arXiv subjects

Tanish Satoor

Publications and source records attributed to Tanish Satoor.

9 recordsLinked to original sources

arXiv2026

Suppression and enhancement of bosonic stimulation by atomic interactions

The tendency of identical bosons to bunch, seen in the Hanbury Brown-Twiss effect and Bose-Einstein condensation, is a hallmark of quantum statistics. This bunching can enhance the rates of fundamental processes such as atom-atom and atom-light scattering when atoms scatter into already occupied states. For non-interacting bosons, the enhancement of light scattering follows directly from the occupation of the atom's final momentum state. Here, we study scattering between off-resonant light and atoms in a quasi-homogeneous Bose gas with tunable interactions and show that even weak interactions, which do not significantly alter the momentum distribution, strongly affect atom-light scattering. Changes in local atomic correlations suppress the bosonic enhancement under weak repulsive interactions and increase the scattering rate under attractive ones. Moreover, if the interactions are rapidly tuned, light scattering reveals correlation dynamics that are orders of magnitude faster than the collisional dynamics of the momentum-space populations. Its extreme sensitivity to correlation effects makes off-resonant light scattering a powerful probe of many-body physics in ultracold atomic gases.

cond-mat.quant-gas↗

arXiv2024

Observation of an Inverse Turbulent-Wave Cascade in a Driven Quantum Gas

We observe an inverse turbulent-wave cascade, from small to large lengthscales, in a driven homogeneous 2D Bose gas. Starting with an equilibrium condensate, we drive the gas isotropically on a lengthscale much smaller than its size, and observe a nonthermal population of modes with wavelengths larger than the drive one. At long drive times, the gas exhibits a steady nonthermal momentum distribution. At lengthscales increasing from the drive one to the system size, this distribution features in turn: (i) a power-law spectrum with an exponent close to the analytical result for a particle cascade in weak-wave turbulence, and (ii) a spectrum reminiscent of a nonthermal fixed point associated with universal coarsening in an isolated 2D gas. In further experiments, based on anisotropic driving, we reveal the complete qualitative picture of how the steady-state cascade forms.

cond-mat.quant-gas↗

arXiv2024

Realization of an atomic quantum Hall system in four dimensions

Modern condensed matter physics relies on the concept of topology to classify matter, from quantum Hall systems to topological insulators. Engineered systems, benefiting from synthetic dimensions, can potentially give access to novel topological states predicted in dimensions $D > 3$. We report the realization of an atomic quantum Hall system evolving in four dimensions (4D), with two spatial dimensions and two synthetic ones encoded in the large spin of dysprosium atoms. The non-trivial topology is evidenced by measuring a quantized electromagnetic non-linear response and observing anisotropic hyperedge modes. We also excite non-planar cyclotron motion, contrasting with its circular equivalents in $D\leq3$. Our work opens to the investigation of strongly-correlated topological liquids in 4D generalizing fractional quantum Hall states.

cond-mat.quant-gas↗

arXiv2024

Universal Coarsening in a Homogeneous Two-Dimensional Bose Gas

Coarsening of an isolated far-from-equilibrium quantum system is a paradigmatic many-body phenomenon, relevant from subnuclear to cosmological lengthscales, and predicted to feature universal dynamic scaling. Here, we observe universal scaling in the coarsening of a homogeneous two-dimensional Bose gas, with exponents that match analytical predictions. For different initial states, we reveal universal scaling in the experimentally accessible finite-time dynamics by elucidating and accounting for the initial-state-dependent prescaling effects. The methods we introduce establish direct comparison between cold-atom experiments and non-equilibrium field theory, and are applicable to any study of universality far from equilibrium.

cond-mat.quant-gas↗

arXiv2021

Laughlin's topological charge pump in an atomic Hall cylinder

The quantum Hall effect occuring in two-dimensional electron gases was first explained by Laughlin, who envisioned a thought experiment that laid the groundwork for our understanding of topological quantum matter. His proposal is based on a quantum Hall cylinder periodically driven by an axial magnetic field, resulting in the quantized motion of electrons. We realize this milestone experiment with an ultracold gas of dysprosium atoms, the cyclic dimension being encoded in the electronic spin and the axial field controlled by the phases of laser-induced spin-orbit couplings. Our experiment provides a straightforward manifestation of the non-trivial topology of quantum Hall insulators, and could be generalized to strongly-correlated topological systems.

cond-mat.quant-gas↗

arXiv2021

Simulating two-dimensional dynamics within a large-size atomic spin

Encoding a dimension in the internal degree of freedom of an atom provides an interesting tool for quantum simulation, facilitating the realization of artificial gauge fields. We propose an extension of the synthetic dimension toolbox, making it possible to encode two dimensions within a large atomic spin. The protocol combines first- and second-order spin couplings, such that the spin projection $m$ and the remainder $r=m$ (mod 3) of its Euclidian division by 3 act as orthogonal coordinates on a synthetic cylinder. It is suited for an implementation with lanthanide atoms, which feature a large electronic spin and narrow optical transitions for applying the required spin couplings. This method is useful for simulating geometries with periodic boundary conditions, and engineering various types of topological systems evolving in high dimensions.

cond-mat.quant-gas↗

arXiv2021

Partitioning dysprosium's electronic spin to reveal entanglement in non-classical states

Quantum spins of mesoscopic size are a well-studied playground for engineering non-classical states. If the spin represents the collective state of an ensemble of qubits, its non-classical behavior is linked to entanglement between the qubits. In this work, we report on an experimental study of entanglement in dysprosium's electronic spin. Its ground state, of angular momentum $J=8$, can formally be viewed as a set of $2J$ qubits symmetric upon exchange. To access entanglement properties, we partition the spin by optically coupling it to an excited state $J'=J-1$, which removes a pair of qubits in a state defined by the light polarization. Starting with the well-known W and squeezed states, we extract the concurrence of qubit pairs, which quantifies their non-classical character. We also directly demonstrate entanglement between the 14- and 2-qubit subsystems via an increase in entropy upon partition. In a complementary set of experiments, we probe decoherence of a state prepared in the excited level $J'=J+1$ and interpret spontaneous emission as a loss of a qubit pair in a random state. This allows us to contrast the robustness of pairwise entanglement of the W state with the fragility of the coherence involved in a Schrödinger cat state. Our findings open up the possibility to engineer novel types of entangled atomic ensembles, in which entanglement occurs within each atom's electronic spin as well as between different atoms.

quant-ph↗

arXiv2021

Probing chiral edge dynamics and bulk topology of a synthetic Hall system

Quantum Hall systems are characterized by the quantization of the Hall conductance -- a bulk property rooted in the topological structure of the underlying quantum states. In condensed matter devices, material imperfections hinder a direct connection to simple topological models. Artificial systems, such as photonic platforms or cold atomic gases, open novel possibilities by enabling specific probes of topology or flexible manipulation e.g. using synthetic dimensions. However, the relevance of topological properties requires the notion of a bulk, which was missing in previous works using synthetic dimensions of limited sizes. Here, we realize a quantum Hall system using ultracold dysprosium atoms, in a two-dimensional geometry formed by one spatial dimension and one synthetic dimension encoded in the atomic spin $J=8$. We demonstrate that the large number of magnetic sublevels leads to distinct bulk and edge behaviors. Furthermore, we measure the Hall drift and reconstruct the local Chern marker, an observable that has remained, so far, experimentally inaccessible. In the center of the synthetic dimension -- a bulk of 11 states out of 17 -- the Chern marker reaches 98(5)\% of the quantized value expected for a topological system. Our findings pave the way towards the realization of topological many-body phases.

cond-mat.quant-gas↗

arXiv2019

Probing quantum criticality and symmetry breaking at the microscopic level

We report on an experimental study of the Lipkin-Meshkov-Glick model of quantum spins interacting at infinite range in a transverse magnetic field, which exhibits a ferromagnetic phase transition in the thermodynamic limit. We use Dysprosium atoms of electronic spin $J=8$, subjected to a quadratic Zeeman light shift, to simulate $2J=16$ interacting spins $1/2$. We probe the system microscopically using single magnetic sublevel resolution, giving access to the spin projection parity, which is the collective observable characterizing the underlying $\mathbb{Z}_2$ symmetry. We measure the thermodynamic properties and dynamical response of the system, and study the quantum critical behavior around the transition point. In the ferromagnetic phase, we achieve coherent tunneling between symmetry-broken states, and test the link between symmetry breaking and the appearance of a finite order parameter.

cond-mat.quant-gas↗