Understanding Schroedinger's Cat and Intro to Quantum Computing

Quantum Physics/Mechanics has been around for a few decades but Quantum computing (QC) has recently emerged as a breakthrough way of computing, with Tech giants fighting for Quantum Supremacy.

You would have heard claims that QC is exponentially faster than even the fastest supercomputers in the world today. So, what is the Science behind Quantum? Let us take a step back and start from where it begins...

I first got curious about Quantum physics when I learnt about a cat that could be either Dead or Alive or Both at the same time. She is the famed Schroedinger's Cat. I have pasted a link to that video in the references section below.

Simply put, Imagine a Cat that is kept inside a box with a radioactive substance. Radioactive exposure can kill the cat. However, the decay rate of radioactive atoms cannot be predicted.

Now, if you close the box, the cat's status can be described as both dead and alive. I know conventional thinking would say Either dead Or alive..but this is where the spookiness behind Quantum theory arises. The cat is dead or alive only when you Observe it. Till such a time that the box is closed the poor Kitty is both dead and alive. (Note the verb 'Observe' - we will refer to it at an important point later)

So, this mind boggling concept of Two States at the SAME TIME is called as 'Superposition of states'. The superposition collapses to one definitive state once you observe it. This is the one of the basic foundations of quantum physics/mechanics. The word 'Quanta' comes from Latin as discrete or small units - units here being sub-atomic particles. Another experiment that helps understand Quantum theory better is the 'Dual Slit experiment'.

Now, I am no Physicist by any means. But one gets intrigued by the usefulness of Quantum theory in Computing. Not long after the Quantum theory was validated, Computer scientists extended the concept of Superposition or Parallelism to Processing Bits; and the 'QuBit' was born.

QuBit in contrast to a classical bit can hold both 0 and 1 values at the same time. It is this property that gives an exponential processing power to Quantum computers. Imagine a tree with several branches and a bird perched atop one. While one classical computer will search for the bird by sequentially looking to the end of each branch, a Quantum computer can traverse multiple branches at the same time and return the results faster.

A classical 2 bit computer can have 2^2 states (00,01,10,11) at a given time, a quantum computer can have all these states at the same time. You can have only one input at a time to a classical computer , to a quantum computer you can provide multiple inputs much like looking for that bird on each branch of the tree SIMULTANEOUSLY.

If you scale to n bits, a quantum computer can have 2^n states at a given point in time - resulting in exponential increases in processing speeds.

All this may seem dandy, however, creating a perfect Qubit is one of the biggest challenges today. It needs temperature nearing absolute Zero (-273 C/ -460 F) because at these extreme temperatures sub-atomic particles can be made to reach quantum states!

As much as computer scientists across the world are working hard to create quantum super computers, it is well known that commercial usage of a QC is still 5-10 years away. However, they are trying to establish Quantum Internet that can even operate with a single QuBit at its node.

We will explore Quantum internet and more quantum weirdness like Entanglement and Observer's Paradox in the next article.

Meanwhile, if you are puzzled, you are on the right track!! Quantum theory takes you from Confusion to Curiosity to some Clarity and back to Confusion!

References

1. Schroedinger's cat
2. Quantum Internet and Quantum Computers - How will they change the world?
3. Google AI Quantum

Note: The views reflected in this article are the views of the author and do not necessarily reflect the views of any company or organization