Technique that uses multiple non-ideal qubits (physical qubits) to simulate/produce one perfect qubit (logical).
One is philosophically reminded of classical error correction codes, where we also have multiple input bits per actual information bit.
TODO understand in detail. This appears to be a fundamental technique since all physical systems we can manufacture are imperfect.
Part of the fundamental interest of this technique is due to the quantum threshold theorem.
For example, when PsiQuantum raised 215M in 2020, they announced that they intended to reach 1 million physical qubits, which would achieve between 100 and 300 logical qubits.
Video "Jeremy O'Brien: "Quantum Technologies" by GoogleTechTalks (2014)" youtu.be/7wCBkAQYBZA?t=2778 describes an error correction approach for a photonic quantum computer.
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This theorem roughly states that states that for every quantum algorithm, once we reach a certain level of physical error rate small enough (where small enough is algorithm dependant), then we can perfectly error correct.
This algorithm provides the conceptual division between noisy intermediate-scale quantum era and post-NISQ.
Era of quantum computing before we reach physical errors small enough to do perfect quantum error correction as demonstrated by the quantum threshold theorem.
A quantum algorithm that is thought to be more likely to be useful in the NISQ era of quantum computing.
TODO clear example of the computational problem that it solves.
TODO clear example of the computational problem that it solves.
Articles by others on the same topic
Quantum error correction (QEC) is a crucial aspect of quantum computing that aims to protect quantum information from errors due to decoherence, noise, and operational imperfections. Quantum bits, or qubits, are the fundamental units of quantum information. Unlike classical bits, which can be either 0 or 1, qubits can exist in superpositions of both states. This property makes quantum systems particularly susceptible to errors, as even small interactions with the environment can lead to significant loss of information.