The failure of classical physics, also known as ‘Newtonian’ physics paved the way for quantum mechanics based on the wave particle duality, proposed by De-Broglie which explained the concepts like the photoelectric effect and black body radiation. The reason behind failure of Newtonian physics was that it did not consider the wave nature of the sub atomic particles. The infamous Young’s ‘Double Slit Experiment’ further proved experimentally the wave particle duality i.e the subatomic particles can behave both as wave and particle but cannot behave as both at the same time. In this experiment when electrons were made to passed through the slits and their interference pattern was observed just like proving its wave nature. Even when a single electron is passed, it produces the same pattern as it behaves like a wave. The electrons when travelling in space behave like waves but as soon as it is measured, it behaves as particles. This is the ‘Wave-Particle’ duality.
But why does this dual nature of particles important to us ? Well, this wave particle duality applies to everything and is the reason why quantum mechanics came into picture. It forced physicists to rethinks all the fundamentals of classical physics around us. So what does quantum mean? The word ‘quantum’ means ‘fixed amount of something’. As the classical physics were unable to explain the photo-electric effect, the reason was that in classical mechanics the electrons were pictured to be moving around different energy levels called orbits. The quantum mechanics explained that the electrons revolving can move from one orbit to the other only when it will either loose or gain a certain ‘fixed’ amount of energy. This is called ‘Quantization of energy’. The equation that led to this quantum field is known as ‘Planck’s law’ which explains that the electromagnetic energy takes the form of tiny discrete packets – ‘quanta’ which is considered as the smallest unit of energy.
Planck’s equation is stated as:
E = h x f
Where E = energy of photon, h = planck’s constant and f = frequency of light
Value of h = 6.6 × 10-34 joule-second
This also explained the phenomenon of black body radiation. Einstein used this plank’s equation to explain the photoelectric effect leading to the discovery of photons which explained that even light also have particle apart from having a wave nature. This wave particle duality of matter gave rise to another principle known as the ‘Heisenberg’s Uncertainty Principle’ which explains the uncertainty in measuring a particle – it is not possible to accurately predict both the position and momentum of an object simultaneously.
The Heisenberg’s uncertainty formula can be given as:
△X × △p ≥ h/4π
Since p = mv,
It can also be written as : △X × m△v ≥ h/4π (as mass of a body remains constant)
Where â–³X is error in measuring position & â–³p is error is measuring momentum
This is more significant in microscopic world rather than macroscopic world, the reason being the mass of subatomic particles are comparable to the value of planck’s constant h and also large objects have very small wave nature for us to observe it.
This uncertainty in measurement can be used as a tool in the technology to take the computations to a whole new level – To the world of ‘Quantum Computers’. The quantum computing is the integration of physics and computer science which have a high potential to revolutionize the current technology and bring to life phenomenon like ‘Quantum Teleportation’ and ‘Quantum Tunneling’ which was otherwise thought to be impossible before. To harness the powers of this futuristic technology, the laws of quantum mechanics are exploited using its properties – ‘Superposition’ and ‘Entanglement’.