arXiv subjects

Christian Marty

Publications and source records attributed to Christian Marty.

4 recordsLinked to original sources

arXiv2025

An InAsSb surface quantum well with in-situ deposited Nb as a platform for semiconductor-superconductor hybrid devices

We present a novel semiconductor-superconductor hybrid material based on a molecular beam epitaxially grown InAsSb surface quantum well with an in-situ deposited Nb top layer. Relative to conventional Al-InAs based systems, the InAsSb surface quantum well offers a lower effective mass and stronger spin-orbit interaction, while the Nb layer has a higher critical temperature and a larger critical magnetic field. The in-situ deposition of the Nb results in a high-quality interface that enables strong coupling to the InAsSb quantum well. Transport measurements on Josephson junctions reveal an induced superconducting gap of 1.3 meV. Furthermore, a planar asymmetric SQUID is realized, exhibiting gate-tunable superimposed oscillations originating from both the individual Josephson junction and the full SQUID loop. The large induced superconducting gap combined with strong spin-orbit interaction position this material as an attractive platform for experiments exploring gate-tunable superconductivity and topological superconducting devices.

cond-mat.supr-con↗

arXiv2024

Memory resistor based in GaAs 2D-bilayers: In and out of equilibrium

Resonant tunneling between closely spaced two dimensional electron gases is a single particle phenomenon that has sparked interest for decades. High tunneling conductances at equal electron densities are observed whenever the Fermi levels of the two quantum wells align. Detuning the Fermi levels out of the resonant 2D-2D tunneling regime causes a negative differential resistance. The negative differential resistance leads to a hysteresis when operating the device in a current driven mode, allowing a bilayer system to function as a volatile memory resistor.

cond-mat.mes-hall↗

arXiv2022

Extracting the lifetime of a synthetic two-level system

The Kerr Parametric Oscillator (KPO) is a nonlinear resonator system that is often described as a synthetic two-level system. In the presence of noise, the system switches between two states via a fluctuating trajectory in phase space, instead of following a straight path. The presence of such fluctuating trajectories makes it hard to establish a precise count or even a useful definition, of the "lifetime" of the state. Addressing this issue, we compare several rate counting methods that allow to estimate a lifetime for the levels. In particular, we establish that a peak in the Allan variance of fluctuations can also be used to determine the levels' lifetime. Our work provides a basis for characterizing KPO networks for simulated annealing where an accurate determination of the state lifetime is of fundamental importance.

cond-mat.mes-hall↗

arXiv2022

Ising machines with strong bilinear coupling

Networks of coupled parametric resonators (parametrons) hold promise for parallel computing architectures. En route to realizing complex networks, we report an experimental and theoretical analysis of two coupled parametrons. In contrast to previous studies, we explore the case of strong bilinear coupling between the parametrons, as well as the role of detuning. We show that the system can still operate as an Ising machine in this regime, even though careful calibration is necessary to ensure that the correct solution space is available. Apart from the formation of split normal modes, new states of mixed symmetry are generated. Furthermore, we predict that systems with $N>2$ parametrons will undergo multiple phase transitions before arriving at a regime that can be equivalent to the Ising problem.

cond-mat.mes-hall↗