A quantum computer's cooling system keeps its quantum chips at temperatures close to absolute zero. Only under these conditions can the chips exhibit the quantum properties that make quantum computing possible (artistic impression). CREDIT B. Schröder/HZDR

Bigger Quantum Computers Could Freeze Up Instead of Speeding Up

A quirk of quantum measurement could stop one whole class of quantum computer in its tracks. The more qubits you add, the smaller the energy gap the machine relies on becomes, while noise from the surroundings goes on checking up on it just as often as before. All that checking holds the calculation still.