The great American physicist Richard Feynman once said, “If you think you understand quantum mechanics, you don’t understand quantum mechanics.” The nature of the subatomic and quantum world has confused even the greatest scientists and has proven to be fiendishly complicated. The premise of quantum mechanics is that particles do not have fixed qualities. Their characteristics like speed, location, and momentum cannot be known with precision. Only estimates can be drawn up. As confusing as it may seem, a subatomic particle can theoretically be in different places with different probabilities, which are determined by something known as the ‘wave function’.
Quantum computers fascinate scientists because of their potential applications. Normal computers operate using 0s and 1s. A switch can be on (1) or off (0) and information is transferred accordingly. This is what is meant by ‘bytes’ of data. The bit or byte is a measure of how much information is required to define a process. Quantum computers utilise the strange behaviour of subatomic particles to bypass certain limitations. Quantum computers use quantum bits, or ‘qubits’, as opposed to ordinary bits. While ordinary switches can be on or off, qubits are simultaneously on and off and assume one of the states when they are ‘observed’. The likelihood of being on or off is determined by a probability assigned to the qubit which is determined by the wave function of the qubit (mentioned earlier).
The wave function of a qubit. Source: ITIF
The precise mechanics of the system is not something which the average human mind can easily comprehend, but what this means is that quantum computers can be used to perform functions which did not seem possible before. Due to the nature of the qubits, quantum computers can transfer and process more information and data and can perform calculations and functions exponentially faster than a traditional processor. Quantum computers can be used to break secret codes which may take normal computers decades and even centuries to crack. Some scientists are actually worried that if quantum computers were to be developed on a larger scale and made accessible, the security of the Internet and of secret agencies would be under threat. On the flip side, quantum computers can also be used to enhance security by creating unbreakable keys which are needed to access information.
A quantum computer. Source: Daimler
It is extremely difficult to build even a basic quantum computer. There are hardware issues and quantum issues. A major obstacle in the development of quantum computers is the decoherence problem. This is when the qubits lose the information that they are supposed to carry because of undesirable interaction with the outside environment. They are fragile and a lot of precision is required to maintain the desired quantum states. For the near future at least, quantum computers pose no major threat to world security.
As recently as in March 2020, there was an accident in a laboratory that turned out to be a happy accident for scientists. The accident solved a problem that had had scientists scratching their heads for the last half-century. The discovery has made it easier to control individual atoms in quantum computing systems. Earlier, magnetic fields were used, but this was cumbersome because it is difficult to apply magnetic fields in very small spaces. Scientists can now use electric fields to control atoms. This is very important for the future of quantum computing and for the development of quantum computers.
This is not the first time breakthroughs have been made unintentionally in the field of physics, and it certainly won’t be the last. The field of quantum mechanics has too many unknowns and research is still in its early stages.
How quantum cryptography might work. Source: BBVA Openmind
By Aahan Tulshan