Christoph Adelsberger


Department of Physics
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland

email:view address

tel: +41 61 207 36 95

Short CV

2019-present: Ph.D. student in the Condensed Matter Theory & Quantum Computing group at the University of Basel, supervisors: Prof. D. Loss and Prof. J. Klinovaja
2016-2019:Master of Science in Physics, University of Konstanz
Master's thesis: "Cavity Quantum Electrodynamics with spin and valley", supervisor: Prof. Guido Burkhard
2013-2016:Bachelor of Science in Physics, University of Konstanz
Bachelor's thesis: "New materials' exploration and atomic level control for future nano devices", supervisors: Prof. Elke Scheer and Prof. Toyohiro Chikyow


Show all abstracts.

1.  Squeezed hole spin qubits in Ge quantum dots with ultrafast gates at low power
Stefano Bosco, Mónica Benito, Christoph Adelsberger, and Daniel Loss.

Hole spin qubits in planar Ge heterostructures are one of the frontrunner platforms for scalable quantum computers. In these systems, the spin-orbit interactions permit efficient all-electric qubit control. We propose a minimal design modification of planar devices that enhances these interactions by orders of magnitude and enables low power ultrafast qubit operations in the GHz range. Our approach is based on an asymmetric potential that strongly squeezes the quantum dot in one direction. This confinement-induced spin-orbit interaction does not rely on microscopic details of the device such as growth direction or strain, and could be turned on and off on demand in state-of-the-art qubits.

2.  Electric-field control and noise protection of the flopping-mode spin qubit
M. Benito, X. Croot, C. Adelsberger, S. Putz, X. Mi, J. R. Petta, and G. Burkard.
Phys. Rev. B 100, 125430 (2019); arXiv:1904.13117.

We propose and analyze a “flopping-mode” mechanism for electric dipole spin resonance based on the delocalization of a single electron across a double quantum dot confinement potential. Delocalization of the charge maximizes the electronic dipole moment compared to the conventional single-dot spin resonance configuration. We present a theoretical investigation of the flopping-mode spin qubit properties through the crossover from the double- to the single-dot configuration by calculating effective spin Rabi frequencies and single-qubit gate fidelities. The flopping-mode regime optimizes the artificial spin-orbit effect generated by an external micromagnet and draws on the existence of an externally controllable sweet spot, where the coupling of the qubit to charge noise is highly suppressed. We further analyze the sweet spot behavior in the presence of a longitudinal magnetic field gradient, which gives rise to a second-order sweet spot with reduced sensitivity to charge fluctuations.

3.  P-type polymer-based Ag2S atomic switch for "tug of war" operation
C. Lutz, T. Hasegawa, T. Tsuchiya, C. Adelsberger, R. Hayakawa, and T. Chikyow.
Jpn. J. Appl. Phys. 56, 06GF03 (2017)

The Ag2S gap-type atomic switch based "tug of war" device is a promising element for building a new type of CMOS free neuromorphic computer-hardware. Since Ag+ cations are reduced during operation of the device, it was thought that the gap-material should be a n-type polymer. In this study, we revealed that the polymer bithiophene–oligoethyleneoxide (BTOE) doped poly(ethylene oxide) (PEO), which was used as gap-material in the first demonstration of the "tug of war", is a p-type polymer. For this we used impedance spectroscopy and transistor measurements. We elaborate on how the electrochemical processes in the "tug of war" devices could be explained in the case of p-type conductive gap-materials.