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An Introduction to Quantum Physics
Quantum Physics has an association with quantum mechanics. Quantum physics by definition is studying matter and energy at the most fundamental level. The aims of quantum physics are to uncover the properties and behaviours of the very building blocks of nature. While many quantum experiments examine very small objects, such as electrons and photons, quantum phenomena are all around us, acting on every scale.
It is important to note that quantum physics goes by other names: quantum mechanics; and quantum theory (Walker, Halliday and Resnick, 2014). For this article, I will call it quantum physics – mainly because it sounds cooler.
Although the world of the very small is remote from our five senses, it shapes our daily life experiences. Almost everything we touch and see owes its character to the subtle architecture of atoms and molecules, an architecture whose building code is quantum mechanics. When it comes to large-scale phenomena that depends directly on the details of atomic processes such as lasers, superconductors and solid-state electronics, the explicit use of quantum physics is essential (French and Taylor, 1978).
Areas of Quantum Physics
The development of quantum physics as a theory took nearly 30 years, starting in 1900 with Planck’s quantum hypothesis eventually leading to the theory of quantum mechanics of Schrodinger and Heisenberg. These are just some of the areas of this huge yet fascinating subject of quantum physics.
The Bohr Atom
In 1913, Niels Bohr proposed a theory for the hydrogen atom. This theory is called the Bohr model of the hydrogen atom. The theory explains the connection between the quantisation of photons and the quantised emission from atoms.
Wave Nature of Particles
The wave nature of matter is the idea that objects are composed of particles that move in waves. Atoms and molecules are made up of particles that are in a state of constant motion. These waves can be seen as vibrations or oscillations. This is what makes matter exist and it also gives it its properties.
The Photoelectric Effect
The photoelectric effect is an effect of electromagnetic radiation on metals show that electrons are emitted from the surface of a metal when electromagnetic radiation above a certain frequency is directed at the metal. The ejected electrons are called photoelectrons. In terms of their behaviour and their properties, photoelectrons are no different from other electrons.
In the late 1800s Hertz was experimenting with the transmission of radio waves and noticed that sparks were more readily produced between electrodes when they’re exposed to UV light.
If visible light or UV light is shone onto a clean metal surface, electrons can be ejected.
We have two models of light: the wave model of light; and the photon model of light. In the wave model of light, the energy delivered by the wave depends on the intensity (energy per second per unit area). More intense light waves have a larger amplitude and deliver energy at a greater rate. The energy arrives continuously and can build up over time.
In the photon model of light, light is made of many individual quanta called photons. Each photon has an energy given by 𝐸=ℎ𝑓. The intensity of the light is determined by the number of photons per second. Each photon can be absorbed by a single electron.
If you see a plus sign, it is a lattice of positively charged ions. If you see a minus sign, they are negatively charged ions. Metals can produce photoelectrons because they contain a ‘sea’ of delocalised electrons that require less work to remove than an electron bound into an atom. The blue circles in the diagram below is a sea of free/delocalised electrons.
There is a lot more but we need to get into quantum computing.
The Photoelectric Equation
The photoelectric equation is an equations concerning the rate of the electron emission from the surface is directly proportional to the frequency of the light and it is defined as the below equation: E = hf
hf = φ + EKmax
The breakdown is as follows:
· hf = energy of the photons of electromagnetic radiation
· φ = work function of the exposed material
· EKmax = maximum kinetic energy of the photoelectrons
Work function, φ
This is the minimum energy required for an electron to escape from the surface of a material
Conservation of energy
The energy of the photon is split between energy needed to liberate the electron (potential energy) and anything left over becomes kinetic energy of the electron.
Famous People in Quantum Physics
There are some famous people in the field of quantum physics. The Schrodinger Equation is a differential equation based on the wave function having to be a set of solutions. This equation was developed by its namesake Erwin Schrodinger in 1925. We can set up a Schrodinger equation for any given physical situation such as the electron in a hydrogen atom (Sears, Zemansky and Young, 1987). Heisenberg’s Uncertainty Principle is a principle whereby the position and momentum of a particle cannot be simultaneously measured with arbitrarily high precision.
An Introduction to Quantum Computing
I have only seen this topic feature in the Cambridge International exam board for A Level Computer Science. After all that quantum physics, now we get into what we have been waiting for – quantum computing. Quantum computing is an emerging technology that uses the laws of quantum physics as its basis instead of Boolean algebra, which has up until now been used on the computers we know (Dumas, 2019). Quantum computing combines quantum physics, computer science and information theory (Rieffel and Polak, 2011). Quantum computing is expected to be able to solve many problems that are too complex for traditional computer systems. It includes the problem of cracking the very long keys that provide the computational security of existing cryptographic systems. The basic idea of quantum computing became evident when Shor’s algorithm was published in 1994.
Advantages and Disadvantages
There are the following advantages:
· Data can be processed 1000 times faster than normal computers
· Best for simulation such as weather forecasting
· Medicine creation by detecting diseases and can create a formula for medicines
· Google searches can be refined
· High privacy – very good at cryptography
· Used in radar making by improving the accuracy of radar weapons
· Used in artificial intelligence (AI) by making decisions more precisely than normal computers
· Machine learning using less code and improve outcomes
There are the following disadvantages:
· Algorithm creation – a new algorithm is required for every type of computation
· The low temperature needed – requires a temperature of -460°C
· Not open for the public – high prices
· Internet security – potential to decrypt all codes on the Internet
There are other topics in relation to quantum computing but this article will be too long so will brush over these briefly. Topics include the Quantum Bit and Quantum Computer Architecture.
Quantum Cryptography
Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. In a cybersecurity context, it is a method of encryption that uses the naturally occurring properties of quantum mechanics to secure and transmit data in a way that cannot be hacked.
Digital communication systems rely on sophisticated encryption schemes to ensure that data is transmitted securely. The current schemes are not easily cracked. This is because existing schemes rely on hard problems. A hard problem is one that cannot be solved by today’s computer systems. This is not because there are no known solutions, but because it would take too long for a computer to produce the solution. Even supercomputers with thousands of CPU and GPU cores struggle to produce solutions to certain kinds of problems: the issue of cracking a modern encryption scheme is such a problem.
We can categorise these encryption schemes as ‘computationally secure’ although they could in theory be cracked, it takes too long for computers to crack the scheme. A good example is the integer factorisation problem. This problem, which is the basis of the gold-standard RSA encryption scheme, is that of determining the prime factors of a very large semiprime number. A semiprime is a number with exactly two prime factors. If you know the factors, it is very easy to produce the semiprime number; you just multiply the two factors together. However, finding the factors will take an awfully long time.
In 2020, a group of researchers in France managed to factor a 250-digit semiprime number (RSA-250) using approximately 2700 core-years of computing power (specifying the 2.1GHz Intel Xeon Gold 6130 CPUs as a reference). The next semiprime has not yet been factored. Researchers are confident that internet security is safe for the foreseeable future. The RSA-250 is a widely used encryption schemes, such as RSA and Diffie-Hellman, now recommend the use of a 2048-bit (617 decimal digits) key. As computers get more powerful, the degree of computational security afforded by these complex encryption schemes is diminished.
Shor’s Algorithm
Shor’s Algorithm is a quantum computer algorithm for finding the prime factors of an integer
Developed in 1994 by American mathematician Peter Shor. This was significant as it implies that public key cryptography might be easily broken, given a sufficiently large quantum computer.
At the heart of Shor’s algorithm is a superfast quantum Fourier transform. This can be carried out by a spectacularly efficient quantum circuit built out of 1-Qbit and 2-Qbit gates (Mermin, 2007).
Why Quantum Computing?
Quantum computing is now in the ascendancy for the following reasons:
The problems faced today are far more complicated than what advanced technology can address. Such concerns have high complexity, which means it would take centuries for today’s supercomputers to solve these problems. Some examples are modern cybersecurity problems, optimisation problems, stock profile management, problems related to aerospace, molecular study, and others.
Energy usage one such critical area. With the exponential growth of the global population, energy consumption increased. This has created a problem of ‘energy source optimisation’, which is difficult for current computers to tackle. Quantum computing can potentially solve such complex problems.
Commercial potential is immense. One example commercial benefit is in the agricultural sector. 50% of global food production depends on ammonia fertilizers. The ammonia is produced through a chemical process called the ‘Haber-Bosch process’, which requires high temperature and pressure. The physical constraints of the process are difficult to tackle as they cause considerable energy usage, which is one of the big problems.
Quantum computers can produce fertilizer at standard temperature and pressure with help of an enzyme called ‘nitrogenase’. This enzyme can handle a complicated catalytic procedures today’s computers cannot. Nitrogenase is mapped by traversing a path through 1000 atoms of carbon as part of an overall process. Quantum computers can generate molecular models of nitrogenase. Quantum computing can further design molecules similar to the enzyme and help produce low-cost and low-energy ammonia making ammonia-based fertilizers would be readily available and at affordable pricing.
Data handling is huge wherever our computing careers are. With the internet of everything coming to light, every Internet of Things (IoT) device, wearable, gadget, and sensor is interconnected to a computing network, thereby contributing to the generated data.
Modern computers and supercomputers are prone to errors when handling such a massive quantity of data, affecting performance. Computational tasks such as testing the effects of drugs at the molecular scale are complex for modern computers to manage. Quantum computers are better suited for such tasks as they can process significant volumes of data faster.
Reference List
Breithaupt, J. (2003) Physics Second Edition Basingstoke: Palgrave Macmillan
Dumas, J. D. (2019) Computer Architecture Fundamentals and Principles of Computer Design Second Edition Boca Raton: CRC Press
French, A. P. Taylor, E. F. (1978) An Introduction to Quantum Physics The M.I.T Introductory Physics Series Cheltenham: Stanley Thornes (Publishers) Ltd
Kanade, V. (2022) ‘What Is Quantum Computing? Working, Importance, and Uses’ Spice Works 12th July Available at: https://www.spiceworks.com/tech/artificial-intelligence/articles/what-is-quantum-computing/#_003 (Date Accessed: 23/08/2023)
Kaye, P. Laflamme, R. Mosca, M. (2007) An Introduction to Quantum Computing Oxford: Oxford University Press
Kirkby, L. A. (2011) Physics A Student Companion Banbury: Scion Publishing Limited
Lord, A. (2023) ‘Quantum computing of the near future: Overcoming society’s most profound challenges’ Innovation News Network 24th July Available at: https://www.innovationnewsnetwork.com/how-can-quantum-computing-of-the-near-future-overcome-challenges/35268/#:~:text=With%20every%20passing%20year%2C%20quantum,businesses%2C%20and%20the%20cybersecurity%20industry (Date Accessed: 23/08/2023)
Mermin, D. N. (2007) Quantum Computer Science An Introduction Cambridge: Cambridge University Press
Rehman, J. (2020) ‘Advantages and disadvantages of quantum computers’ IT Release Available at: https://www.itrelease.com/2020/10/advantages-and-disadvantages-of-quantum-computers/ (Date Accessed: 23/08/2023)
Rieffel, E. Polak, W. (2011) Quantum Computing A Gentle Introduction Massachusetts Institute of Technology
Walker, J. Halliday, D. Resnick, R. (2014) Principles of Physics Tenth Edition International Student Version New York: John Wiley & Sons Singapore Pte. Ltd
Sears, F. W. Zemansky, M. W. Young, H. D. (1987) University Physics Seventh Edition Addison-Wesley Publishing Company Ltd
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