The seminar features four presentations by scientists developing techniques that enable the simulation of quantum systems using quantum computing hardware.

Venue: JSC **BR06** (room 4024a in building 14.14), or online: https://webconf.fz-juelich.de/b/hof-v8a-nch-ufh

- May 9th, 10:30am: Carsten Urbach, Bonn University
**Title:**Hamiltonian approach to lattice gauge theories with digitised gauge fields**Abstract:**With the advent of quantum computing and rapidly developing tensor network methods also the simulation of quantum chromodynamics with such technologies comes into reach. This requires the restriction of the well known Kogut-Susskind Hamiltonian for lattice gauge theories to a finite dimensional Hilbert space, which can be achieved by digitising the gauge fields. In this presentation we discuss one approach for doing so for the gauge group SU(2) based on partitionings of the gauge group.

- May 16th, 10:30am: Maurits Tepaske, Bonn University
**Title:**Optimal compression of quantum many-body time evolution operators into brickwall circuits**Abstract:**Near term quantum computers suffer from a degree of decoherence which is prohibitive for high fidelity simulations with deep circuits. An economical use of circuit depth is therefore paramount. For digital quantum simulation of quantum many-body systems, real time evolution is typically achieved by a Trotter decomposition of the time evolution operator into circuits consisting only of two qubit gates. To match the geometry of the physical system and the CNOT connectivity of the quantum processor, additional SWAP gates are needed. I will show that optimal fidelity, beyond what is achievable by simple Trotter decompositions for a fixed gate count, can be obtained by compiling the evolution operator into optimal brickwall circuits for the S=1/2 quantum Heisenberg model on chains and ladders, when mapped to one dimensional quantum processors without the need of additional SWAP gates.

- May 23rd, 10:30am: Lena Funcke, Bonn University
**Title**: Quantum Algorithms for Particle Physics**Abstract**: In this seminar, I will present recent advances towards applying quantum computing to particle physics. Quantum technology offers the prospect to efficiently simulate sign-problem afflicted regimes in lattice field theory, such as the presence of topological terms, chemical potentials, and out-of-equilibrium dynamics. Moreover, quantum computing can be applied to quadratic unconstrained binary optimization problems in collider physics. The path towards quantum computing for (3+1)D particle physics requires many incremental steps, including algorithmic development, hardware improvement, methods for circuit design, as well as error mitigation and correction techniques. I will review these requirements, present new avenues to tackle some of these challenges, and discuss the main bottlenecks and future directions.

- May 31st, 10:30am: Thomas Luu, Forschungszentrum Jülich
**Title**: Optimization Problems on the JUPSI D-Wave System**Abstract**: I present results of initial studies using the FZJ's D-Wave system to solve an internet network optimization problem. I show how one transforms the network optimization problem into an integer linear program (ILP) problem and using the QUBO formalism, demonstrate how the problem is mapped onto the D-Wave system. I present a feasibility and scaling study for performing real-world network optimizations using a quantum annealer. I then discuss a newly proposed physics project to use D-Wave to investigate the strongly-coupled QCD regime. I provide preliminary observations demonstrating the efficacy of D-Wave calculations in this phase space of QCD.

This seminar will be offered in hybrid form (on site and virtual), as a joint CASA Seminar & JSC Computational and Data Science Seminar.