that what will really make the difference is the new generation ready to join quantum scientific research.

Quantum mechanics was developed by young people. in 1923, bubbles, Heisenberg, Dirac and Jourdan were all in their 20s; de Broglie and Schrödinger, in their 30s, were late bloomers. In the spirit of the time, they came up with radically new ideas to explain phenomena that classical physics could not explain. Today, one starts much earlier: programs such as Qubit by Qubit or Quantum Schools for Young Students (QSYS) offer summer courses in quantum information and computing for high school and even younger students. Imagine these teenagers learning about superposition and entanglement, designing quantum circuits - they would be true "quantum natives.

Will they be inspired to pursue STEM careers, join the much-needed quantum workforce of the future, become the next generation of Paulis, Heisenberg, Dirac, or do something entirely different? More importantly, the inclusion of quantum physics in the high school curriculum and in the list of traditional disciplines means that it is becoming "classical".

Then, perhaps the new generation is ready: they will once again break with tradition and come up with one new "radical" theory after another in answering open questions about the foundations of quantum physics.

Reference links:

[1] https://www.nature.com/articles/s42254-023-00601-3

[2]https://www.nature.com/articles/s42254-023-00592-1

[3]https://uwaterloo.ca/institute-for-quantum-computing/qsys

[4]https://www.nature.com/articles/s42254-023-00600-4