Quantum is a branch of physics that studies the properties of atoms. These properties are “weird”. For examples, an atom can be in many places at the same time or two distant atoms can sense what happens to one another without sending any signals. We have experienced quantum technology in everyday life, for example, computers, LED, solar cells, lasers, NMR, etc. However, these technologies only use partial properties of quantum mechanics and are called quantum technology 1.0. In quantum technology 2.0, individual atoms are manipulated to harnesses the full potential of quantum mechanics. Applications include
Within the last two decades, quantum technologies have made tremendous progress, moving from Nobel Prize award-winning experiments on quantum physics into a cross-disciplinary field of applied research. International Investment of more than 30 billion US dollars has been raised by governments and private companies such as Google, IBM, Intel, Microsoft, Alibaba, Huawei, Airbus, and many more.
A quantum (plural: quanta) is the minimum amount of any physical entity involved in a physical process. The word is used to describe a smallest and undivided unit of the magnitude of a physical property. An example is the energy of light which can take on only discrete values and can be only equal to integer multiples of one quantum (photon). This is considered as one of the weird properties of nature, of which the 400-year-old classical treatment of nature cannot explain.
Quantum mechanics is the field of science developed to explain exotic properties of nature that the conventional classical mechanics failed to describe. Quantum properties, such as, discretization of energies, small but finite undividable scale (such as the Planck constant), wave-particle duality, and many other strange properties of quantum states (quantum superposition (where two particles can be at two different locations at the same time) quantum entanglement (where particles can be highly correlated at extremely far distances), etc), have only been explored in the past century. The theory has included the development of condensed matter theory (explaining states of bulk materials) and optical field. However, there is still an extensive amount of knowledge that is yet to be explored and exploited for new technology.
In order to see the importance of quantum theory, we need to first see how our knowledge has been influenced so much from the old classical treatment of nature. We all learn and observe things, expecting that nature has definite values or definite properties. As examples, we all believe that a car should have a definite location in space and moving with a definite velocity, that a wave should have properties quite different from a particle, and that the moon should still be there somewhere around the earth even if we are not looking at it.
However, from what Quantum theory seems to tell us, it is that that definiteness of properties is no longer possible in the quantum regime such as in the atomic scale or at really low temperatures. Quantum theory says that a “car” made from a few electrons will not have definite positions or velocities until they are measured, a photon (a smallest indivisible unit of energy of light) has both particle properties and wave properties, and that a quantum particle might not be at the place you found it before its measurement.
In the past hundred years, there are immensely new theories developed from the new understanding of nature using quantum mechanics. The theory has been so successful that it can predict values to such a small precision with great accuracy. We understand better how atoms behave and can now able to explain the properties of different materials on earth using Quantum mechanics. Quantum theory, as a fundamental theory in physics, is the most promising candidate that can potentially change our way of understanding the world. Our current technologies, such as the electronic devices, have already exploited the quantum properties to some extent. Quantum theory has been so powerful that we (almost all of us) have technologies built from quantum theory in our hands (such as smartphones and tablets). Though we mostly did not realize that behind the fact that its powerful theory, the quantum weirdness properties listed above have not yet been brought to their full potential, and only recently started to be explored.