Why Quantum Computing is here to Stay ?
This article is an effort to explore the new world of quantum computing, expand on it’s differences and how it is better from the current computing and understand the basic concepts involved in quantum computing based on my understanding from the readily available materials. Any suggestions for improvements are most welcome
Quantum Computing is the new buzz word in the world of science nowadays. The reason for this craze is simple, modern day computers are reaching their limit in terms of how fast they can solve a complex problem.
Modern day computers gain there processing power from the number of transistors present on a chip. The current latest 4th gen intel processor has 1.7 billion transistors and their goal is to reach 100 billion transistors by 2026.
However, a big hurdle in the path of this spectacular achievement is scaling or basically the size of transistors. The size is important as the processing power of chip is directly proportional to number of transistors on a chip.
The current size of transistors is 14nm scaling technology, but researches show that it can be reduced up to only 7nm in scaling technology. Any further reduction in size leads to a phenomenon called quantum tunneling, which basically causes the electrons to transfer between the gates, thereby causing information leak.
This restriction in the size of transistors limit the number of transistors that can be paced on a chip, thereby restricting the processing power. This has created a technological barrier which has forced the world to explore the field of quantum computing.
Current Computing vs Quantum Computing
So the current way of computing revolves around 0 and 1. Transistors are the most elementary part of the circuits. They behave like a switch which can block or open the way of information coming through. The state of 0 or 1 is determined by the positive or negative charge or the spin of the electrons.
These states are called bits. Combination of these are used to store and process complex information, in the form of logic gates and combination of logic gates form basic modules.
Now, basic unit of quantum computers are called qubits. A qubit is equivalent of a bit in modern day computers, with a primary difference being that a value of a qubit is not fixed to be 0 or 1 but a superposition of both the values. Meaning, the value can be of the form of a linear equation a*0+b*1. Thus the value at a given instance can be a probabilistic combination of both 0 and 1 where a, and b represent the probabilistic weight.
However, the values collapses to a definite state on being observed. These qubits are programmed with a complex set of conditions, which formulates the “question”, and these conditions then evolve following the rules of the quantum world — Schrödinger’s wave equation — to find the “answer”.
Another interesting property of qubits is “Entanglement”, which makes all these qubits behave as a single system and properties of other qubits can be changed by changing the properties of a single qubit.
A quantum gate takes in these superimposed inputs, manipulates it and produces another superposition as an output. A quantum computer, which is actually a combination of quantum gates, collapses this output into an actual sequence of 0’s and 1’s.
Here is a short video which explains this beautifully
Why is it better than modern day processors?
A bit in current computer can be in only one state at a given time. Imagine a combination of 4 bits. The total possible combinations for these bits is 16. However, this set of 4 bits can be in only one of those 16 possible states at a given time.
Superposition, however in quantum computing enables for all the 16 combinations to exist at once. This enables the parallel processing to happen at a bit level instead of the sequential processing which happens in current computers, thereby drastically increasing the processing power of a computer. Information requiring 3 billion transistors can be done by just 30 quantum bits and search operations can be performed in sqrt(n) time.
These put quantum computers in a unique position to solve highly complex problems which need to run exponential number of scenarios to find solution to a problem, but take a lot of time to be done on current computers. There use in solving problems in the field of protein folding and quantum simulations can lead to major scientific breakthroughs in drug discovery & research and in our understanding of the physical world.
Types of Quantum Computers and Current Development
There are 3 basic types of quantum computers, quantum annealers, analog quantum and universal quantum computers. Quantum annealers are build for specific purposes only. Most famous example of a quantum annealer is D-Wave2 , a highly specialized system build for solving optimization problems and which was bought by Google for $10 million. It is said to be around 3600 times faster than the fastest super computer present.
Analog computer contains between 50 to 100 qubits and are expected to carry a combination of tasks. The universal quantum computer is the most general and the most challenging to build. They contain approximately 100,000 qubits. IBMQ is a project by IBM to develop first commercially available quantum computer.
The diagram below shows the growth of entangled quantum bits with time thereby tracing the history of quantum computers.
Challenges in Quantum Computing
Though research in quantum computers is catching pace with Australia and Canada being the leaders in this research but we are still a good 10 years away at least from a basic universal quantum computer. One of the major challenges in quantum computing is to keep the qubits completely isolated, so they are only being controlled by the laws of quantum mechanics, and not influenced by any environmental factors. Any disturbance to the qubits will cause them to leave their state of superposition — also called as decoherence. If the qubits decohere, the computation will break down.
Another challenge is transferring information from the quantum processor to some sort of quantum memory system that can preserve the information so that we can then read the answer. Researchers are working on developing ‘non-demolition’ readouts — ways to read the output of a computation without breaking the computation.
Conclusion
Though quantum computing is definitely an answer to solving a number of complex problems but the field itself is in very nascent stages. Even programming these computers is a totally different ball game as it is to be done keeping Schrodingers equation in mind. Lack of a definite value of a qubit makes it extremely difficult to think logically and knowledge required to program a quantum computer is going to be much different than the current requirements.
Despite these challenges there have been some significant explorations in various fields with Quantum Computing. D-Wave2 has proved the idea of quantum computers being used in complex calculations and already the company is exploring the Quantum Machine Learning. There are all the signs of the dawn of the world of quantum computing, and when it will arrive it’s going to open a whole new world of unexplored ventures for us.
Here’s another great website in case you want to explore more
and a link to videos if you want to learn quantum computing in detail
