Quantum cryptography and cybersecurity
Nicolas Richard Castro
Traditional computers are reaching their physical limitations, as transistors, the fundamental building blocks of all computers, will not be able to decrease in size much beyond their current 10 – 20 nanometre width. Decreasing in size creates the ability to fit more transistors on a chip, allowing the computers to operate faster and more energy efficiently each year. However, despite claims that Moore’s law is still valid, 1 the end is undeniably in sight, 2 because it is unrealistic to expect companies to mass-produce transistors much smaller. For example, Intel is producing microscopic 14nm silicon transistors, and the atomic size of silicon is 0.2 nm 3 meaning that these transistors are just 70 silicon atoms wide. Aside frommanufacturing limitations, the reason why silicon transistors cannot get much smaller is due to a phenomenon called quantum tunnelling 4 where electrons can transfer themselves to the other side of a barrier if it is only a few atoms thick. With an industry market value of over $300bn 5 despite these obstacles ahead, there is a constant flow of new ideas insisting these transistors can be made even smaller, such as by using molybdenum disulphide and carbon nanotubes instead of silicon, 6 or using technologies such as IBM’s ‘ silicon glue ’ and Invensas’ chip -stacking process to squeeze more transistors onto a chip. After reading articles on these technologies, I understand that not only are they years away; they are also short-term supplements which will improve the speed of computers by fractions. Although being very advanced and innovative methods, what interests me the most is when speeds improve exponentially. In terms of speed, efficiency and innovation power, every direction points towards the quantum computer. However, without the adequate security measures in place, quantum computers could become more of a danger to the world rather than an advantage. A quantum computer is a computer that harnesses the quantum properties of subatomic particles to store and process information. Like the bit in traditional computers, the simplest unit of information in a quantum computer is the qubit which can also be set to either on or off. However, the qubit is any two-level system (for example, the spin in a magnetic field or a single photon) which uses quantum properties enabling it to exist in any superposition of the two independent states. This means that each qubit can be a proportion of both states such as a photon which has 70% vertical polarization and 30% horizontal polarization. When it is tested, however, by passing the photon through a filter, the photon will become either completely vertically or horizontally polarized, and the qubit will only be one of the two possible values. Comparing eight bits to eight qubits, we can see the revolutionary power a quantum computer has the potential to hold. Eight bits allow 2 8 different possible combinations to be chosen from to be used at one time. On the contrary, due to superposition, eight qubits allow all 2 8 different combinations to be used all at the same time. Therefore, each new qubit that is added allows the different possible combinations that can be used at once to grow exponentially. With 20 qubits the
1 Shein 2020. 2 Rotman 2020. 3 Anthony 2020. 4 Seabaugh 2013. 5 Statista 2020. 6 Thompson 2016.
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