Quantum coherence describes a qubit’s ability to preserve delicate phase relationships between its quantum states, a property that makes quantum computation possible. When a qubit is coherent, it exists in a controlled superposition, enabling entanglement, which gives quantum computers their power. When coherence is lost – a process called decoherence – the qubit collapses into ordinary classical behaviour, and quantum information is destroyed.
The duration a qubit remains coherent, known as coherence time, determines how many quantum gate operations can be performed before errors overwhelm the calculation. Longer coherence times mean deeper circuits and more complex computations. This is why coherence is a central benchmark when comparing types of qubits.
Silicon spin qubits are notable for their naturally long coherence times, a key reason Quantum Motion chose this approach. By fabricating qubits in silicon using standard CMOS processes and operating at cryogenic temperatures in dilution refrigerators, environmental noise can be suppressed, preserving coherence across large qubit arrays — a critical requirement for scaling toward fault-tolerant quantum computing.