Mathematical problems of error suppression in single-qubit gates

Seminars

Laboratory of Information Technologies

Seminar of the Scientific Department of Computational Physics

Date and Time: Thursday, 25 September 2025, at 3:00 PM

Venue: room 310, Meshcheryakov Laboratory of Information Technologies

  1. Seminar topic: “On mathematical problems of error suppression in single-qubit gates”

    Authors: Mikhail Babich, Ljudmila Bordag, Arsen Khvedelidze, Dimitar Mladenov

    Speaker: Ljudmila Bordag

    Abstract:

    The main challenge in building quantum computers is implementing logical gates that remain stable under unavoidable systematic errors caused by external noise and experimental imperfections. One promising strategy is to replace a single gate with a tailored composite sequence of single-qubit operations.

    The seminar presents an algorithm for constructing such sequences using two types of single-qubit gates. The approach relies on Lie group theory and spherical geometry, formulating the task as approximating an element of SU(2) by a product of N elements from two one-parameter subgroups. The optimisation criterion is the gate fidelity expressed through the corresponding N Euler angles.

    As a case study, the speakers demonstrate the method with a six-gate sequence, highlighting its potential for systematic error suppression in practical implementations.


  2. Seminar topic: “Do Quantum States Have to Be Continuous? Galois Fields and Multiparticle Quantum Systems”

    Speaker: Vladimir Kornyak

    Abstract:

    The use of infinities in standard quantum mechanics leads to inconsistencies and unphysical artifacts. Replacing the infinite elements in quantum theory with finite structures that arise naturally within the phase-space formulation of quantum mechanics eliminates the issues generated by infinities while reproducing all the results of traditional quantum mechanics. In this approach, Galois fields are a natural means of describing systems of indistinguishable particles. We discuss computational aspects of studying the dynamics of quantum systems over Galois fields.