arXiv subjects

T. M. Wintermantel

Publications and source records attributed to T. M. Wintermantel.

5 recordsLinked to original sources

arXiv2020

Hydrodynamic stabilization of self-organized criticality in a driven Rydberg gas

Signatures of self-organized criticality (SOC) have recently been observed in an ultracold atomic gas under continuous laser excitation to strongly-interacting Rydberg states [S. Helmrich et al., Nature, 577, 481--486 (2020)]. This creates a unique possibility to study this intriguing dynamical phenomenon, e.g., to probe its robustness and universality, under controlled experimental conditions. Here we examine the self-organizing dynamics of a driven ultracold gas and identify an unanticipated feedback mechanism, which is especially important for systems coupled to thermal baths. It sustains an extended critical region in the trap center for a notably long time via hydrodynamic transport of particles from the flanks of the cloud toward the center. This compensates the avalanche-induced atom loss and leads to a characteristic flat-top density profile, providing an additional experimental signature for SOC and minimizing effects of inhomogeneity on the SOC features.

cond-mat.quant-gas↗

arXiv2020

Epidemic growth and Griffiths effects on an emergent network of excited atoms

Whether it be physical, biological or social processes, complex systems exhibit dynamics that are exceedingly difficult to understand or predict from underlying principles. Here we report a striking correspondence between the collective excitation dynamics of a laser driven ultracold gas of Rydberg atoms and the spreading of diseases, which in turn opens up a highly controllable experimental platform for studying non-equilibrium dynamics on complex networks. We find that the competition between facilitated excitation and spontaneous decay results in a fast growth of the number of excitations that follows a characteristic sub-exponential time dependence which is empirically observed as a key feature of real epidemics. Based on this we develop a quantitative microscopic susceptible-infected-susceptible (SIS) model which links the growth and final excitation density to the dynamics of an emergent heterogeneous network and rare active region effects associated to an extended Griffiths phase. This provides physical insights into the nature of non-equilibrium criticality in driven many-body systems and the mechanisms leading to non-universal power-laws in the dynamics of complex systems.

physics.atom-ph↗

arXiv2020

Unitary and non-unitary quantum cellular automata with Rydberg arrays

We propose a physical realization of quantum cellular automata (QCA) using arrays of ultracold atoms excited to Rydberg states. The key ingredient is the use of programmable multifrequency couplings which generalize the Rydberg blockade and facilitation effects to a broader set of non-additive, unitary and non-unitary (dissipative) conditional interactions. Focusing on a 1D array we define a set of elementary QCA rules that generate complex and varied quantum dynamical behavior. Finally we demonstrate theoretically that Rydberg QCA is ideally suited for variational quantum optimization protocols and quantum state engineering by finding parameters that generate highly entangled states as the steady state of the quantum dynamics.

quant-ph↗

arXiv2019

Preparation of hundreds of microscopic atomic ensembles in optical tweezer arrays

We present programmable two-dimensional arrays of microscopic atomic ensembles consisting of more than 400 sites with nearly uniform filling and small atom number fluctuations. Our approach involves direct projection of light patterns from a digital micromirror device with high spatial resolution onto an optical pancake trap acting as a reservoir. This makes it possible to load large arrays of tweezers in a single step with high occupation numbers and low power requirements per tweezer. Each atomic ensemble is confined to $\sim 1\,μ$m$^3$ with a controllable occupation from 20 to 200 atoms and with (sub)-Poissonian atom number fluctuations. Thus they are ideally suited for quantum simulation and for realizing large arrays of collectively encoded Rydberg-atom qubits for quantum information processing.

physics.atom-ph↗

arXiv2019

Realization of a Rydberg-dressed Ramsey interferometer and electrometer

We present the experimental realization and characterization of a Ramsey interferometer based on optically trapped ultracold potassium atoms, where one state is continuously coupled by an off-resonant laser field to a highly-excited Rydberg state. We show that the observed interference signals can be used to precisely measure the Rydberg atom-light coupling strength as well as the population and coherence decay rates of the Rydberg-dressed states with sub-kilohertz accuracy and for Rydberg state fractions as small as one part in $10^{6}$. We also demonstrate an application for measuring small, static electric fields with high sensitivity. This provides the means to combine the outstanding coherence properties of Ramsey interferometers based on atomic ground states with a controllable coupling to strongly interacting states, thus expanding the number of systems suitable for metrological applications and many-body physics studies.

physics.atom-ph↗