Quantum computing will move business, science, and government forward in unprecedented ways by solving problems that are too complex for today’s computational systems.
~ D-Wave Systems
What is Quantum Computers?
Quantum Computers are a class of new generation computers that works on the basis of Quantum Mechanic concepts such as Superposition and entanglement. These computers are capable of computing operations that would take tens of thousands of years in a normal computer, in just a few minutes.
In 2019, Google released a video and an article that Google has achieved what they call a "Quantum Supremacy" which means that Google has created a Quantum Computer that outperformed worlds best supercomputers. They claimed that their Quantum Computer was able to solve a problem in less than 4 minutes that would take more than 10,000 years in a supercomputer.
Why Quantum Computers? Why not better normal computers?
A computer is just an electronic machine that takes some sequence of electric pulses as input and produces some other sequence of electric pulses as output. These pulses are represented as Binary digITS (0 or 1) also known as bits.
These bits are just switches turning on and off, 1 means a switch is turned on and 0 means that switch is turned off. Also, these switches are built with an electric component called Transistors.
For the past seven decades, scientists are trying to make these transistors smaller and smaller. In 1965, Co. Founder of Intel, Gordon Moore noticed that the amount of transistors in a computer chip nearly doubles every 18 months. This statement of Moore later became Moore's law as we all know it. Scientists were able to abide by this law by making the size of transistors smaller and smaller and adding more and more transistors inside a CPU of almost the same size. There are almost 1.7 billion transistors packed inside an Intel i7 CPU.
This was all good until a few years ago when transistors became so small (less than 5nm) that quantum mechanics became an issue. To understand this, you need to understand how transistors work. And since it is beyond the scope of this post, you can see this 8 min video by youtube channel Real Engineering. I recommend watching this video if you don't know how a transistor works before continuing this post.
The reason transistors won't work in sub-atomic space is because of a quantum mechanical concept called Quantum Tunneling.
The most "Explain Like I'm 5" version of quantum tunnelling is a metaphor by the youtube channel MinutePhysics. Imagine that you roll a ball down a hill there is a 100% chance that the ball will be at the valley and not at a valley between some other hill.
But imagine that the ball is an electron and you roll it down a hill, then there is a 99.9999999% chance that the electron will be at the valley of that hill and 0.00000001% chance that the electron is at the valley of some other hill or maybe inside the hill.
So in transistors, when depletion layers are very thin, the electrons can sometimes jump to the other side of the depletion layer and complete the circuit. The thinner the depletion layer more the probability of occurrence of Quantum Tunneling.
Heads up, I'll mention some principles and equations in physics and bold them so that you can look them up if you want.
Heisenberg's Uncertainty Principle says that we can't measure both the position and velocity of a particle at the same time. Not because we aren't technologically advanced but because unlike normal objects like a ball, quantum particles are probabilistic. This means that we can tell a ball is on the table with a 100% probability without even looking at it but in case of an electron, we can only tell that the electron might be in this position with some probability that is not 100%. The probability of position of any quantum particle is given by a Wave Function if you majored in physics then you might have seen this equation but most likely got scared, like me.
This function provides the probability of a particle as a wave, this is whole wave-particle duality thing everyone talks about and points to Double Slit Experiment.
Now as any wave, when it collides with a barrier, reflects. But this does not explain quantum tunnelling. Whenever a wave gets reflected from a barrier there is a quickly decaying wave that goes through the barrier, this is called an Evanescent Wave or Frustrated Total Internal Reflection. If the barrier is thin enough this wave will go beyond the barrier creating a tiny possibility of the particle being on the other side of the barrier. Also known as Quantum Tunneling. I'll embed this video from the youtube channel The Action Lab as an experiment that you can do at home to see Quantum Tunneling in action.
Now back to the topic, because of this reason, when the transistors get smaller the depletion layers (the barrier that's stopping the electrons from flowing) and as we all know by now, the thinner the barrier, larger is the effect of quantum tunnelling.
Potential Applications of Quantum Computers
Quantum Computers work in the quantum space where the reality is stranger than fiction. Using a Quantum Computer,
- We can potentially break and redesign our current encryption system, it is possible for a quantum computer to break your bank's security in just 2 or 3 minutes as compared to 10000+ years of computation using a regular computer.
- Develop new drugs and cure to deadly diseases by simulating protein molecules, this is because a quantum computer works on the same principles that it is trying to simulate.
- Zero-latency information transfer will be possible with a quantum computer making your internet infinitely faster.
These are some examples of applications of quantum computers and there are many more to be discovered.
My plans with Quantum Computer?
Through this series of blogs, I will share my experience and research about Quantum Computing and try to contribute my part on the development of quantum computing and quantum softwares.
Follow my blog if you want to read future posts on this topic.