What is quantum computing? – The Hindu

The quantum computer

It’s time to introduce the star of this article! The quantum computer is quite different from the regular computer you would use at home, the office, or in a school computer lab. It is a device that utilises quantum mechanics (a field of physics where the behaviour of matter and energy is described and studied at the atomic and sub-atomic levels) to solve complex problems and perform computations faster than a traditional computer. Theoretical physicist Richard Feynman was credited as one of the first scientists to introduce the idea of combining computers with quantum mechanics to ensure efficient computer simulations (creation of digital models and equations to mimic real-world scenarios). Unlike regular computers that use bits, or binary digits, quantum computers operate through the manipulation of qubits.

What are qubits?

Qubits serve as the main contrast between quantum computers and regular computers. A qubit is a two-state fundamental unit of quantum computing. In traditional computers, bits are used for storing and processing data, but have a binary state, only being able to exist as either a zero or a one. Qubits, however, are different, as they can exist as both a zero and a one at the same time! This additionally means that qubits can help the quantum computer accomplish many tasks at once at much higher speeds. Think of it this way: there are two workers, one wearing red and the other wearing blue. In a ‘bit’, only one of the two workers (either red or blue) can work on a provided task at a time. But in a quantum bit, both workers can work on the task at the same time! 

The key components from quantum mechanics that are incorporated into these qubits (or quantum bits) are superposition and entanglement. 

Quantum superposition states that the qubit can exist as both a zero and a one, and can represent many values at the same time, making computing much quicker and more vast.

Quantum entanglement, on the other hand, is when two or more qubits become linked so that one cannot exist independently of the other. If one is measured, the other’s information is instantly known. Think of it as two light bulbs being connected to the same switch. If you were to look at one bulb and turn on the switch, you wouldn’t have to look to know that the other has turned on as well. This allows qubits to work in a unified manner and solve complex problems more quickly and efficiently. 

Applications

When quantum computing began to slowly shift from being a theoretical concept to an experiment, there were many fields that saw its benefits. Within finance, studies have explored the potential of quantum computing to aid in portfolio optimisation (the process by which the best combination of assets is selected for an investment that ensures the highest returns) through the Quantum Approximate Optimization Algorithm (QAOA), which can be used to find near-optimal solutions for problems where the options are finite. This also leads to better decisions being made in businesses, alongside risk analysis and fraud detection.