Quantum mechanics
The key is formed by only keeping the photons read by the correct beam splitter, forming a sequence of bits. The reason why this is so different from regular cryptography is that in classical mechanics, particles' states aren't dependent on whether they have been observed or not as they are not probabilistic, but in quantum mechanics the act of observation has a direct effect on particles. When unobserved, a particle's behaviour such as spin and polarization is not definite but dictated by probability; however, when it is observed, it adopts a definite state. This means that if the photon is read before it is received it will change state and this change will cause an error as there is a difference between the photon's polarization and the beam splitter it went through, causing it to be discarded. This essentially makes the encryption unbreakable as this observer effect cannot be bypassed because it is coded in the particles as a law of quantum
Image from https://chem.libretexts.org/Courses/University_ of_California_Davis/UCD_Chem_107B%3A_Phys ical_Chemistry_for_Life_Scientists/Chapters/4% 3A_Quantum_Theory/4.09%3A_Quantum- Mechanical_Tunneling
mechanics. Now although this method does work and is truly unbreakable, it is not widely used across industries due to its limitations, particularly its speed (you are limited to sending one photon at a time through a fibre optic cable). Distance is also an issue as this method requires the state of the photons to not be changed and regular repeaters are unreliable for this. Progress is being made and companies such as Verizon are trialling quantum cryptography and, along with quantum computing, it could revolutionize security, but more time is needed to see it commonly used in industry.
Quantum computing
Quantum computers are computers which use principles of quantum mechanics such as superposition and entanglement to solve problems much faster than classical computers. Classical computers use bits which can either be a 0 or a 1 and in areas such as machine learning and optimization, this can reach its limits, requiring decades to solve certain problems. Quantum computers use qubits which also use 0s and 1s, but, due to the principle of superposition, it can be any combination of the two. Superposition also makes it able to read the quantum state in different ways, allowing the computer to run multiple computations at the same time rather than being limited to one at a time. Entanglement allows particles and therefore qubits to share information with each other, increasing efficiency and making it able to solve bigger problems. There are many problems currently plaguing the development of quantum computing, the most important of which is the delicacy of qubits. Slight changes in the environment such as vibrations or changes in temperature can cause them to change quantum state, effectively crashing the computer. This limitation can be overcome by keeping them extremely cold, just above 0 K, but this is not viable for wide use. Some examples of uses for it once it reaches a good enough level are simulating chemical reactions that are too complex for classical computers, which would assist drug and material research. It could solve very complex optimization problems, helping supply chain management and could help the development of AI through improving pattern recognition and data analysis.
121
Made with FlippingBook - PDF hosting