Technological Advancements
Since the industrial revolution, technological advancement has continued to increase its intensity. We see major developments in technological fields like robotics, mass production (automation), AI and IoT. These technologies are starting to change and increase the efficiency of many fields, like healthcare with supportive robots, agriculture with drones and analytics, and city-building with smart technologies and automated cars.
The basis of all of these technologies is computational and processing capability. Scientists have constantly pursued ways to make transistors (basic components of a circuit chip) smaller and make energy and time efficiency better. Now, transistors are reaching the size of an atom. Currently, the quantum computer – computers that operate using phenomena of quantum physics – is expected to provide a breakthrough in technology that allows a further boost in computational and processing capability.
Brief History of Quantum Computing
Here is a brief history. All new concepts in this section will be explained later.
Talk among scientists of the idea of a quantum computer popularised in the 1980s, based on some research that started during the 1960s. They dreamed of a well-rounded quantum computer that could solve any kinds of problems, faster and more efficiently. In 1998, Japanese physicists led by H. Nishimori proposed a different approach – quantum annealing (explained later) – a computer with limited uses but effective in solving optimisation problems. In 2011, D-Wave, a tech company, launched the first commercial quantum computer based on quantum annealing. Recently, big tech companies have joined the field, conducting research to develop the well-rounded types of quantum computers. These companies have provided their quantum computers online for people to use. There is more to come!
Fundamental Concepts of Quantum Computing, Basic Types
In classic computers (which we use in our daily lives), information is stored in bits. Bits can take on values of either 0 or 1. The collection of these bits can express complex information. If you can use 5GB per month on your phone, that amounts to 5 million bytes, or 40 million bits.In quantum computers, instead of normal bits, qubits (short for quantum bits) are used. With its properties, it can store more information efficiently. Qubits use mainly two interesting quantum properties in their computation process.
1 Superposition
Unlike normal bits, qubits can take on values of both 0 and 1 at the same time. This is called superposition. The qubit will take a discrete value only when we test it. This is similar to the Schrodinger’s cat, where a cat in a closed box is both alive and dead until we actually see inside.
With superposition, less computation is needed. To express all combinations of 0s and 1s with 4 classic bits, it would take 24 combinations, or 24 computations. However, qubits can be both 0 and 1 at the same time, so it can express the same amount of information simultaneously.
2 Entanglement
Several qubits can be entangled. When qubits are entangled to each other, if we test the value of one of them, we automatically can deduce the rest. Entangled qubits cannot be described independently of each other. The configuration of entanglement is determined by the requirements and constraints of the problem that the computer is solving. Entanglement makes problem-solving easier for computers.
Now, we will look at the basic types of quantum computers.
1 Quantum annealing computer
Quantum annealing is a concept proposed by Japanese physicists led by H. Nishimori, and the most well-known existing computer is the one created by D-Wave. It attempts to find an optimal solution very efficiently.
Annealing is a word that refers to the process of heating metal or glass and allowing it to cool down slowly. The quantum annealing computer operates in a similar manner. Qubits are induced into superposition (through exposure to a transverse field). At this point, where qubits are in superposition, the computer expresses all possible states and solutions simultaneously. We gradually decrease the energy/effect of the field until all qubits settle on a value that result in the least energy configuration of the entire system. During this process, a phenomenon called quantum tunneling occurs, which is a process of finding the point of minimum energy configuration efficiently. It does not have to compute and compare every combination of solutions.
The use of quantum annealing computers is narrow and specialised. It solves combinatorial optimisation problems very efficiently. The traveling salesman problem is a famous example. A salesman has to visit a given number of cities, and they want to find the shortest possible route. With a classical computer, the problem soon becomes unsolvable in a realistic amount of time because the number of combinations increases exponentially as we increase the number of cities. With a quantum annealing computer, all combinations can be considered simultaneously and we can reach a solution quickly and efficiently.
2 Universal gate quantum computer
A universal gate quantum computer is more complex and broad in its functions, and researchers expect these to be superior versions of current, well-rounded computers. It uses qubits and quantum properties just as quantum annealing did. However, instead of annealing, it uses logic gates. Logic gates exist in both classical and quantum computers. They take a set of inputs from bits and carry out a certain operation. Then, it gives instructions to the computer to perform a certain action.
Quantum gates use the powers of superposition and entanglement. Quantum gates are reversible, which means that unlike classical logic gates, they never lose information. Entangled qubits remain entangled after being put through quantum gates, and we can retrace information from the instructions that the gates give. In a classical computer, the information of bits are lost from the computer as heat.
If this type of quantum computer can be constructed with high enough quality, advanced problems like Shor’s algorithm can be solved. Shor’s algorithm conducts prime factorisation. It is hard for humans and classical computers to find prime factors, which is why we use it for encryption, but quantum computers at its full promise are expected to solve these easily.
Applications
Fields of applications include: materials science, financial modelling, healthcare, logistics, machine learning, and cybersecurity.
For materials science, quantum chemistry simulations have been conducted, and IBM has succeeded in modelling a BeH2 molecule (a molecule is difficult to simulate on a classical computer). For logistics, applications in airline scheduling, car navigation system, traffic, delivery system optimisation for companies are being tested. For cybersecurity, quantum computers actually decrypt current types of encryptions very easily, but they may also be used to devise stronger codes and measures.
Big Tech Companies, New Research, and age of NISQ
As mentioned before, many big tech companies are entering the field of quantum computing, including Alibaba, D-Wave, IBM, Microsoft and Google. A lot of them provide quantum computers online for people to use, as well as educational articles and tutorials.
Quantum computers are starting to be used in the commercial world already. D-Wave currently works in collaboration with DENSO for traffic flow optimisation, Tohoku university for tsunami evacuation modelling, and Nomura Securities for financial portfolio optimisation. IBM launched IBM Q System One, a 53 qubit quantum computer for commercial use, and currently works in collaboration with educational institutions like the University of Oxford, MIT, Keio University and Tokyo University, as well as companies like Mizuho, Mitsubishi Chemical, and Goldman Sachs. Research and development of quantum computers is most extensive in the US, Japan, China and the UK, which are four highest ranking countries for number of patents related to quantum computing.
It is still difficult to build a quantum computer that is as well-rounded as a classical computer. This is because we need more qubits to store and compute more information but adding qubits makes maintaining a low error rate (of computation) difficult. Current quantum computers use superconductivity to reduce irrelevant noise and increase the amount of time qubits can remain with quantum principles. Researchers are also working on finding useful algorithms to solve, attempting to select the right problems – hard for classical computers but easy for quantum computers.
In the long-term, researchers aim to build a quantum computer that can solve all kinds of problems, but this full promise is still far away. Google recently claimed to have reached quantum supremacy – the ability of a quantum computer to solve problems that classical computers could not or would take too much time. This is a step towards a well-rounded quantum computer.
Meanwhile, in the current commercial world, NISQ, or noisy intermediate-scale quantum technologies are spreading. They are quantum computers that are beneficial in limited, specialised fields, but can enhance performance when integrated with classical computers.
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