Quantum error correction codes

Quantum error correction codes | QuTech Academy

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@pierremeynet3703 2 жыл бұрын

Your content is so touching

@brahimboudine4696 5 жыл бұрын

Thank you very much for this great video !

@SashaBakman 4 жыл бұрын

Are the ancilla qubits entangled with the qubits that are part of the logical qubit? If so, by measuring the ancilla qubits, you destroy the state of the qubits you want to "error correct"..

@rigoluna1491 4 жыл бұрын

Could you elaborate?

@AritraDaddy 4 жыл бұрын

You wouldn't necessarily destroy them. For a hypothetical example, suppose you had two physical qubits encoding a single logical qubit such that both physical qubits have the same parity when there is no error (e.g. both are in state 0 with some probability and both are in state 1 otherwise). You can take an extra ancilla qubit and perform two CNOTs, one controlled on each of the two physical qubits, and both targeting the ancilla qubit to check for any errors in your two-qubit logical system. If the state of the ancilla qubit after the two CNOTs is changed compared to the state it was in before, you know there is some error and the two physical qubits dont have the same parity. In this process, you however don't affect the physical qubits' states themselves, as you only control on them for gates and never measure them either. In fact, after measuring the ancilla, you can only say whether the two physical qubits have the same parity or not, but not what the probabilities themselves are, for their being in 00 or 11. By measuring only the ancilla, you just check some property of the physical system; you don't measure it and hence, dont destroy its state.

@daltanionwaves Жыл бұрын

Additionally, the information known to the system is not destroyed with the measurement, and because of the sequential and redundant nature of this quantum system, useful calculations can be performed regardless of the effects of measurement.