Why are quantum computers so error prone?

Quantum error-correction (QEC) schemes work by building redundancy into the information being transmitted in quantum computers.

The quantum states used to encode information in a quantum computer collapse if there is any interaction with the external environment.

Without error correction, the error rate in qubits is roughly 1 in 1,000 versus 1 million million in classical computing bits.

Google’s Willow quantum processor was the first conclusive evidence that QEC can scale up to the large device sizes needed to solve practical problems.

IBM research staff member at IBM explains the process of detecting and correcting errors in quantum computers.

The process is complicated by the fact that you can’t directly measure the states of the physical qubits without causing them to collapse.

Each ancilla qubit interacts with a group of data qubits to check if the sum of their values is odd or even.

Once this is known, an operation can be performed on the logical qubit to fix the error.