Array Of Atoms Research Articles

Fractional Quantum Anomalous Hall Phase for Raman Superarray of Rydberg Atoms

AbstractRydberg atom arrays offer promising platforms for quantum simulation of correlated quantum matter and raise great interests. This work proposes a novel stripe‐lattice model with “Raman superarray of Rydberg atoms” to realize bosonic fractional quantum anomalous Hall (FQAH) phase. Two types of Rydberg states, arranged in a supperarray configuration and with Raman‐assisted dipole‐exchange couplings, are implemented to realize a minimal QAH model for hard‐core bosons populated into a topological flat band with large bulk gap under proper tunable experimental condition. With this the bosonic FQAH phase can be further achieved and probed feasibly. In particular, a novel quench protocol is proposed to probe the fractionalized excitations by measuring the correlated quench dynamics featured by fractional charge tunneling between bulk and chiral edge modes in the open boundary.

Tunable Quantum Criticality in Multicomponent Rydberg Arrays.

Arrays of Rydberg atoms have appeared as a remarkably rich playground to study quantum phase transitions in one dimension. One of the biggest puzzles that was brought forward in this context are chiral phase transitions out of density waves. Theoretically predicted chiral transition out of period-four phase is still pending experimental verification mainly due to extremely short interval over which this transition is realized in a single-component Rydberg array. In this Letter, we show that multicomponent Rydberg arrays with extra experimentally tunable parameters provide a mechanism to manipulate quantum critical properties without breaking translation symmetry explicitly. We consider an effective blockade model of two component Rydberg atoms. Weak and strong components obey nearest- and next-nearest-neighbor blockades correspondingly. When laser detuning is applied to either of the two components the system is in the period-3 and period-2 phases. But laser detuning applied to both components simultaneously stabilizes the period-4 phase partly bounded by the chiral transition. We show that relative ratio of the Rabi frequencies of the two components tunes the properties of the conformal Ashkin-Teller point and allows us to manipulate an extent of the chiral transition. The prospects of multicomponent Rydberg arrays in the context of critical fusion is briefly discussed.

Controlled Growth of Metal Atom Arrays on Graphdiyne for Seawater Oxidation.

Advanced atomic-level heterointerface engineering provides a promising method for the preparation of next-generation catalysts. Traditional carbon-based heterointerface catalytic performance rely heavily on the undetermined defects in complex and demanding preparation processes, rendering it impossible to control the catalytic performance. Here, we present a general method for the controlled growth of metal atom arrays on graphdiyne (GDY/IrCuOx), and we are surprised to find strong heterointerface strains during the growth. We successfully controlled the thickness of GDY to regulate the heterointerface metal atoms and achieved compressive strain at the interface. Experimental and density functional theory calculation results show that the unique incomplete charge transfer between GDY and metal atoms leads to the formation of strong interactions and significant heterointerface compressive strain between GDY and IrCuOx, which results in high oxidation performances with 1000 mA cm-2 at a low overpotential of 283 mV and long-term stability at large current densities in alkaline simulated seawater. We anticipate that this finding will contribute to construction of high-performance heterogeneous interface structures, leading to the development of new generation of GDY-based heterojunction catalysts in the field of catalysis for future promising performance.

Thermoelectric performance optimization of GeMnSbTe compounds through increasing the Mn solid solubility: Effects of the co-doping of rare earth elements

GeTe is a p-type thermoelectric (TE) material that exhibits a high ZT value and holds promise for a wide range of applications. In this study, a series of Ge0.86Mn0.1Sb0.04Te + 1 mol.% RE (Rare Earth elements = Er, Tm, Yb, Lu) compounds are synthesized through the melt-quenching method followed by fast-hot-pressing. Findings indicate that the TE properties are improved by simultaneously increasing the Seebeck coefficient and reducing the thermal conductivity, making the peak ZT value experiences an enhancement of 73%, while the average ZT value through 450–800 K shows an improvement of 70%. The solid solubility of Mn is significantly increased by the addition of the REs, that promotes the regulating effect of Mn on the energy band. A diverse range of microstructures including ordered atomic staggered arrays, van der Waals interstitials, dislocation enrichment, dislocation networks, nano precipitation phases with cavity structures, interstitial clusters, and vacancy clusters are introduced by REs, significantly contributing to the reduction of the κL. Thus, this study offers valuable insights and mechanism analysis into enhancing the properties of GeMnSbTe materials by incorporating REs, and proves that Tm has better thermoelectric performance optimization effect in this.

Observation of millihertz-level cooperative Lamb shifts in an optical atomic clock.

Collective couplings of atomic dipoles to a shared electromagnetic environment produce a wide range of many-body phenomena. We report on the direct observation of resonant electric dipole-dipole interactions in a cubic array of atoms in the many-excitation limit. The interactions produce spatially dependent cooperative Lamb shifts when spectroscopically interrogating the millihertz-wide optical clock transition in strontium-87. We show that the ensemble-averaged shifts can be suppressed below the level of evaluated systematic uncertainties for optical atomic clocks. Additionally, we demonstrate that excitation of the atomic dipoles near a Bragg angle can enhance these effects by nearly an order of magnitude compared with nonresonant geometries. Our work demonstrates a platform for precise studies of the quantum many-body physics of spins with long-range interactions mediated by propagating photons.

Modifying cooperative decay via disorder in atom arrays

Modifying cooperative decay via disorder in atom arrays

Universal electronic descriptors for optimizing hydrogen evolution in transition metal-doped MXenes

The integration of transition metal (TM) atoms into two-dimensional (2D) transition metal carbides and nitrides (MXenes) has been identified as a promising strategy for enhancing hydrogen evolution reaction (HER) performance. However, the vast combinatorial space presents challenges for rapid catalyst screening. In response, high-throughput calculations were conducted on Ti2CO2 and Zr2CO2 doped with a wide array of TM single atoms. The local structural and corresponding electronic structural changes were analyzed, with an emphasis on their implications for HER performance. Furthermore, universal electronic descriptors were developed using the Sure Independence Screening and Sparsifying Operator (SISSO) method, harmonizing the Gibbs free energy of hydrogen adsorption (ΔGH*) trends across different MXenes substrates doped with TM atoms. These descriptors enabled the prediction of Cr, Fe, Ru, Pd, Os, and Ir as effective dopants for optimizing the ΔGH* of Hf2CO2, resulting in a reduction of ΔGH* from 1.082 eV to within ±0.2 eV. Our work not only highlights the potential of these TM dopants in significantly enhancing the catalytic activity of MXenes but also underscores the value of universal electronic structure descriptors in rapidly identifying and developing high-performance HER catalysts.

Quantum computing with subwavelength atomic arrays

Quantum computing with subwavelength atomic arrays

Measuring Nonlocal Brane Order with Error-Corrected Quantum Gas Microscopes

Exotic quantum many-body states, such as Haldane and spin liquid phases, can exhibit remarkable features like fractional excitations and non-Abelian statistics and offer new understandings of quantum entanglement in many-body quantum systems. These phases are classified by nonlocal correlators that can be directly measured in atomic analog quantum simulating platforms, such as optical lattices and Rydberg atom arrays. However, characterizing these phases in large systems is experimentally challenging because they are sensitive to local errors like atom loss, which suppress its signals exponentially. Additionally, protocols for systematically identifying and mitigating uncorrelated errors in analog quantum simulators are lacking. Here, we address these challenges by developing an error-correction method for large-scale neutral atom quantum simulators using optical lattices. Our error-correction method can distinguish correlated particle-hole pairs from uncorrelated holes in the Mott insulator. After removing the uncorrelated errors, we observe a dramatic improvement in the nonlocal parity correlator and find the perimeter scaling law. Furthermore, the error model provides a statistical estimation of fluctuations in site occupation, from which we measure the generalized brane correlator and confirm that it can be an order parameter for Mott insulators in two dimensions. Our work provides a promising avenue for investigating and characterizing exotic phases of matters in large-scale quantum simulators. Published by the American Physical Society 2024

One-dimensional single atom arrays on ferroelectric nanosheets for enhanced CO2 photoreduction

Single-atom catalysts show excellent catalytic performance because of their coordination environments and electronic configurations. However, controllable regulation of single-atom permutations still faces challenges. Herein, we demonstrate that a polarization electric field regulates single atom permutations and forms periodic one-dimensional Au single-atom arrays on ferroelectric Bi4Ti3O12 nanosheets. The Au single-atom arrays greatly lower the Gibbs free energy for CO2 conversion via Au-O=C=O-Au dual-site adsorption compared to that for Au-O=C=O single-site adsorption on Au isolated single atoms. Additionally, the Au single-atom arrays suppress the depolarization of Bi4Ti3O12, so it maintains a stronger driving force for separation and transfer of photogenerated charges. Thus, Bi4Ti3O12 with Au single-atom arrays exhibit an efficient CO production rate of 34.15 µmol·g−1·h−1, ∼18 times higher than that of pristine Bi4Ti3O12. More importantly, the polarization electric field proves to be a general tactic for the syntheses of one-dimensional Pt, Ag, Fe, Co and Ni single-atom arrays on the Bi4Ti3O12 surface.

Error-robust quantum signal processing using Rydberg atoms

Rydberg atom arrays have recently emerged as one of the most promising platforms for quantum simulation and quantum information processing. However, as is the case for other experimental platforms, the longer-term success of the Rydberg atom arrays in implementing quantum algorithms depends crucially on their robustness to gate-induced errors. Here we show that, for an idealized biased-error model based on Rydberg atom dynamics, the implementation of quantum signal processing (QSP) protocols can be made error robust, in the sense that the asymptotic scaling of the gate-induced error probability is slower than that of gate complexity. Moreover, our numerical results that use experimentally accessible parameters indicate that QSP iterates made out of more than 100 gates can be implemented with constant error probability. To showcase our approach, we provide a concrete blueprint to implement QSP-based near-optimal Hamiltonian simulation on the Rydberg atom platform. The proposed protocol substantially improves both the scaling and the overhead of gate-induced errors in comparison to those protocols that implement a fourth-order product formula. Published by the American Physical Society 2024

Experimental realization of one-dimensional single-atom array based on microscale optical dipole traps

Neutral atom array serves as a crucial experimental platform for studying many-body physics, quantum computing, and quantum simulation. In this work, we describe in detail the experimental process of preparing a one-dimensional homogeneous single atom array containing 40 Cs atoms, including the dipole trap array generation device, atomic array fluorescence imaging, and the uniformity optimization of the dipole trap array. The beam waist of the dipole trap is about 1.8 μm, and the spatial resolution of the imaging system is higher than 1.55 μm. The non-uniformity of dipole trap array is mainly caused by the intermodulation effect of multi-tone signal during amplification. The uniformity of the dipole trap array is optimized to 2% (Fig. (a)) by measuring the fluctuations of the dipole trap intensity and the light shift of trapped atom, and providing feedback to adjust the phase and amplitude applied to the multi-tone RF signal on acousto-optic deflectors. Furthermore, the uniformity of oscillation frequency, loading rate, and lifetime for trapped atom in the dipole trap array are measured. These results show that oscillation frequency has a uniformity within 2% (Fig. (b)); mean loading rate is around 58% with a uniformity within 3%; and mean lifetime of single atom in dark trap is around 6(1) s with a uniformity within 8%.

Superradiant and Subradiant Cavity Scattering by Atom Arrays.

We realize collective enhancement and suppression of light scattered by an array of tweezer-trapped ^{87}Rb atoms positioned within a strongly coupled Fabry-Pérot optical cavity. We illuminate the array with light directed transverse to the cavity axis, in the low saturation regime, and detect photons scattered into the cavity. For an array with integer-optical-wavelength spacing each atom scatters light into the cavity with nearly identical scattering amplitude, leading to an observed N^{2} scaling of cavity photon number as the atom number increases stepwise from N=1 to N=8. By contrast, for an array with half-integer-wavelength spacing, destructive interference of scattering amplitudes yields a nonmonotonic, subradiant cavity intensity versus N. By analyzing the polarization of light emitted from the cavity, we find that Rayleigh scattering can be collectively enhanced or suppressed with respect to Raman scattering. We observe also that atom-induced shifts and broadenings of the cavity resonance are precisely tuned by varying the atom number and positions. Altogether, tweezer arrays provide exquisite control of atomic cavity QED spanning from the single- to the many-body regime.

Artificial Atoms, Wigner Molecules, and an Emergent Kagome Lattice in Semiconductor Moiré Superlattices.

Semiconductor moiré superlattices comprise an array of artificial atoms and provide a highly tunable platform for exploring novel electronic phases. We introduce a theoretical framework for studying moiré quantum matter that treats intra-moiré-atom interactions exactly and is controlled in the limit of large moiré period. We reveal an abundance of new physics arising from strong electron interactions when there are multiple electrons within a moiré unit cell. In particular, at filling factor n=3, the Coulomb interaction within each three-electron moiré atom leads to a three-lobed "Wigner molecule." When their size is comparable to the moiré period, the Wigner molecules form an emergent Kagome lattice. Our Letter identifies two universal length scales characterizing the kinetic and interaction energies in moiré materials and demonstrates a rich phase diagram due to their interplay.

Trimer quantum spin liquid in a honeycomb array of Rydberg atoms

Quantum spin liquids are elusive but paradigmatic examples of strongly correlated quantum states that are characterized by long-range quantum entanglement. Recently, signatures of a gapped topological Z2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\mathbb{Z}}}_{2}$$\\end{document} spin liquid have been observed in a system of Rydberg atoms; however, the full capability of these platforms to realize quantum spin liquids extends far beyond this state alone. Here, we propose the realization of a different class of spin liquids in a honeycomb array of Rydberg atoms. Exploring the system’s quantum phase diagram using density-matrix renormalization group and exact diagonalization calculations, we identify several density-wave-ordered phases and a trimer spin liquid ground state with an emergent U(1) × U(1) local symmetry. This liquid state originates from superpositions of classical trimer configurations on the dual triangular lattice in the regime where third-nearest-neighbor atoms lie within the Rydberg blockade radius. Finally, we discuss the conditions to enhance the preparation fidelity of this state by a general Rydberg-blockade-based projection mechanism, test the robustness of the trimer spin liquid phase in a range of realistic parameters, and outline methods for its experimental detection.

Collective radiative interactions in the discrete truncated Wigner approximation

Interfaces of light and matter serve as a platform for exciting many-body physics and photonic quantum technologies. Due to the recent experimental realization of atomic arrays at sub-wavelength spacings, collective interaction effects such as superradiance have regained substantial interest. Their analytical and numerical treatment is however quite challenging. Here we develop a semiclassical approach to this problem that allows to describe the coherent and dissipative many-body dynamics of interacting spins while taking into account lowest-order quantum fluctuations. For this purpose we extend the discrete truncated Wigner approximation, originally developed for unitarily coupled spins, to include collective, dissipative spin processes by means of truncated correspondence rules. This maps the dynamics of the atomic ensemble onto a set of semiclassical, numerically inexpensive stochastic differential equations. We benchmark our method with exact results for the case of Dicke decay, which shows excellent agreement. For small arrays we compare to exact simulations, again showing good agreement at early times and at moderate to strong driving, and to a second order cumulant expansion. We conclude by studying the radiative properties of a spatially extended three-dimensional, coherently driven gas and compare the coherence of the emitted light to experimental results.

Logical quantum processor based on reconfigurable atom arrays

Suppressing errors is the central challenge for useful quantum computing1, requiring quantum error correction (QEC)2–6 for large-scale processing. However, the overhead in the realization of error-corrected ‘logical’ qubits, in which information is encoded across many physical qubits for redundancy2–4, poses substantial challenges to large-scale logical quantum computing. Here we report the realization of a programmable quantum processor based on encoded logical qubits operating with up to 280 physical qubits. Using logical-level control and a zoned architecture in reconfigurable neutral-atom arrays7, our system combines high two-qubit gate fidelities8, arbitrary connectivity7,9, as well as fully programmable single-qubit rotations and mid-circuit readout10–15. Operating this logical processor with various types of encoding, we demonstrate improvement of a two-qubit logic gate by scaling surface-code6 distance from d = 3 to d = 7, preparation of colour-code qubits with break-even fidelities5, fault-tolerant creation of logical Greenberger–Horne–Zeilinger (GHZ) states and feedforward entanglement teleportation, as well as operation of 40 colour-code qubits. Finally, using 3D [[8,3,2]] code blocks16,17, we realize computationally complex sampling circuits18 with up to 48 logical qubits entangled with hypercube connectivity19 with 228 logical two-qubit gates and 48 logical CCZ gates20. We find that this logical encoding substantially improves algorithmic performance with error detection, outperforming physical-qubit fidelities at both cross-entropy benchmarking and quantum simulations of fast scrambling21,22. These results herald the advent of early error-corrected quantum computation and chart a path towards large-scale logical processors.

Tracking a nonrelativistic charge with an array of Rydberg atoms

Tracking a nonrelativistic charge with an array of Rydberg atoms

Midcircuit Operations in Atomic Arrays

Midcircuit Operations in Atomic Arrays

Erratum: Spontaneous symmetry breaking in frustrated triangular atom arrays due to cooperative light scattering [Phys. Rev. Research 4 , 043039 (2022)

Erratum: Spontaneous symmetry breaking in frustrated triangular atom arrays due to cooperative light scattering [Phys. Rev. Research <b>4</b> , 043039 (2022)