Coherence times in quantum computing have increased by orders of magnitude since the early 2000s. If this exponential progress continues, coherence times measured in seconds or even minutes could be achieved in the near future.

When discussing the latest quantum computers, most people tend to focus on the number of quantum bits (or qubits) in a system. However, while qubit counts are a very important factor, another key metric is coherence time, which measures how long a qubit can hold information.

In order to generate complex mathematical calculations, a qubit needs to hold information for as long as possible. That requires physical qubits to remain highly isolated from the surrounding environment. When a qubit is disrupted by external stimuli – such as background noise from vibrations, temperature changes or stray electromagnetic fields – information about the state of that qubit “leaks out” in a process known as decoherence. This can ruin the ability to exploit any quantum effects. Longer coherence times enable more quantum gates to be utilised before this occurs, resulting in more complex calculations.