Quantum Computing: Beyond The Limits of Traditional Computers

Quantum computing is the area of study focused on the development and developing computer technologies based on the quantum theory. The quantum theory is a theory which explains the nature and behaviour of energy and matter on a quantum (atomic and subatomic) level. Over time computers have become smaller and increased in power, the problem with this the process of improvement is it meets physical limits (Computer parts are approaching the size of an atom).

The computer is made up of the main memory, arithmetic unit and control unit; representing data, processing it, and control mechanisms. Additionally, computer chips contain modules, which contain logic gates, which contain transistors. A transistor is the simplest form of a data processor in a computer, it is essentially switch that can basically open or block the wave of information coming through. This information is made up of ‘bits’; digits 0 or 1. As the devices get smaller and smaller, quantum physics makes things complicated. Metaphorically, a transistor is kinda like an electric switch. In this metaphor, electricity would be represented by electrons moving from one place to another.

As transistors become the size of only a few atoms, there is the possibility electrons might just transfer themselves to the other side via quantum tunnelling. This is a challenge that can be solved with quantum physics. To solve this, scientists are trying to use quantum properties to their advantage by building quantum computers. Another aspect of quantum computation are its qubits. In a traditional computer, the smallest unit of information is a ‘bit’. In a quantum computer, bits are replaced with qubits. Qubits are different from bits because they are set to 1 of 2 values (1 or 0). In the quantum world, the qubit doesn’t have to be in just one of the states, it can be in any proportions of both states at once. This is called superposition. As long as the qubit is unobserved it is in a superposition of probabilities of 0 and 1 and its value (1 or 0) is unpredictable. However, when u measure it, it collapses into one of the definite states (0 or 1).

Superposition is a radical change that has many benefits. For classical bits, they can be in 1 of 2 to the power of 4 different configurations at a time. That is 16 possible combinations, out of which u can use just one. For qubits in superposition, it can be in all of those 16 combinations at once. This number grows exponentially with each qubit. 20 of them can already store over a million values in parallel.

Another aspect of quantum computation is entanglement. A close connection that makes each of the qubits reaction to a change in the other state instantaneously with the disregard how far they are apart. This means when measuring just 1 entangled qubit, you can also directly deduce the properties of its partners without observing the other qubit specifically.

Qubit manipulation is an additional aspect of quantum computation. A normal logic gate has a simple set of inputs and produces one definite output. A quantum gate manipulates an input of superposition which rotates probabilities and produces another superposition as it’s output.

Works Cited

1. Preskill, J. (2018). Quantum Computing in the NISQ era and beyond. Quantum, 2, 79.
2. Nielsen, M. A., & Chuang, I. L. (2010). Quantum Computation and Quantum Information: 10th Anniversary Edition. Cambridge University Press.
3. Arute, F., Arya, K., Babbush, R., Bacon, D., Bardin, J. C., Barends, R., ... & Boixo, S. (2019). Quantum supremacy using a programmable superconducting processor. Nature, 574(7779), 505-510.
4. Kitaev, A. Y. (2002). Fault-tolerant quantum computation by anyons. Annals of Physics, 303(1), 2-30.
5. Ladd, T. D., Jelezko, F., Laflamme, R., Nakamura, Y., Monroe, C., & O’Brien, J. L. (2010). Quantum computers. Nature, 464(7285), 45-53.
6. Shor, P. W. (1994). Algorithms for quantum computation: discrete logarithms and factoring. In Proceedings 35th Annual Symposium on Foundations of Computer Science (pp. 124-134). IEEE.
7. Steane, A. M. (1998). Quantum computing. Reports on Progress in Physics, 61(2), 117.
8. Vandersypen, L. M., & Chuang, I. L. (2005). NMR techniques for quantum control and computation. Reviews of Modern Physics, 76(4), 1037.
9. Ladd, T. D., Jelezko, F., Laflamme, R., Nakamura, Y., Monroe, C., & O’Brien, J. L. (2010). Quantum computers. Nature, 464(7285), 45-53.
10. Montanaro, A. (2016). Quantum algorithms: an overview. npj Quantum Information, 2(1), 1-14.