At A Glance – Quantum Advantage

When quantum computers become more powerful than traditional machines

Quantum computers have the potential to greatly surpass their classical counterparts in processing power, speed and functionality. However, what is possible in theory is not always easy to achieve in practice. Building working quantum computers is extremely difficult, due to the highly precise conditions needed to create qubits, and the challenge of interpreting results generated by a quantum machine.

In spite of these obstacles, functioning quantum computers have been created. Unfortunately, they don’t yet have the same abilities as traditional computers, and this milestone remains some way off for now. In the past, the term quantum supremacy was used to describe the point at which quantum computers would overtake classical machines. More recently, the term quantum advantage has come into use to describe this phenomenon. When quantum computers can be proven to have significant performance advantages in computation speed, memory requirements – or simply by making something possible that wasn’t possible before – we will have achieved quantum advantage.

Connected to the concept of quantum advantage is quantum volume. Coined by researchers at IBM, this metric analyses several aspects of a quantum computer’s performance, including the number of qubits, connectivity, the performance of the software stack and any algorithm errors that creep into calculations. Quantum volume was specifically designed to measure how well quantum computers can process complex algorithms – mirroring the kinds of problems that will be put to quantum machines in the real world.

Unlike previous quantum computing metrics, which focussed on the number of qubits in a device, quantum volume analyses the performance of the entire computer system. It is designed to measure how many operations the computer can perform before too many errors occur, or before the qubits fall out of their quantum state and can no longer be used for calculations. According to IBM, in order for us to achieve quantum advantage by the 2020s, quantum volume will need to at least double every year.

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