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Donnerstag, 29.02.2024, 16:00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
Dr. Jin Yan, WIAS Berlin:
Dichotomic randomness in simple and complex systems
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
Many complex systems are a combination of deterministic and stochastic dynamics. Some systems can be understood by applying random perturbation theory to the underlying deterministic dynamics. However, generally the randomness may not necessarily be small and could consist of any type of stochasticity. Here, we consider a simplest case where only two types (i.e., dichotomic) of dynamics are generated randomly in time, and explore in (1) a simple piecewise-linear random system where either an expanding or contracting map is selected at each time iteration, and (2) a system of coupled rotors kicked with temporally correlated random sequences. In both examples, we illustrate analytically and numerically their rich dynamical behaviour.

Veranstalter
WIAS Berlin
Donnerstag, 29.02.2024, 10:00 Uhr (WIAS-405-406)
Software and Data Seminar
Dr. Jan Philipp Thiele, WIAS:
Advanced git: stashing, rebasing, bug hunting and the likes
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406

Veranstalter
WIAS Berlin
Mittwoch, 28.02.2024, 14:00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
Lasse Ermoneit, WIAS Berlin:
Optimal control of a quantum bus for scalable semiconductor quantum computing architectures
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
Scaling up quantum processors to a large number of qubits to enable the implementation of error-correction algorithms is one of the major challenges on the path to realizing universal quantum computers. Spin qubits in gate-defined SiGe quantum dots provide excellent prospects for scalability, however the lithographic processing, signal routing and wiring of large qubit arrays at a small footprint poses a significant challenge [1]. One possible solution could be to separate the qubit register into small dense qubit arrays, which are interconnected by a quantum bus that allows for coherent transfer of quantum information by physically moving electrons between distant nodes along a channel [2]. Limitations in qubit shuttling arise from the interaction of the electron with material defects within the channel that can cause non-adiabatic transitions to excited states. As excited (orbital) states have a modified effective g-factor, this results in an accumulation of a random phase which finally diminishes the fidelity. In this contribution, we theoretically explore the capabilities for bypassing defect centers using optimally engineered control signals that allow for a quasi-adiabatic passage of the electron through the channel without reducing the velocity. Our approach is based on quantum optimal control theory and Schrödinger wave packet propagation using realistic potential landscapes.
References:
[1] Vandersypen et al., npj Quantum Inf. 3, 34 (2017)
[2] Langrock et al., PRX Quantum 4, 020305 (2023)
Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - The Berlin Mathematics Research Center MATH+ (EXC-2046/1, project ID 390685689).

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Forschungsseminar Mathematische Modelle der Photonik

Veranstalter
WIAS Berlin