Quantum computer is a technology that utilizes the "superposition principle" of quantum mechanics.It is said that problems such as prime factorization and quantum chemistry calculations can be solved at ultra-high speed, and its development is underway all over the world.

　Since an actual quantum computer is made by combining elements (qubits) with a slight error, it is necessary to have "quantum error correction", which is a mechanism to continue calculation while correcting it.For the design, it is important to estimate how much the error of the element can be reduced to make the error correction successful.

　However, due to the high speed of quantum computers, the calculation of this estimate cannot keep up with ordinary computers, and the dilemma that "quantum computers are necessary for designing quantum computers" arises.

　The research group has shown that the mechanism by which a quantum computer corrects quantum errors can be regarded as the same as the physical model that represents the motion of "fermions."The mechanism that seems to go through a complicated superposition state is replaced with a simple time change that can be calculated by a normal computer by considering it as the motion of particles.This makes it possible to calculate the performance required for an element considering quantum error, which was conventionally impossible, at high speed and accurately with a normal computer.
　
　This method is expected to promote the development of practical quantum computers.In addition, the discovery that some of the complicated superposition states are "only apparent" can be said to be closer to clarifying the fundamental problem of "why quantum computers are so fast".

Paper information:[Physical Review Letters] Efficient simulation of quantum error correction under coherent error based on nonunitary free-fermionic formalism