Quantum computers, are they here already? Will they replace classical computers three years 2019 was the year when the world was assured of the existence of quantum computers. In from now?
January 2019, IBM declared its first quantum computer that could work outside a lab setup. In October 2019, Google claimed to have achieved quantum supremacy. Google developed a quantum computer that could carry out a specific calculation in 3 min 20 seconds. According to Google’s estimate, a classical supercomputer would need 10000 years to carry out the same calculation.
Though rival companies disagree on this estimate, it would be unfair not to acknowledge Google’s effort in providing experimental evidence of quantum speed. It was a significant scientific achievement that proclaimed to the world of Google’s hardware and software capabilities, but was it really an unflawed attempt?
Physicists say that the experiment carried out by Google was a very limited one. Had they added more qubits into the system, it would have disintegrated. According to them, more than exhibiting the supremacy of quantum computing over classical computing, what is important is to develop a quantum computing that can run anything for any given time without breaking down. To understand why that is a challenging thing, let’s try and understand what qubits are.
What Are Qubits in Quantum Computing?
In classical computers, we have bits that are binary and can take a value of 0 or 1. But in quantum computers, we have what is known as quantum bits or qubits that can exist simultaneously as 0 and 1. This property, known as superposition, is what gives quantum computing its exceptional power.
But the problem with qubits is that they are very fragile. Even the slightest disturbances such as vibrations, temperature fluctuations, electromagnetic rays affect qubits and lead them to break down. This process is called decoherence. So functioning of qubits outside of a controlled laboratory setup is highly unreliable. But if it can be achieved, theoretically, it can run such complex algorithms that are beyond the scope of classical computers.
How Practical is Quantum Computing?
The decoherence property of qubits makes quantum computing susceptible to errors. Unlike in classical computing, where error correction of one bit can be done using adjacent bits, in quantum computing, it is not possible. Any trial for measuring a qubit cannot succeed as the slightest interaction will cause it to disintegrate from its superposition state to a single state.
However, this can be circumvented by entangling qubits and forming a joint state from their individual states. Then one qubit can be measured from a pair of entangled qubits. So by constructing a large grid of entangled qubits, it is possible to detect and correct more quantum computing errors.
So quantum computers need a sophisticated, high-precision setup with temperature maintenance and complete isolation. Further, to solve practical computational problems, quantum computers would need 1000 to 100,000 qubits. And to maintain error correction, each logical qubit will need to be represented by 1000 to 100,000 physical qubits. This will amount to a few million qubits, making it very complex from the quantum mechanics perspective. And at present, experiments are being carried out on quantum computers with less than 100 qubits.
Recent Attempts in Quantum Computing
In August 2020, a University of Chicago researched a method to perform quantum computing that does not involve circuits. Their approach was to trick quantum particles into ignoring background disturbances, such as vibrations and temperature fluctuations, which cause them to disintegrate. They claim to have achieved successful results in a limited experiment setup.
Another technique called Quantum annealing is used by some commercial organizations such as D-Wave. It is also error-prone and effective only for specific algorithms. However, this approach has been successful to some extent. Volkswagen used this technique to route buses avoiding traffic jams and has declared their experiment to be a success even though it was performed in a controlled setup.
What Are the Applications of Quantum Computing?
The speed of quantum computers enables them to imitate quantum systems, leading to a detailed study of atoms, molecules, and their interaction. This can help in a significant breakthrough in several fields. In healthcare, it can help to discover new AI methods and pharmaceutical drugs. It can also play a great role in enhancing cybersecurity, weather forecasts, traffic control, etc. In the field of space also, quantum computing can be used to conduct significant research about black holes and dark matters.
Major tech companies such as Google, Microsoft, IBM, and Intel are investing tremendously in quantum computing. Investors are pouring money into this field to fasten the pace of development.
The Reality of a Quantum Future
All the research in quantum computing is very real. But the thing is, it isn’t ready to solve real-world problems yet. Quantum computing is still in the simulation phase. There are a lot of challenges to be solved, a lot of refinement to be done. But significant studies are going on this revolutionary technology. If we look at the breakthroughs made in the last few years, we can say that quantum computing would be a reality in the not too distant future.
It might not take over the classical computing infrastructure, but what it might do is work in sync with classical computers to achieve the unthinkable.