Group Seminar at MPQ and via Zoom: Correcting coherent errors in quantum codes

Prof. Janos Asboth, Budapest University for Technology and Economics
Group Seminar at MPQ in the Herbert-Walther-Lecture Hall and via zoom
Tuesday, July 26, 9.00 (MEZ)

Abstract:

Quantum error correction is a crucial step to building useful quantum computers, needed to maintain precision in deep computations in spite of having faulty components - as long as the error rate is below a threshold value. The most promising quantum error correction scheme to date, the Surface Code [1], uses the entanglement in topological ordered states to distribute/hide logical qubits in several physical qubits. Errors arising from entanglement with the environment can be investigated efficiently for the surface code, however, so-called coherent errors (resulting from 1/f noise) are harder to model. We investigated the combined effects of coherent errors and readout errors on the surface code, using a recently introduced mapping [2] of the surface code to Majorana fermions. We have found numerically an error threshold that is slightly lower for this combination of error sources than if there is no coherence in the errors.

[1]: AG Fowler, M Mariantoni, JM Martinis, AN Cleland, Phys. Rev. A 86, 032324 (2012)

[2]: S Bravyi, M Englbrecht, R Koenig, N Peard, npj Quantum Information, vol. 4, no. 55 (2018)