We present the progress towards constructing of a dipolar quantum gas microscope using dysprosium atoms. This new apparatus combines the single-site resolution of a quantum gas microscope with the long-range and anisotropic interactions found in dipolar quantum gases, allowing for detailed studies of strongly correlated quantum phases. We plan to do this using dysprosium atoms trapped in an...
We present our efforts towards a new quantum simulation and computation platform based on Yb Rydberg atoms in optical tweezers. Based on the so-called OMG Qu-Bit architecture [1] our approach promises efficient and robust options for storage, manipulation and read-out of quantum information based on the two-electron valence structure of Yb. Resource efficient schemes for error correction [2],...
Recent advances in the microscopic optical manipulation of cold atomic systems have extended our experimental control capabilities down to the level of single particles or single excitation quanta, providing exciting opportunities to explore quantum many-body problems with a novel bottom-up perspective. Here, I will describe ongoing work to develop a modern experimental apparatus in...
Dysprosium (Dy), as the most magnetically stable element, offers fascinating prospects for quantum gas research due to its strong anisotropic long-range dipole-dipole interactions competing with tunable short-range contact interactions. These properties have led to the discovery of novel many-body quantum states in recent years, including liquid-like droplets, droplet crystals, and...
Quantum gases with tunable interactions provide a versatile setting to study non-equilibrium dynamics. Here, we study Fermi gases following a rapid quench of the interaction strength and study the subsequent evolution. Within the superfluid phase, these quenches excite oscillations of the order parameter, which we observe directly using Bragg spectroscopy. These amplitude oscillations provide...
Quantum heat engines have been the subject of growing interest in recent years in the emerging field of quantum thermodynamics. Such engines can utilize uniquely quantum many-body effects to enhance the performance of classical engines, implying a quantum advantage. In my contribution, I will introduce and discuss the performance of a quantum many-body Otto cycle operating under a sudden...
Two-component dipolar condensates are now experimentally producible, and we theoretically investigate the nature of supersolidity in this system. In dipole-imbalanced situations we predict the existence of a binary supersolid state in which the two components form a series of alternating immiscible domains. In stark contrast to single-component supersolids, binary supersolids do not require...
Ultracold atoms loaded into higher Bloch bands provide an elegant setting for realizing many-body quantum states that spontaneously break time-reversal symmetry through the formation of chiral orbital order. The applicability of this strategy remains nonetheless limited due to the finite lifetime of atoms in high-energy bands. Here we introduce an alternative framework, suitable for bosonic...
Bose-Einstein condensates (BECs) are excellent systems for quantum sensing applications like navigation, relativistic geodesy and tests of the universality of free fall. The sensitivity of most such atom interferometers increases quadratically with the interrogation time, which makes it beneficial to extend the free fall time. To accomplish this goal NASA has launched the Cold Atom Lab (CAL)...
We present an overview of some aspects of the non-equilibrium dynamics of arrays of atoms/molecules that are coupled by the electromagnetic field, considering both low-frequency (MW) and high-frequency (optical) regimes for the relevant transitions.
Quantum gases of light, as photon or polariton condensates, can be realized in low-dimensional, mostly two-dimensional experimental settings. We have determined the mechanical compressibility of a photon Bose-Einstein condensate realized in a box potential and revealed its equation of state [1].
In our experiment, a photon Bose-Einstein condensate is realized in a dye-solution-filled...
Traid anyons are indistinguishable particles in one dimension with topological exchange statistics that arise from quantizing the configuration space of indistinguishable particles in one dimension with three-body coincidences removed. For abelian traid anyons, when adjacent particles are exchanged, the state transforms as though they were either bosons or fermions. However, the Yang-Baxter...
We define a model of time-continuous measurement of position and momentum of a quantum particle. We assume that meters are arranged in a regular grid in phase space. Each of these detectors is characterized by a coherent state centered around a phase space location $(x_i,p_j)$ which defines a possible outcome of measurement. The post-measurement state is this coherent state. This way the...
I will present the results of our study on temperature sensing with finite-sized strongly correlated systems exhibiting quantum phase transitions. We use the quantum Fisher information (QFI) approach to quantify the sensitivity in the temperature estimation and apply a finite-size scaling framework to link this sensitivity to critical exponents of the system around critical points. We...
We study theoretically and experimentally the charge transport through a dissipative quantum point contact between two fermionic superfluids. Superconducting junctions are known to exhibit multiple Andreev reflections - a high-order cotunneling of a quasiparticle together with multiple Cooper pairs - which gives rise to a current at chemical potential biases below the energy gap. An...
In my contribution I will focus on the recent developments of the studies of dipolar gases and dipolar systems in lattices: these are described by extended or non-standard Hubbard model, exhibit strong correlations and lead to many exotic quantum phenomena. I will start with the first observation of the checkerboard state of indirect excitons in a 2D lattice [2] – a direct continuation of our...
Quantum vortices are generally thought of as funnel-like holes around which a quantum fluid exhibits a swirling flow. In this picture, vortex cores are empty regions where the superfluid density goes to zero.
Here we generalize this framework, by allowing the vortices to have a non-zero mass. The latter may arise for example due to atoms which are distinguishable from the ones composing the...
In 1935, Einstein, Podolsky, and Rosen (EPR) conceived a gedanken experiment which became a cornerstone of quantum technology and still challenges our understanding of reality and locality today. While the experiment has been realized with small quantum systems, a demonstration of the EPR paradox with massive many-particle systems remains an important challenge, as such systems are...
We have created a spatially homogeneous polariton condensate in thermal equilibrium. In-situ, non-destructive measurement of the coherence allows us to extract the quasicondensate fraction. These measurements reveal a striking 7/2 power law for the quasicondensate fraction overly nearly three orders of magnitude of density. The same power law is seen in simulations solving the generic...
Entanglement plays a crucial role in various quantum many-body phenomena, including the thermalization of isolated quantum systems and the information paradox of black holes. Notably, the second-order Rényi entropy (RE), a measure of entanglement, was successfully measured in the system of bosons in an optical lattice. Motivated by this experiment, we investigate the time evolution of the...
In recent years, our group has created homogeneous ultracold Fermi gases in two-dimensional and three-dimensional box potentials. Using Bragg spectroscopy we have determined the dynamic structure factor of spin-balanced superfluids in the BEC-BCS crossover and extracted both the superfluid gap and the critical velocity [1-2]. By directly comparing 2D and 3D superfluids we could directly...
Supersolids are an exotic phase of matter combining the contrasting characteristics of spontaneous continuous translational symmetry breaking in solids and frictionless flow in superfluids. Supersolids were predicted more than fifty years ago in the context of solid Helium [1, 2, 3] and were first observed in the context of ultracold atoms where cavity-mediated interactions [4, 5], dipolar...
Metastability is ubiquitous in nature and is observed through the crossing of an energy barrier toward a configuration of lower energy as, for example, in chemical processes or electron field ionization. In classical many-body systems, metastability naturally emerges in the presence of a first-order phase transition and finds a prototypical example in supercooled vapour. In the last decades,...
Geometrical frustration in strongly correlated systems can give rise to intriguing ordered states such as quantum spin liquids. In this work, we report on recent experimental progress in Fermi gas microscopy demonstrating emergent magnetic states in a Hubbard model with controllable frustration and doping. Using an optical lattice continuously tunable from a square to a triangular geometry, we...
I will discuss a "helical" superfluid, a nonzero-momentum condensate realized by frustrated bosonic on e.g., a honeycomb lattice. At a Bogoliubov level, such a novel state exhibits "smectic" fluctuation that are qualitatively stronger than that of a conventional superfluid. We develop a phase diagram and compute a variety of its physical properties, including the spectrum, structure factor,...
We present results regarding two topics. First, we explore magnetic polarons formed by holes hopping in an anti-ferromagnetic background in a lattice. We develop a non-perturbative theory both for the equilibrium and the non-equilibrium properties and find excellent agreement with experimental results, which is remarkable for a strongly interacting non-equilibrium many-body problem. We end by...
The nature of the flow between two superfluids, as in the Josephson and fountain effects, is often understood in terms of reversible flow carried by an entropy-free, macroscopic wavefunction. While this wavefunction is responsible for many intriguing properties of superfluids and
superconductors, its interplay with excitations in non-equilibrium situations is more subtle and less understood....
Atomic Bose-Einstein condensates represent a controllable quantum many-body playground, in which the degree of coherence and non-equilibrium coupling between coherent (condensed) and incoherent (thermal) components can be tuned by various parameters -- with typical experiments in inhomogeneous traps featuring a centrally-located condensate, surrounded by a thermal cloud, with the two...
Exact solutions for quantum many-body systems are rare but provide valuable insights for the description of universal phenomena. Recently, specific solutions of the Bethe ansatz equations for 1D anisotropic Heisenberg model were found that can carry macroscopic momentum yet no energy on top of the ferromagnetically "vacuum" state, dubbed phantom Bethe states. Consequently, spin helix at...
Verifying quantum simulators by learning the Hamiltonian is essential for future applications. Recently, sample-efficient Hamiltonian learning (HL) methods were developed for lattice systems, realizable with neutral atoms, trapped ions, or superconducting qubits. These methods rely on constraining coupling parameters in a local Hamiltonian ansatz by exact relations among local correlation...
Many of the breakthroughs in quantum science and technology rely on engineering strong Hamiltonian interactions between quantum systems. Typically, strong coupling relies on short-range forces or on placing the systems in high-quality electromagnetic resonators, which restricts the range of the coupling to short distances. We show how a loop of laser light can generate Hamiltonian coupling...
We report on a family of Bose-Hubbard diamond necklaces with $n$ central sites that exhibit quantum local Hilbert space
fragmentation [1]. Such models possess a single-particle spectrum with a flat band, which is composed of compact localized states (CLSs) that occupy the up and down sites of each diamond. Due to the presence of these CLSs, when adding more bosons with on-site interactions,...
The amplitude mode is a fundamental phenomenon that emerges from a broken continuous symmetry. In the framework of Ginzburg-Landau theory, this corresponds to an oscillation of the complex order parameter $\Delta$, which characterizes the long-range order of superfluids and superconductors. Typically, this mode is unstable and decays rapidly into pair-breaking excitations that exist within a...
Solitons are a hallmark feature of nonlinear dynamics. By balancing dispersion with interactions, solitons acquire a persistent nature that makes them observable in many important nonlinear systems. A variety of solitons have been considered in physical realizations including BECs, water tanks, optical fibers, plasmas, magnetic materials and more, making their study a central part of...
I will present several examples of nonergodic dynamics in strongly interacting systems in the presence of the disorder. Those will include (1D) dipolar models, tilted lattices as well as disordered cases.
The first model considered are dipolar bosons in a 1D lattice. By tailoring the transversal confinement one may modify the tail of interactions that profoundly affects the dynamics for...
In recent years, methods for automatic recognition of phase diagrams of quantum systems have gained large interest in the community: Among others, machine learning analysis of the entanglement spectrum has proven to be a promising route. Here, we discuss the possibility of using an experimentally readily accessible proxy, namely the number probability distribution that characterizes...
Important properties of complex quantum many-body systems and their phase diagrams can often already be inferred from the impurity limit. The Bose polaron problem describing an impurity atom immersed in a BEC is a paradigmatic example. However, its description at strong coupling is challenging due to the intricate competition between the emergent impurity-mediated attraction between the bosons...
We observe and study a special ground state of bosons with two spin states in an optical lattice: the spin-Mott insulator, a state that consists of bound pairs that is insulating for both spin and charge transport. Because of the pairing gap created by the interaction anisotropy, it can be prepared with low entropy and can serve as a starting point for adiabatic state preparation. We find that...
The concept of a topological 'Thouless' pump involves the quantised motion of particles in response to a slow, cyclic modulation of external control parameters. Similar to the quantum Hall effect, the Thouless pump is of fundamental interest in physics because it links physically measurable quantities, such as particle currents, to geometric properties of the experimental system, whose...
Ultracold atoms in optical lattices represent an outstanding tool to create and study quantum many-body systems. Combining these lattice systems with the properties of alkaline-earth atoms such as strontium gives rise to exciting research directions. On one hand, sub-wavelength arrays of bosonic strontium exhibit strong cooperative effects in atom-photon scattering, and constitute rich...
On this poster, I present two recent studies on cold-atom dynamics.
Firstly, I will present our proposal to utilize cavity-BEC systems as a rotational sensor, see Ref. [1]. The atoms are set up in an array of Bose-Einstein condensates, and coupled to a single light mode of an optical cavity. The photon emission from the cavity indicates changes in the rotation frequency in real time, which...
I. Knottnerus1, 2, 3, Y.C. Tseng1,2, A. Urech1,2, D. Janse van Rensburg3, R. van Herk3, M. Venderbosch3, Z. Guo3, E. Vredenbregt3, S. Kokkelmans3, R. Spreeuw1,2,
F. Schreck1,2
1University of Amsterdam, Amsterdam
2QuSoft,...
Quasicrystals, a fascinating class of materials with long-range but nonperiodic order, exhibit fascinating properties due to their unique position at the crossroads of long-range-ordered and disordered systems. These include remarkable localization and fractal properties. While such properties are well known for single particles, the strongly-correlated regime remains largely unexplored....
In the last two years, exciting progresses on Bose-Einstein condensations (BEC) of molecules with bosonic atoms have been made. The Chicago group led by Chin has reported the achievement of the BEC of the G-wave Feshbach Cs molecules [1], and its ``super-chemistry”[2]. The Columbia group led by Will has created an ultra-cold gas of Na-Cs ground state molecules closed to BEC [3]. In this talk,...
A paramagnetic-ferromagnetic quantum phase transition is known to occur at zero temperature in a two-dimensional coherently-coupled Bose mixture of dilute ultracold atomic gases provided the interspecies interaction strength is large enough. Here we study the fate of such a transition at finite temperature by performing numerical simulations with the stochastic (projected) Gross-Pitaevskii...
I will present new strategies for engineering gauge theories with atomic platforms. First, I will illustrate the concept of encoding, eliminating partially or completely the gauge degrees of freedom by solving the local conservation laws of gauge theories. Then, I will show how to employ it to enable the realization of 1) topological gauge theories like chiral BF and Chern-Simons theories...
A significant fraction of topological materials has been characterized using symmetry requirements of wave functions. The past three years, however, have witnessed the rise of novel multi-gap dependent topological states, the properties of which go beyond these approaches and are yet to be fully explored. While such systems are thus of active interest already in static settings, most physical...
Cold atom platforms with single particle/spin detection and control offer fascinating opportunities for emerging quantum technologies.
Among quantum simulators atoms trapped in programmable optical tweezer arrays and excited to Rydberg states are nearly ideal systems to study quantum spin models. The short cycle time typically below one second makes modern protocols developed to characterize...
A current challenge in quantum gases is to produce trapped clouds of ultracold ground-state molecules having both an electric and a magnetic dipole moment. These would form a novel platform for investigations of few- and many-body physics, quantum simulation, quantum information and quantum-controlled chemistry. A promising route to achieve this is to combine ultracold alkali and closed-shell...
Ensemble of Rydberg atoms are a unique platform for quantum simulation and quantum computation because of their special properties [1,2]. In our research group, we are developing a novel approach for Rydberg-based quantum simulations and computations, where we use broadband pulsed lasers to excite 87Rb atoms, in Bose-Einstein condensates (BEC), Mott-Insulator (MI) lattice and optical tweezers,...
