Computers that we know and love are all around us, they are fascinating. They manifest in our iphones, our tablets, our kindles, our desktops, our smart TVs, our laptops and last but not the least, our good old fashioned desktop computers. However, there is something common about all the computers I just mentioned. It is how they process information. You see, all these computers are based on classical computing, meaning that they process information in the language of 0 or 1 i.e., by using a classical bit.
There is a new way of encoding information where one uses not just 0 and 1 but also a superposition between them. A good analogy here is the following. A coin can either be heads or tails - this is like a classical bit (either 0 or 1). Now let us say we spin the coin, then it is neither heads nor tails, it can be thought of as being in a superpositon of head and tail--such is the case with a Quantum bit. Such superpositions can be attained in real physical systems of isolated atoms cooled down to freezing cold temperatures (down to miliKelvin), it this realm where one realizes a quantum bit. When we put many of these "Qubits" together, it becomes a Quantum computer. This is precisely what big companies like IBM and Google have achieved in building by using qubits made from superconductors. At present, the best quantum computer at IBM has 53 qubits while 72 qubits at Google.
A genuine question to pose -- what can quantum computers offer that classical computers can't? For starters, quantum computers provide means to factor really large numbers in an exponentially faster way than classical computers. But, how is that relevant to us? Well, the ability to factor large numbers forms the basis of modern cryptography. For example when you buy something online using your credit card, your card information is encoded as the multiplication of two large prime numbers. Only the seller is aware of the factorization. Since factorization is a hard problem to solve on classical computers no one can break in. However, if you had a good quantum computer and you knew the so-called Shor's Algorithm, then indeed you can break in. You could make so much money (fun but it would be illegal). Remarkably, how cool is that?
Are there other avenues where quantum computing can make an impact? Indeed there are, for example in the field of medicine most of the drug discovery is based on modeling the chemistry of molecules. At present, this modeling of molecules is done on classical computers and even with very few atoms the quantum states of a molecule are exponentially large. So large, that even the best supercomputers on the planet do not possess the memory. A quantum computer can circumvent this. It is more natural to represent the quantum states of a molecule in a quantum computer than in a classical computer. It also provides the means to map the exponentially large quantum states.
So what is the state of the art in the field of quantum computing? Who is leading the way? Let me answer these questions. At present there are many companies involved in the development of quantum computers and are funneling money into their research and development. This is because of the immense potential quantum computers have. At present, companies like IBM and Google are leading this field. Recently, Google announced that they have achieved "Quantum supremacy" in a research article published in Nature. The term "Quantum supremacy" was coined by Prof. John Preskill, a theoretical physicist at California Institute of Technology (Caltech) to describe a quantum algorithm which would solve a problem with a superpolynomial speed up compared to classical algorithm (few minutes vs thousands of years). However, this claim was refuted by IBM. Nevertheless, this has been a great achievement and is a step forward in the quest for the best quantum technology.
This all seems great and holds a promising future. What we need now is more people to get involved in this field and make contributions. Such efforts will take us ahead in the field, this is where you come in. So how can you get involved? Can you get hands on with a real quantum computer? Fortunately, the answer to this question is yes. IBM has made its quantum computer available for public use. This means you can write quantum algorithms yourself, code them and then run them on IBM's real quantum computers. The way to do this is through a Python package developed at IBM called Qiskit. The package has been designed to build quantum circuits on Python and then by requesting an access to IBM Q experience you can submit your quantum code to run on a real IBM quantum computer. How cool is that? You can tell your friends "Hey, last night I wrote a code and I ran it on a Quantum computer." and I am sure they will be amazed. If you read this, make sure you check out Qiskit.
Before, I end this article I would also like to break some myths about quantum computing. Quantum mechanics itself is a hard subject, it has been an everlasting mystery to human beings. Even though it has been the pride and joy of scientific community, the mystery it surrounds has given opportunity to many to make it more than what it is. So, let us take a moment to view some myths about quantum computers.
Quantum computers will forever replace classical computers: No, this is not going to happen. Quantum computers are great at solving certain classes of problems but would be useless for others. Our civilization will evolve by using a combination of the two.
What's the problem? just add more qubits: Certainly, we would like to add more qubits in order to realize quantum computers that can run Shor's algorithm of prime factorization (it needs around 100,000, we are at best at 72). However, the power of quantum computers is also its Achilles' heel. As you add more qubits, the system becomes very sensitive to even slightest perturbations of environment and looses its quantum nature (decoherence).
Quantum computers will revolutionize everything in next 20 years: This is far from reality. Although, we have made great strides with Google and IBM but we still need to do a lot of work on the engineering side for making quantum computers reliable (fault tolerance). We are at the stage of "vaccum tubes" and "transistors" of quantum computers. A long but exciting road ahead in the future.
Lastly, I would like to close by saying that one of the goals of this article is to introduce you to this new and wonderful way of computing. It is to inspire you into taking up the mantle in such fields. Making efforts in this field will bring a rewarding future to you. One must remember, every once in a while it is a curious kid who changes the course of future. Lead the way and the world will follow. Welcome to the field of quantum computing.
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