Quantum mechanics
Electronics
In the past two decades we have become increasingly more dependent on electronics. One of the major components of all electronics is the transistor: there are billions of them in every computer and phone
and their functionality is determined by quantum mechanics. A transistor is a semiconductor device used to amplify or switch electrical signals and power and is the backbone of the circuits that allow electronics to work. The main quantum idea behind transistors is quantum tunnelling. Quantum tunnelling is a phenomenon when a particle is able to penetrate through a potential energy barrier that is higher in energy than the particle’s kinetic energy. You can visualize an electron as a ball getting over a hill representing potential energy. In classical mechanics, the ball must have enough kinetic energy to get over the hill but in quantum mechanics the ball can simply pass through the hill, allowing a ball with a small amount of kinetic energy to bypass a large hill. This applies to transistors, where electrons can tunnel through an insulating barrier if it is thin enough, reducing the energy required for these operations to take place. This also provides a limit to how small you can make a transistor because if the internal barriers are thinner than a nanometre then electrons will tunnel through the barriers when the transistor is off.
Images from https://quantumxc.com/blog/quantum- cryptography-explained/
Atomic clocks
Our most accurate form of keeping time is the atomic clock which is based on the quantized nature of quantum mechanics. In an atomic clock, the caesium atom is exposed to radiation which is absorbed by its electrons, causing them to change energy level. Quantum mechanics says that these energy states
are exact so only radiation with energy exactly matching the difference between two energy levels can cause an electron to change levels. Because this transition is exact and remains constant it can be manipulated to measure time intervals by measuring the frequency of transitions which acts as a very accurate standard for frequency and therefore time. This has many applications apart from being the standard of time, such as its application in GPS. GPS works through the use of trilateration, where three satellites measure
Image from https://www.gps.gov/systems/gps/space/#:~:text=GP S%20satellites%20fly%20in%20medium,the%20Eart h%20twice%20a%20day
the distance from themselves to you, creating three spheres where you could possibly be, and the overlap being your location. The way it measures this distance is by firing a radio signal and measuring
119
Made with FlippingBook - PDF hosting