Quantum computing in 2023: Major theoretical developments

Wonder what are the groundbreaking developments of quantum computing in 2023?

In the theoretical domain, my two top picks are:

1. Improved Quantum Factoring Algorithms:

For nearly three decades, Shor’s algorithm with its polynomial-time factoring capabilities, was the most appealing example of the practical usefulness of quantum computers in "classical" computing problems rather than simulating quantum mechanics itself. In the past year, Oded Regev found an improvement in the size of factoring circuit, meaning the number of gates required to perform the task [1].?But his algorithm requires substantially more number of qubits. Eventually and building upon Regev's work, Seyoon Ragavan and Vinod Vaikuntanathan found another quantum circuit for factoring using only O(n log n) qubits similar to original Shor’s algorithm but with O(n^3/2 log n) numer of gates rather than O(n^2) [2]. You can learn more about the story on Quanta magazine's article about these works.

2. More Powerful Quantum-Error-Correcting Codes:

Sergey Bravyi and the IBM team introduced a novel error-correcting code that surpasses the current gold standard, the surface code [3]. Leveraging the paradigm of low-density parity-check (LDPC) codes, their innovation boasts a higher encoding rate, resulting in an improved error threshold. As a concrete example, they have shown that these codes allow the preservation of a 12-logical-qubit memory for ten million syndrome cycles, utilizing a total of 288 physical qubits, assuming a mere 0.1% physical error rate. Notably, a similar level of error suppression with surface codes would require about 4000 physical qubits. Check the overview of their findings in another Quanta magazine's article.

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