Quantum Superposition (SIMPLIFIED)
Now, hear me out. There is a saying that goes, the more you learn about Quantum Mechanics, the more you realize you do not understand it. This is true especially when you start venturing into wave-particle duality and Quantum entanglement, it’s a mess. For the record, I am by no means a Quantum physicist or an expert in the field, I have just been very curious about the topic since 2016 and I have been doing research, reading papers and videos, and listening to people in the field talk about the topic and I just wowed every time especially the Applications in Quantum Computing and Simulation of complex quantum Systems.
Of course, as a person in IT, my interest in Quantum Mechanics relates to how we can apply it in computation. Before we do that, let us cover a little bit about classical computers and their fundamental building block which is the bit system. What is a bit? They say a bit is a 0 or a 1. It’s a rather simple explanation that is commonly used that I find might be rather too simple thereby making it harder for newbies to understand. This is how I’d describe it.
Classical computers use electrical circuits for computation, and at their core, electrical circuits work by switching(ON or OFF). By combining the switching into different combinations(Logic gates ), the computer can generate complex circuitry to solve problems. Therefore 0 and 1 are notations that are used to represent the two fundamental switching states, these could be Low or High-voltage represented by 0 and 1 respectively. This is the reason computers can only understand binary. So basically binary is a discrete system trying to mimic an analog system, and when has that ever been efficient?
You can see that from this graph, a discrete signal trying to simulate an analog signal(sine wave) is a little problematic, there is information loss. This is exactly why music recording studios still use records to store original music recordings.
Now Quantum Computing was introduced as a completely new way to tackle computation. Quantum computing and Classical computing are as different as Bulb is to a candle, this means that Quantum Computing aims to exponentially improve computation from where classical computing has failed, but takes a fundamentally different approach.
Quantum Computers use Qubit for computation as opposed to bits on classical computers. A qubit can be anything from an electron or proton, photon, or even a neutron. You can already tell that the Qubit which is the fundamental computing system for a Quantum computer already follows the laws of quantum mechanics and that’s what makes it special. While bits can only exist in two states, one at any given time? A Qubit exists in superposition. This means that it exists in a spectrum from 0 to 1 until such a time that it will be observed.
Usually when a Quantum system is observed, it collapses back into one of two states, a 0 or a 1. The 0 and 1 in a Quantum computer can denote a non-excited state and an excited state respectively.
This means that quantum computers can be used to simulate quantum systems with near great accuracy as long as all other factors are dealt with correctly e.g. interference
Okay now that we have explained superposition in a way that pleases the experts😂, let me now explain it to the average Joe😂 and for this, I have a great analogy. Okay, here we go.
Assume you are a very naughty kid and you live at home with your parents and your little brother. So let’s say your mother is very strict about homework and always wants you to shower immediately after you get home and then immediately start doing your homework. Meanwhile, your evil little brother finds out your little secret and threatens to tell your mom unless you do his homework for him immediately all the while, you just want to play some Fortnite 😂😂. So basically, your mom and brother keep budging into your room to check whether you’re doing your homework or in the case of your brother, his homework. So, what do you do in this case? Any suggestions?
What you would do is sit in front of your computer with both your homework and your little brothers’ homework and then play Fortnite while being careful enough to react in case either your mom or brother budges into your room, at this point, depending on who budges in, you do what pleases them. If your mother comes in, you quit the game immediately and pretend to be doing your own homework and if it’s your little brother, you would pretend to be doing his. You basically get to enjoy your game the entire time and decide on what homework to do at that moment the door is opened. Now let’s transfer this to Superposition.
A Qubit also exists in a spectrum(You playing video games) up until it is observed (your door is opened), then it will collapse into either a zero or a one(Doing your own homework or your brother’s homework). We know that the homework you choose to pretend to do will completely depend on who between your brother and mother budges in at that particular point in time. This is the same for a quantum system. The mere act of observing it changes its state.
In order to improve the accuracy of a quantum computing system, we introduce interference(constructive interference) which pushes the system probability of the qubit so that the right answer is highly likely and the wrong answer is unlikely.
Superposition can also be analogized by live betting on a football outcome. With livebetting you can watch the game and at any time of the game bet on which team to win based on observation and analysis of the ongoing game. You can pick the team that has been playing better for 65 minutes out of the complete 90 minutes of the game, this gives you a better probability of winning than having to bet on what team to win before the game starts. That is how superposition gives Quantum computers an advantage over classical computers.
