With so much happening in the technology domain, it becomes very difficult to keep up with it. With the introduction of blockchain, chatbots, LLMs and other complex topics, we are no longer at the privilege of getting to know the field. We are generally caught up in the race of being the first one to master the topic or build something out of it. However, this makes us keep on switching from one topic to another and we end up being a master of none.
To pursue a field it becomes essential to resonate with the topic or the phenomenon it is trying to understand. After all it’s a long term commitment. That being said, it becomes essential to understand the origin of the technology before looking into applications of it. It helps you connect with the cause and lead you to a greater path. This not only helps you answer question like – origin of the technology, basic nature, what are we trying to solve or what evolution in the field looks like, however it brings one closer to the essence of technology. It will tell you why this is a top worth learning about (if you find it fascinating), is it worth putting efforts into to or most importantly “Is this for me?”.
Quantum computing is a complex topic and diving straight into the application makes it more complicated. However, looking at the origin of it takes you much more closer to the cause. This is where the “Double Slit Experiment” comes into picture. Its an example of what made physicists so interested into this topic and how mesmerising it could be to visualise what the possibilities are and we do not know to what extend the unknowns exist in the universe that are not yet pinned by out laws or axioms or mathematics.
History of the Double Slit Experiment
The debate over whether light is a particle or wave goes back centuries. Double Slit experiment was first conducted by Thomas Young in 1801 at The Royal Institute. Yes, it goes back ~40 years. The basic idea was based on the fact that if two sounds interact with each other they create a beat and similar can be true for optical equivalents as well. While pondering over Newton’s corpuscular theory, he also observed that the air and water interaction sometimes leads to light reflection and at some places its refracted. For answering a few questions like this, he came up with the double slit experiment.
Let’s look at what the experiment is all about. I will be taking you one by one and help understand the logic of it and why it matters or an essential discovery for quantum mechanics.
Double Slit Experiment
The basic idea behind double slit experiment is that electrons are passed thought a board that has two slits in it (as depicted in the coverage of the story) and observe the corresponding results on the screen that is being the board. Let’s understand how it works for balls 🥎 to start with.
Round 1 (Balls)
1 slit
A very simple depiction where first we start with small balls being thrown from just one slit. and this is how the output should look like:
Now, this looks alright that some of the balls will bounce of the screen and the ones that pass will form a structure like that on the wall.
2 Slits
Similarly here now as there are two slits, there will be two lines on the wall
Round 2 (light)
Let’s repeat the experiment with a monochrome light and check how the pattern will look like when its two slits.
The result shows a wave length of light where the light from two slits interacts and at someplace it cancels it effect (dark patches on wall) and other it combines thereby enhancing the light and you should be able to see that on the screen itself. However, the quantum physics has a letdown from there however lets look at how electrons behave and this will be a step towards understanding basics of quantum physics and how the qubits come into picture.
Round 3 (electrons)
It was quite understandable how light behaves in this manner however, while doing this experiment with electron says this:
hypothesis: It behaves like small balls and will leave two lines similar to slit on the wall
Above results are totally astounding, instead of behaving like small balls and creating two lines on the wall it depicts a light like behaviour. but that doesn’t seem logical. If the electron is thrown though the slits either they go though slit 1 or slit 2, it should not be behaving like that.
Adding an observer
To make sense out of this, it was decided that the electrons will be observed to check how this pattern is being created what electron goes through what slit and check if how they refract. Therefore, an observer was added need the split screen to observe this and the results were as follows:
This is another mystery, that if the electrons are observed they behave differently. This is where the concept of qubit can be related to. The moment one observes the states, they are irreversible. It’s like Schrödinger’s cat experiment, once you open the box the output is irreversible.
Conclusion
I do not want to add any conclusions here I want to keep your thoughts fuelling. This is a phenomenon that can not be concluded easily. However, I would like to leave you with this famous quote for quantum mechanics:
If quantum mechanics has not profoundly shocked you, you have not understood it yet – Niels Bohr
Please feel free to contact if you would like to talk more about it.
References
- May 1801: Thomas Young and the Nature of Light: https://www.aps.org/archives/publications/apsnews/200805/physicshistory.cfm
