1In yesterday's lecture, we saw that qubits are extraordinarily sensitive to their surroundings, so today we turn to error correction.
2Even the slightest vibration or change in temperature can destroy the delicate quantum state of a qubit.
3Engineers initially believed that simply shielding the machines from noise would solve the problem entirely.
4However, further experiments revealed that errors arise from inside the system itself, not only from outside interference.
5The leading solution involves spreading the information of one logical qubit across many physical qubits working together.
6Early estimates suggested that a hundred physical qubits would be enough for each logical qubit.
7More recent analysis indicates the true figure may be closer to a thousand, which complicates matters considerably.
8Contrary to what the media often suggests, adding more qubits does not automatically make a computer more powerful.
9What I want to emphasize here is that the quality of qubits matters far more than their quantity.
10A famous experiment was originally scheduled for March, though it was eventually pushed back to late autumn.
11When it finally ran, the team achieved not perfect accuracy but a meaningful reduction in errors.
12In our next session, we will compare the competing designs proposed by universities and by private technology companies.