Mesoscopic Rydberg-blockaded ensembles in the superatom regime and beyond

Abstract

Controlling strongly interacting many-body systems enables the creation of tailored quantum matter, with properties transcending those based solely on single particle physics. Atomic ensembles which are optically driven to a Rydberg state provide many examples of this, such as atom-atom entanglement [1,2], many-body Rabi oscillations [3], strong photon-photon interaction [4] and spatial pair correlations [5]. In its most basic form, Rydberg quantum matter consists of an isolated ensemble of strongly interacting atoms spatially confined to the blockade volume -a so-called superatom. Here we demonstrate the controlled creation and characterization of an isolated mesoscopic superatom by means of accurate density engineering and excitation to Rydberg p-states. Its variable size allows to investigate the transition from effective two-level physics for strong confinement to many-body phenomena in extended systems. By monitoring continuous laser-induced ionization we observe a strongly anti-bunched ion emission under blockade conditions and extremely bunched ion emission under off-resonant excitation. Our experimental setup enables in vivo measurements of the superatom, yielding insight into both excitation statistics and dynamics. We anticipate straightforward applications in quantum optics and quantum information as well as future experiments on many-body physics.Rydberg superatoms combine single and many-body quantum effects in a unique way and have been proposed as fundamental building blocks for quantum simulation and quantum information [6]. Due to the phenomenon of Rydberg blockade [7], the ensemble collectively forms a system with only two levels of excitation. Provided a range of interaction larger than the sample size, the presence of one excitation shifts all other atoms out of resonance and therefore only one excitation can be created at a time. Changing the size or the driving conditions revives the underlying many-body nature and the presence of several excited atoms with pronounced correlations becomes possible. This tunability and the possibility of multiple usage within a single experimental sequence make superatoms a promising complement to single-atom-based quantum technology. It is therefore important to understand the significance of the superatom concept, the implications of its finite spatial extent and its many-body level structure. We here investigate the latter by measuring the mean Rydberg excitation as well as its time-resolved two-particle correlations in an optically excited, mesoscopic superatom for varying excitation strength and under resonant and non-resonant conditions, revealing very different excitation dynamics.The realization of superatom-based quantum systems requires the implementation of arbitrary arrangements of isolated mesoscopic atomic ensembles in a scalable way. We here prepare an individual superatom by carefully shaping the density distribution of a Bose-Einstein condensate of 87 Rb atoms. We first load the condensate into a one-dimensional optical lattice with a spacin...

Self-similar nonequilibrium dynamics of a many-body system with power-law interactions

“…Moreover, we show that the relaxation dynamics crosses over into a mean-field regime when the power-law exponent becomes equal to the system dimension. Beyond providing an understanding of non-equilibrium processes governed by power-law interactions our results reveal new insights into the relaxation behavior of gases of interacting Rydberg atoms, which are currently widely employed for the experimental study of many-body phenomena [10][11][12][13][14][15][16]. Our results indicate that the characteristic minimal distance between Rydberg excitations -which is often referred to as blockade radius -is not generally a static quantity but can in the presence of dissipation acquire a non-trivial scale-invariant time-dependence.…”

Interaction Enhanced Imaging of Rydberg P states

“…Nevertheless, the detection efficiency is limited to ≤ 50% by the quantum efficiency of the MCP. Using this technique, spatial correlations through the pair correlation function and van der Waals interactions between Rydberg atoms have been measured [17][18][19][20].…”

Implementation of chiral quantum optics with Rydberg and trapped-ion setups

“…Moreover, our model considers the so-called 'frozen regime' [57], where the motion of untrapped Rydberg atoms is neglected. The underlying assumption of this regime, which describes Rydberg experiments [38][39][40][41][42] performed in the micro-second regime, are twofold. First, the forces associated with the dipoledipole interactions are sufficiently weak to maintain the atoms in their original position for the time of the experiment.…”

“…In this section, we present a physical implementation of a chiral network whose waveguide is made of spins using an array of (alkali) Rydberg atoms, which can be realized with optical lattices [38,39], tweezers [40][41][42][43] or magnetic traps [44,45]. To obtain the synthetic gauge field required for the realization of the chiral coupling, we exploit the 'spin-orbit properties' naturally present in Rydberg dipole-dipole interactions [46][47][48].…”