Ciro Santilli @cirosantilli  40

It takes time for the quantum state to evolve. So in order to have a deep quantum circuit, we need longer coherence times.

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.

Bibliography:

Only NP-intermediate, which includes notably integer factorization:

Source on GitHub: github.com/stephenjordan/stephenjordan.github.io

The most comprehensive list is the amazing curated and commented list of quantum algorithms as of 2020.

English translation of papers that include the original Quantization as an Eigenvalue Problem by Schrödinger (1926).

Published on Nature at www.nature.com/articles/122990a0 and therefore still paywalled there as of 2023, it's ridiculous.

In 2024 it will fall into the public domain in the US.