# Shannon WhitlockUniversity of Strasbourg | UNISTRA · Exotic quantum matter group

Shannon Whitlock

Professor

## About

86

Publications

7,316

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2,569

Citations

## Publications

Publications (86)

Arrays of optically trapped atoms excited to Rydberg states have recently emerged as a competitive physical platform for quantum simulation and computing, where high-fidelity state preparation and readout, quantum logic gates, and controlled quantum dynamics of more than 100 qubits have all been demonstrated. These systems are now approaching the p...

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 unique possibilities to study this intriguing dynamical phenomenon under controlled experimental conditions. He...

Understanding the dynamics of strongly interacting disordered quantum systems is one of the most challenging problems in modern science, due to features such as the breakdown of thermalization and the emergence of glassy phases of matter. We report on the observation of anomalous relaxation dynamics in an isolated XXZ quantum spin system realized b...

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 excitation dynamics of a laser driven gas of Rydberg atoms and the spreading of diseases, which in turn opens up a controlla...

Arrays of optically trapped atoms excited to Rydberg states have recently emerged as a competitive physical platform for quantum simulation and computing, where high-fidelity state preparation and readout, quantum logic gates and controlled quantum dynamics of more than 50 qubits have all been demonstrated. These systems are now approaching the poi...

We propose a mechanism to realize high-yield molecular formation from ultracold atoms. Atom pairs are continuously excited by a laser, and a collective decay into the molecular ground state is induced by a coupling to a lossy cavity mode. Using a combination of analytical and numerical techniques, we demonstrate that the molecular yield can be impr...

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 universa...

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...

Two-dimensional (2D) spectroscopy uses multiple electromagnetic pulses to infer the properties of a complex system. A paradigmatic class of target systems are molecular aggregates, for which one can obtain information on the eigenstates, various types of static and dynamic disorder and on relaxation processes. However, two-dimensional spectra can b...

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....

Two-dimensional (2D) spectroscopy uses multiple electromagnetic pulses to infer the properties of a complex system. A paradigmatic class of target systems are molecular aggregates, for which one can obtain information on the eigenstates, various types of static and dynamic disorder and on relaxation processes. However, two-dimensional spectra can b...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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 nonadditive, unitary and nonunitary (dissipative) conditional intera...

We propose a mechanism to realize high-yield molecular formation from ultra-cold atoms. Atom pairs are continuously excited by a laser, and a collective decay into the molecular ground state is induced by a coupling to a lossy cavity-mode. Using a combination of analytical and numerical techniques, we demonstrate that the molecular yield can be imp...

Self-organized criticality is an elegant explanation of how complex structures emerge and persist throughout nature¹, and why such structures often exhibit similar scale-invariant properties2–9. Although self-organized criticality is sometimes captured by simple models that feature a critical point as an attractor for the dynamics10–15, the connect...

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....

We investigate the dipole-mediated transport of Rydberg impurities through an ultracold gas of atoms prepared in an auxiliary Rydberg state. In one experiment, we continuously probe the system by coupling the auxiliary Rydberg state to a rapidly decaying state that realizes a dissipative medium. In situ imaging of the impurities reveals diffusive s...

Understanding the dynamics of strongly interacting disordered quantum systems is one of the most challenging problems in modern science, due to features such as the breakdown of thermalization and the emergence of glassy phases of matter. We report on the discovery of anomalous slow relaxation dynamics in an isolated quantum spin system realized by...

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 inte...

This article reviews the development in our laboratory of magnetic lattices comprising periodic arrays of magnetic microtraps created by patterned magnetic films to trap periodic arrays of ultracold atoms. Recent achievements include the realisation of multiple Bose-Einstein condensates in a 10 micron-period one-dimensional magnetic lattice; the fa...

This article reviews the development in our laboratory of magnetic lattices comprising periodic arrays of magnetic microtraps created by patterned magnetic films to trap periodic arrays of ultracold atoms. Recent achievements include the realisation of multiple Bose-Einstein condensates in a 10 \(\mu\)m-period one-dimensional magnetic lattice; the...

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...

We present the experimental realization and characterization of an atomic clock 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 Ramsey interference signals can be used to precisely measure the Rydberg atom-light...

We investigate the dipole mediated transport of Rydberg impurities through an ultracold gas of atoms excited to an auxiliary Rydberg state. In one experiment we continuously probe the system by coupling the auxiliary Rydberg state to a rapidly decaying state which realizes a dissipative medium. In-situ imaging of the impurities reveals diffusive sp...

We experimentally and theoretically investigate the nonequilibrium phase structure of a well-controlled driven-dissipative quantum spin system governed by the interplay of coherent driving, spontaneous decay, and long-range spin-spin interactions. We discover that the rate of population loss provides a convenient macroscopic observable that exhibit...

Self organisation provides an elegant explanation for how complex structures emerge and persist throughout nature and society. Surprisingly often, these self-organised structures are found to exhibit remarkably similar fractal-like or scale-invariant properties. While this is sometimes captured by simple models featuring a critical point as an attr...

How do isolated quantum systems approach an equilibrium state? We experimentally and theoretically address this question for a prototypical spin system formed by ultracold atoms prepared in two Rydberg states with different orbital angular momenta. By coupling these states with a resonant microwave driving we realize a dipolar XY spin-1/2 model in...

We present a versatile laser system which provides more than 1.5W of narrowband light, tunable in the range from 455-463 nm. It consists of a commercial Titanium-Sapphire laser which is frequency doubled using resonant cavity second harmonic generation and stabilized to an external reference cavity. We demonstrate a wide wavelength tuning range com...

We propose a scheme to simulate lattice spin models based on strong and long-range interacting Rydberg atoms stored in a large-spacing array of magnetic microtraps. Each spin is encoded in a collective spin state involving a single $nP$ Rydberg atom excited from an ensemble of ground-state alkali atoms prepared via Rydberg blockade. After the excit...

We present combined measurements of the spatially-resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a...

We review recent developments in the use of magnetic lattices as a complementary tool to optical lattices for trapping periodic arrays of ultracold atoms and degenerate quantum gases. Recent advances include the realisation of Bose–Einstein condensation in multiple sites of a magnetic lattice of one-dimensional microtraps, the trapping of ultracold...

The emergence of correlations in complex many-body systems can be accompanied by unexpectedly simple scaling laws which signal new physical regimes or universal relations between otherwise very different physical systems. We demonstrate that non-equilibrium scaling laws can reveal the different regimes of strongly-interacting quantum systems driven...

We theoretically analyze the interactions and decay rates for atoms dressed
by multiple laser fields to strongly interacting Rydberg states using a quantum
master equation approach. In this framework a comparison of two-level and
three-level Rydberg-dressing schemes is presented. We identify a resonant
enhancement of the three-level dressed interac...

We investigate the transport of excitations through a chain of atoms with
non-local dissipation introduced through coupling to additional short-lived
states. The system is described by an effective spin-1/2 model where the ratio
of the exchange interaction strength to the reservoir coupling strength
determines the type of transport, including coher...

We show that an array of ultracold Rydberg atoms embedded in a laser driven
background gas can serve as an aggregate for simulating exciton dynamics and
energy transport with a controlled environment. Spatial disorder and
decoherence introduced by the interaction with the background gas atoms can be
controlled by the laser parameters. This allows f...

LOT-QuantumDesign GmbH. Im Tiefen See 58. D-64293 Darmstadt. +49 6151 8806 0. info@lot-qd.de. www.lot-qd.com/ccd Application Note Technological and scientific progress in atomic, molecular and optical physics has enabled a new level of control over light and matter and even individual atoms and photons. Considerable effort has been directed at obse...

We report site-resolved radio-frequency spectroscopy measurements of Bose-Einstein condensates of $^{87}\mathrm{Rb}$ atoms in about 100 sites of a one-dimensional (1D) 10-$$\mu${}\mathrm{m}$-period magnetic lattice produced by a grooved magnetic film plus bias fields. Site-to-site variations of the trap bottom, atom temperature, condensate fraction...

In an ensemble of laser-driven atoms involving strongly interacting Rydberg
states, the excitation probability is usually strongly suppressed. In contrast,
here we identify a regime in which the steady-state Rydberg excited fraction is
enhanced by the interaction. This effect is associated with the build-up of
many-body coherences, induced by coher...

We report site-resolved radiofrequency spectroscopy measurements of
Bose-Einstein condensates of 87Rb atoms in about 100 sites of a one-dimensional
10 micron-period magnetic lattice produced by a grooved magnetic film plus bias
fields. Site-to-site variations of the trap bottom, atom temperature,
condensate fraction and chemical potential indicate...

We report on the design, fabrication and characterization of magnetic
nanostructures to create a lattice of magnetic traps with sub--micron period
for trapping ultracold atoms. These magnetic nanostructures were fabricated by
patterning a Co/Pd multilayered magnetic film grown on a silicon substrate
using high precision e-beam lithography and react...

Rate equation models are extensively used to describe the many-body states of laser driven atomic gases. We show that the properties of the rate equation model used to describe nonlinear optical effects arising in interacting Rydberg gases can be understood by considering the excitation of individual superatoms. From this we deduce a simple semiana...

Rate equation models are extensively used to describe the many-body states of
laser driven atomic gases. We show that the properties of the rate equation
model used to describe nonlinear optical effects arising in interacting Rydberg
gases can be understood by considering the excitation of individual
super-atoms. From this we deduce a simple semi-a...

We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional atomic gas. We measure asymmetric excitation spectra and increased second and third order statistical moments of the Rydberg number distribution, from which we determine the average aggregate size. Estimating rates for different...

Electronically highly excited (Rydberg) atoms experience quantum-state changing interactions similar to Förster processes found in complex molecules, offering a model system to study the nature of dipole-mediated energy transport under the influence of a controlled environment. We demonstrate a nondestructive imaging method to monitor the migration...

Recent developments in the study of ultracold Rydberg gases demand an
advanced level of experimental sophistication, in which high atomic and optical
densities must be combined with excellent control of external fields and
sensitive Rydberg atom detection. We describe a tailored experimental system
used to produce and study Rydberg-interacting atom...

We report the realization of a periodic array of Bose-Einstein condensates (BECs) of Rb87 F=1 atoms trapped in a one-dimensional magnetic lattice close to the surface of an atom chip. A clear signature for the onset of BEC in the magnetic lattice is provided by in situ site-resolved radio-frequency spectra, which exhibit a pronounced bimodal distri...

Interfacing light and matter at the quantum level is at the heart of modern
atomic and optical physics and enables new quantum technologies involving the
manipulation of single photons and atoms. A prototypical atom-light interface
is electromagnetically induced transparency, in which quantum interference
gives rise to hybrid states of photons and...

We report the sudden and spontaneous evolution of an initially correlated gas
of repulsively interacting Rydberg atoms to an ultracold plasma. Under
continuous laser coupling we create a Rydberg ensemble in the strong blockade
regime, which at longer times undergoes an ionization avalanche. By combining
optical imaging and ion detection, we access...

We propose a new all-optical method to image individual Rydberg atoms embedded within dense gases of ground state atoms. The scheme exploits interaction-induced shifts on highly polarizable excited states of probe atoms, which can be spatially resolved via an electromagnetically induced transparency resonance. Using a realistic model, we show that...

We report the realization of trapping of 87Rb | F=1, mF = −1〉 atoms at temperature of 1–2 μK in a 10 μm-period 1D magnetic lattice constructed from a TbGdFeCo magnetic microstructure on an atom chip.

We propose a new all-optical method to image individual atoms within dense
atomic gases. The scheme exploits interaction induced shifts on highly
polarizable excited states, which can be spatially resolved via an
electromagnetically induced transparency resonance. We focus in particular on
imaging strongly interacting many-body states of Rydberg at...

We investigate a one-dimensional two-component Bose gas near the point
of state-independent interactions. At this specific point the system is
integrable, in the sense that exact (thermodynamic) Bethe Ansatz
solutions can be applied locally. In the experiments, we employ an atom
chip and the magnetically trappable clock states in ^87Rb.
State-depen...

We have studied the transition from two to three dimensions in a low temperature weakly interacting 6Li Fermi gas. Below a critical atom number N(2D) only the lowest transverse vibrational state of a highly anisotropic oblate trapping potential is occupied and the gas is two dimensional. Above N(2D) the Fermi gas enters the quasi-2D regime where sh...

We demonstrate improved detection of small trapped atomic ensembles through advanced postprocessing and optimal analysis of absorption images. A fringe-removal algorithm reduces imaging noise to the fundamental photon-shot-noise level and proves beneficial even in the absence of fringes. A maximum-likelihood estimator is then derived for optimal at...

Experiments on ultracold gases offer unparalleled opportunities to explore quantum many-body physics, with excellent control over key parameters including temperature, density, interactions and even dimensionality. In some systems, atomic interactions can be adjusted by means of magnetic Feshbach resonances, which have played a crucial role in real...

We introduce a general method for designing tailored lattices of magnetic microtraps for ultracold atoms, on the basis of patterned permanently magnetized films. A fast numerical algorithm is used to automatically generate patterns which provide optimal atom confinement while respecting desired lattice symmetries and trap parameters. The algorithm...

We have produced a two-dimensional lattice of microscopic traps above a magnetic-film atom chip. A few hundred optically resolved microtraps, each holding tens to a few hundred ^87Rb atoms, are cooled to quantum degeneracy in parallel. For any given site in the lattice we observe squeezing of the shot-to-shot atom number fluctuations to below the P...

We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold coated chip surface. We measure distance dependent shifts (~10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric...