Era of Quantum Supremacy is near

In a twist that even Google probably didn’t see coming, a draft of the paper describing the company’s quantum supremacy experiment leaked early when someone—possibly a research collaborator at the NASA Ames Research Center—uploaded the paper to the NASA Technical Reports Server. It might have sat there unnoticed before being hastily removed, if not for Google’s own search engine algorithm, which plucked the paper from its obscure server and emailed it to anyone who had signed up for Google Scholar alerts related to quantum computing. The paper was quickly removed from the website afterwards. Google and NASA both refused to comment on the same.

Google, as well as IBM, Microsoft, Intel, and other large tech companies and startups, have been working to build quantum computers, a new kind of computer based on an entirely different architecture than classical computers.

Why is it a Big Deal ?

For decades the processing power of our computers has been doubling approximately every two years as governed by the famous Moore’s Law. The growth in performance is because the size of transistors has been reducing , hence, the number of transistors that can fit on a processor chip has been increasing exponentially. But there is a limitation after which the size of transistors can’t be reduced further. At extremely small sizes laws of quantum physics and not newtonian physics govern motion of particles. Thus, the transistor will start exhibiting unexpected behaviour.

The Financial Times reports that they saw a Google publication claiming that the company’s quantum processor can perform a calculation “in three minutes and 20 seconds that would take today’s most advanced classical computer, known as Summit, approximately 10,000 years” — a demonstration of quantum supremacy.

Quantum supremacy is the potential ability of quantum computing devices to solve problems that classical computers practically cannot. The benefits of Google’s exemplary feat will be two fold. Firstly, it will provide the much needed escape from transistor size limitations. Secondly, it will provide us with unprecedented processing capabilities.

What is Quantum Computing ?

The idea of a classical computer is simple, and goes back to Alan Turing and the concept of a Turing machine. With information encoded into bits that is 0s and 1s, you can apply a series of operations (such as AND, OR, NOT ) to those bits to perform any arbitrary computations you like.

Instead of regular bits, which are always either 0 or 1, a quantum computer uses qubits, or the quantum analog of bits. A qubit isn’t in a determinate state, but rather lives in a superposition of 0s and 1s. Unlike regular bits, you can only predict the probability distribution of what the final state of a qubit will look like.

If you look at a system of more than one qubit, then the individual components aren’t generally independent of each other. Instead, they can be entangled. When you measure one of the qubits in an entangled system of two qubits, for example, then the outcome — whether you see a 0 or a 1 — immediately tells you what you will see when you measure the other qubit. Particles can be entangled even if they are separated in space, a fact that caused Einstein to call entanglement “spooky action at a distance”.

So let’s say you have an 8 bit system. We need to find how many bits are set to 1. While in a classical computer you will need to read all 8 bits, a quantum computer can get this information by reading the orientation of just the first bit. So the task which takes N (= 8 ) operations can be performed in a single operation in quantum computers !! The competitive advantage comes when N is very high and/or the operation needs to be performed multiple times. This is the reason why quantum computers can beat classical computers easily.

Applications

Some of the most promising fields that will be revolutionised by quantum computing are -

1. Cyber Security : The primary basis of security for encryption algorithms in use is the difficulty in factoring large numbers in feasible time. There, however, exist quantum algorithms for factoring of large numbers. In fact, the U.S. government is already taking steps to prepare for the future possibility of practical quantum computing breaking modern cryptography standards. The U.S. National Institute of Standards and Technology has been overseeing a process that challenges cryptography researchers to develop and test quantum-resistant algorithms that can continue to keep global communications secure.
2. Computational Chemistry : There are many problems in materials science that can achieve a huge payoff if we just find the right catalyst or process to develop a new material, or an existing material more efficiently. There is already a significant effort in using classical computers to simulate chemical interactions, but in many cases the problems become intractable for solving classically. So the original idea presented by Richard Feynman was why not use a quantum computer to simulate the quantum mechanical processes that occur.
3. Machine Learning : One of the most striking issues of machine learning is the time it takes for a model to compile. Current models sometimes need a few days to complete learning, even on the most powerful computers available. This results in delayed evaluation and analysis of said models. A few proposed models are only theoretical since we don’t have machines powerful enough to implement them right now. Quantum computers can help scientists break free of these shackles and revolutionise machine learning.

What this milestone represents ?

We probably haven’t even fully realised the possibilities that will open up with this kind of computational power. For a moment, compare the growth rate of civilisation before and after the advent of computers. Now imagine what a computer million times faster than the most powerful supercomputer in existence can do. The development and distribution of such stable quantum computers will push our civilisation forward at an unprecedented pace.

A surprising variety of global firms are working on Quantum computing applications. AT&T also recently said it’s working on quantum networking or the technology to link quantum computers. China is certainly looking into it from every aspect as well.

Towards the Future

Despite having put cyber security under serious threat, quantum computers will themselves present opportunities to develop advanced new encryption algorithms. And although the computer solved only a specific problem suited to its design and implementation, I am extremely excited about what this achievement holds for us in the future. The success of these early efforts will definitely lay a stronger foundation for the development of future quantum computers with more diverse applications and someday be able to perform tasks similar to today’s classical computers at a lightninglike speed.