What Quantum Means

First hundred years of quantum

The field of quantum science was born in 1900 with Max Planck’s hypothesis that electromagnetic radiation, which encompasses light and radio waves, comes in discrete quanta, now known as photons. The resulting quantum theory, developed over the following 30 years, not only solved the problem that Planck was addressing, the color of light emitted by a hot object, but many other foundational puzzles such as the stability and discrete levels of atoms and the reason some materials conduct electricity while others are insulators.

The development of such quantum ideas had profound societal impact beyond just solving curiosity driven questions. Quantum concepts provide the fundamental basis for describing the energy bands of the semiconductors used for microelectronics, lasers, and lighting, for magnetic resonance imaging used in health care, and for the atomic clocks essential to the global positioning system used for navigation.

Next hundred years of quantum

Popular descriptions of quantum theory focus on the counterintuitive aspects, namely coherent superposition, i.e., whether Schrödinger’s cat is dead or alive, and entanglement, the fact that the measurement on one particle can determine the state of another that is far away. Actually, neither of these have been exploited in the technologies mentioned above. However, in the 1980s and 90s, it was realized that coherence and entanglement could be resources to develop entirely new technologies. The first of these was quantum computing, but now include quantum communications and quantum sensing. Efforts to exploit coherence and entanglement for applications is often known as “Quantum 2.0” to distinguish from the more “mundane” application of quantum concepts to describe single particles or semiconductors such as silicon. A key concept in Quantum 2.0 is the “qubit” which is the quantum version of the “bit” used in classical computer technology.

Quantum science and technology as national priority

The recent advances have put technology on the cusp of a revolution based on incorporating quantum superposition and entanglement as key functional resources. The NSF Quantum Leap program, started in 2017, and the passage in 2018 of the $1.2B National
Quantum Initiative
, demonstrate that the importance of quantum technologies has been recognized and is having an impact on national science policy. Both of these programs have provided significant funding opportunities for academic institutions to establish large multi-PI
research centers. Quantum also figures prominently in the Innovation and Competition Act, recently passed by the Senate, demonstrating that quantum is a long-term priority and a multi- billion dollar funding opportunity.