arXiv subjects

Roee Ozeri

Publications and source records attributed to Roee Ozeri.

At least 19 recordsLinked to original sources

arXiv2026

A Quantum Interface Between Neutral-Atoms and Trapped-Ions Quantum Registers

Hybrid quantum systems combining neutral atoms and trapped ions offer the prospect of integrating the scalability of atom arrays with the high-fidelity control available in trapped-ion platforms. Here we propose and analyze a quantum interface between individually trapped neutral atoms and a trapped-ion crystal. In our scheme, a neutral 88Sr atom trapped in optical tweezers interacts with a small 88Sr+ ion crystal, and by exciting the atom to a Rydberg state, the atom-ion polarization interaction is strongly enhanced, resulting in a state-dependent modification of the ions' collective motional modes. We show that this shift enables conditional control of a MS gate, allowing the neutral atom to act as a control qubit for an entangling operation between two ions. We investigate the feasibility of the scheme by analyzing Rydberg trapping in the combined optical tweezers and Paul trap potentials, identifying negative-polarizability Rydberg states as particularly favorable for stable confinement. We further evaluate the relevant trapping conditions, Rydberg lifetimes, and coherence requirements, and show that the proposed interface is compatible with realistic experimental parameters. These results establish a practical route toward deterministic atom-ion hybrid quantum gates and quantum interfaces.

quant-ph↗

arXiv2026

Trapped-Ion Multiqubit Gates are Compatible with Scalable Quantum Error Correction

We construct a detailed microscopic noise model for multi-qubit (MQ) gate operations in the context of trapped ion architecture with all-to-all connectivity. We find that phonon heating and motional dephasing are well captured by effective single- and two-qubit error channels that can, in principle, act between arbitrary pairs of qubits. Nevertheless, the median magnitude of two-qubit errors between uncoupled qubits is substantially smaller than that of errors between gate-coupled qubits. Errors associated with photon scattering are shown to solely propagate to qubits participating in gate operations. Lastly, we combine all noise sources, assigned with experimentally relevant parameters, and explore the scalability of a quantum error correction (QEC) scheme based on the rotated surface code, as a function of error rates and code size. Our analysis bridges device-level physics and QEC performance for MQ gates in trapped-ion architectures.

quant-ph↗

arXiv2026

Digital Predistortion of Optical Fields for Fast and High-Fidelity Entangling Gates in Trapped-Ion Qubits

High-fidelity quantum gates require precise classical control signals, yet the analog hardware delivering these signals introduces nonlinear distortions that degrade gate performance. We demonstrate digital predistortion of an acousto-optic modulator used to generate multi-tone entangling-gate waveforms in a trapped-ion processor based on $^{88}$Sr$^+$. By measuring and inverting the static nonlinear amplitude response of the modulator, we apply a feed-forward correction that extends its linear operating range and suppresses spurious intermodulation products. Spectral analysis of the gate beam shows 3--5 dB suppression of the dominant intermodulation tones, approximately doubling the usable diffraction efficiency at a $10^{-3}$ estimated gate-error threshold. Direct two-qubit Bell-state fidelity measurements confirm that predistortion consistently improves entangling-gate performance. The calibrate-and-invert methodology is device and platform agnostic, applicable to any nonlinear element in the classical control chain of a quantum processor.

quant-ph↗

arXiv2026

Direct comparison of multi-ion optical clocks based on $^{40}$Ca$^+$ and $^{88}$Sr$^+$

We report the first direct frequency comparison between two multi-ion optical clocks based on the S$_{1/2}$ to D$_{5/2}$ transition in \Ca and \Sr ions. Using linear chains of up to nine \Ca ions and six \Sr ions, we demonstrate improved stability as a function of the number of ions that are contributing to the laser frequency stabilization servo. The measured joint fractional frequency stability of the two clocks reaches $1.37(12)\times 10^{-15}$ at one second, placing an upper bound on the same stability of one of the clocks at $9.6(8)\times 10^{-16}$ in one second. We measured the frequency ratio of the two clocks to be $R_{\text{Sr/Ca}}=1.082076536381896986(18)$, where the systematic uncertainty is primarily limited by the room temperature blackbody radiation. Our direct measurement represents an order of magnitude improvement compared to existing indirect frequency ratio measurements. Furthermore, by combining our results with recent absolute frequency measurements of the \Sr transition, referenced to a primary frequency standard, we refined the absolute frequency of the \Ca transition to $\nu_{\text{Ca}^+}=411042129776400.21(4)$ Hz, reducing its uncertainty by a factor of three. This study presents the first direct comparison between two multi-ion optical clocks, highlighting their significant potential for future applications in fundamental physics tests, geodesy, and precision metrology.

physics.atom-ph↗

arXiv2025

Optical tweezer-controlled entanglement gates with trapped ion qubits

We propose an entanglement protocol where ions illuminated by optical tweezers serve as control qubits. We experimentally demonstrate this proposal with a controlled M$\o$lmer-S$\o$rensen operation on a three-ion chain, analogous to the canonical Toffoli gate. Our demonstration features cases in which the control qubit was in one of its logical basis states, and not in their superposition, due to dephasing by tweezer beam intensity fluctuations. Finally, we discuss how our protocol generalizes to a broad class of unitary operations and larger qubit systems, enabling a single-pulse implementation of $n$-controlled unitaries.

quant-ph↗

arXiv2025

Probing New Forces with Nuclear Clocks

Clocks based on nuclear isomer transitions promise exceptional stability and precision. The low transition energy of the thorium-229 isomer makes it an ideal candidate, as it has been excited by a vacuum-ultraviolet laser and is highly sensitive to subtle interactions. This enables the development of powerful tools for probing new forces, which we call {\it quintessometers}. In this work, we demonstrate the potential of nuclear clocks, particularly solid-state variants, to surpass existing limits on scalar field couplings, exceeding the sensitivity of current fifth-force searches at submicron distances and significantly improving equivalence-principle tests at kilometer scales and beyond. Additionally, we highlight the capability of transportable nuclear clocks to detect scalar interactions at distances beyond $10\,$km, complementing space-based missions.

hep-ph↗

arXiv2024

Operating a multi-ion clock with dynamical decoupling

We study and characterize a quasi-continuous dynamical decoupling (QCDD) scheme that effectively suppresses dominant frequency shifts in a multi-ion optical clock. Addressing the challenge of inhomogeneous frequency shifts in such systems, our scheme mitigates primary contributors, namely the electric quadrupole shift (QPS) and the linear Zeeman shift (LZS). Based on $^{88}$Sr$^+$ ions, we implement a QCDD scheme in linear chains of up to 7 ions and demonstrate a significant suppression of the shift by more than three orders of magnitude, leading to relative frequency inhomogeneity below $7\cdot10^{-17}$. Additionally, we evaluate the associated systematic shift arising from the radiofrequency (RF) drive used in the QCDD scheme, showing that, in the presented realization, its contribution to the systematic relative frequency uncertainty is below $10^{-17}$, with potential for further improvement. These results provide a promising avenue toward implementing multi-ion clocks exhibiting an order of magnitude or more improvement in stability while maintaining a similar high degree of accuracy to that of single-ion clocks.

physics.atom-ph↗

arXiv2024

Quantum control of ion-atom collisions beyond the ultracold regime

Tunable scattering resonances are crucial for controlling atomic and molecular systems. However, their use has so far been limited to ultracold temperatures. These conditions remain hard to achieve for most hybrid trapped ion-atom systems -- a prospective platform for quantum technologies and fundamental research. Here we measure inelastic collision probabilities for ${\text{Sr}^++\text{Rb}}$ and use them to calibrate a comprehensive theoretical model of ion-atom collisions. Our theoretical results, compared with experimental observations, confirm that quantum interference effects persist to the multiple-partial-wave regime, leading to the pronounced state and mass dependence of the collision rates. Using our model, we go beyond interference and identify a rich spectrum of Feshbach resonances at moderate magnetic fields with the Rb atom in its lower ($f=1$) hyperfine state, which persist at temperatures as high as 1 mK. Future observation of these predicted resonances should allow precise control of the short-range dynamics in ${\text{Sr}^+}+{\text{Rb}}$ collisions under unprecedentedly warm conditions.

physics.atom-ph↗

arXiv2024

The inverse Mpemba effect demonstrated on a single trapped ion qubit

The Mpemba effect is a counter-intuitive phenomena in which a hot system reaches a cold temperature faster than a colder system, under otherwise identical conditions. Here we propose a quantum analog of the Mpemba effect, on the simplest quantum system, a qubit. Specifically, we show it exhibits an inverse effect, in which a cold qubit reaches a hot temperature faster than a hot qubit. Furthermore, in our system a cold qubit can heat up exponentially faster, manifesting the strong version of the effect. This occurs only for sufficiently coherent systems, making this effect quantum mechanical, i.e. due to interference effects. We experimentally demonstrate our findings on a single $^{88}\text{Sr}^+$ trapped ion qubit. The existence of this anomalous relaxation effect in simple quantum systems reveals its fundamentality, and may have a role in designing and operating quantum information processing devices.

quant-ph↗

arXiv2024

Chaotic scattering in ultracold atom-ion collisions

We report on signatures of classical chaos in ultracold collisions between a trapped ion and a free atom. Using numerical simulations, we show that the scattering dynamics can be highly sensitive to initial conditions for various mass ratios and trapping frequencies, indicating the onset of chaos. We quantify this chaotic dynamics by calculating its fractal dimension. We show that for a trapped $^{88}$Sr$^+$ ion and a free $^{87}$Rb atom chaotic dynamic appears under experimentally relevant conditions, and find its characteristic energy scale. The observation of classical chaos in atom-trapped-ion collisions suggests that signatures of quantum chaos might appear, for example, through a Wigner-Dyson distribution of collisional resonances.

physics.atom-ph↗

arXiv2023

Scalable architecture for trapped-ion quantum computing using RF traps and dynamic optical potentials

Qubits based on ions trapped in linear radio-frequency traps form a successful platform for quantum computing, due to their high fidelity of operations, all-to-all connectivity and degree of local control. In principle there is no fundamental limit to the number of ion-based qubits that can be confined in a single 1D register. However, in practice there are two main issues associated with long trapped-ion crystals, that stem from the 'softening' of their modes of motion, upon scaling up: high heating rates of the ions' motion, and a dense motional spectrum; both impede the performance of high-fidelity qubit operations. Here we propose a holistic, scalable architecture for quantum computing with large ion-crystals that overcomes these issues. Our method relies on dynamically-operated optical potentials, that instantaneously segment the ion-crystal into cells of a manageable size. We show that these cells behave as nearly independent quantum registers, allowing for parallel entangling gates on all cells. The ability to reconfigure the optical potentials guarantees connectivity across the full ion-crystal, and also enables efficient mid-circuit measurements. We study the implementation of large-scale parallel multi-qubit entangling gates that operate simultaneously on all cells, and present a protocol to compensate for crosstalk errors, enabling full-scale usage of an extensively large register. We illustrate that this architecture is advantageous both for fault-tolerant digital quantum computation and for analog quantum simulations.

quant-ph↗

arXiv2023

Programmable quantum simulations on a trapped-ions quantum simulator with a global drive

Simulation of quantum systems is notoriously challenging for classical computers, while quantum hardware is naturally well-suited for this task. However, the imperfections of contemporary quantum systems poses a considerable challenge in carrying out accurate simulations over long evolution times. Here we experimentally demonstrate a method for quantum simulations on a small-scale trapped ions-based quantum simulator. Our method enables quantum simulations of programmable spin-Hamiltonians, using only simple global fields, driving all qubits homogeneously and simultaneously. We measure the evolution of a quantum Ising ring and accurately reconstruct the Hamiltonian parameters, showcasing an accurate and high-fidelity simulation. Our method enables a significant reduction in the required control and depth of quantum simulations, thus generating longer evolution times with higher accuracy.

quant-ph↗

arXiv2023

Fast design and scaling of multi-qubit gates in large-scale trapped-ion quantum computers

Quantum computers based on crystals of trapped ions are a prominent technology for quantum computation. A unique feature of trapped ions is their long-range Coulomb interactions, which can be exploited to realize large-scale multiqubit entanglement gates. However, scaling up the number of qubits, $N$, in these systems, while retaining high-fidelity and high-speed operations, is challenging. Specifically, designing multiqubit entanglement gates in long ion crystals of hundreds of ions involves an NP-hard optimization problem, rendering scale-up not only a technological challenge, but also a conceptual challenge. Here we introduce a method that mitigates this challenge, effectively allowing for a polynomial-time design of fast, robust, and programmable entanglement gates, acting on the entire ion-crystal. We show that while the number of simultaneous entanglement operations scales as $N^2$, the gate duration scales as $N$, leading to a scaling advantage. We use our methods to investigate the drive-power requirements and susceptibility to noise and errors of these multiqubit gates. Our method delineates a path towards scaling up quantum computers based on ion-crystals with hundreds of qubits.

quant-ph↗

arXiv2023

Observation of trap-assisted formation of atom-ion bound states

Pairs of free particles cannot form bound states in elastic collision due to momentum and energy conservation. In many ultracold experiments, however, the particles collide in the presence of an external trapping potential which can couple the center-of-mass and relative motions and assist the formation of bound-states. Here, we report on observation of weakly bound molecular states formed between one ultracold $^{87}$Rb atom and a single trapped $^{88}$Sr$^+$ ion in the presence of a linear Paul trap. We show that bound states can form efficiently in binary collisions, and enhance the rate of inelastic processes. By observing electronic spin-exchange rate, we study the dependence of these bound states on the collision energy and magnetic field and extract the average molecular binding energy $E_{\textrm{bind}}=0.7(1)$ mK$\cdot k_B$ and the mean lifetime of the molecule $τ=0.5(1)\,μ$s, with good agreement with molecular-dynamics simulations. Our simulations predict a highly unusual power-law distribution of molecular lifetimes with a mean that is dominated by extreme, long-lived, events. The dependence of the molecular properties on the trapping parameters opens new avenues to study and control ultracold collisions.

physics.atom-ph↗

arXiv2022

Quantum suppression of cold reactions far from the s-wave energy limit

Quantum effects in chemical reactions are most pronounced at ultracold temperatures, where only a few partial waves contribute. While interference among many partial waves is theoretically expected to persist at higher temperatures, direct evidence for such quantum effects in reactive processes has been lacking. Here, we report the first observation of quantum interference suppressing a chemical reaction in the multi-partial-wave regime: resonant charge exchange between a single $^{87}$Rb atom and its parent ion $^{87}$Rb$^+$. Using quantum-logic detection on a single atom-ion pair and a calibrated in-situ measurement of Langevin collision probabilities, we benchmark the thermally averaged reaction rate against both classical and quantum predictions. We find that the reaction rate is suppressed by over an order of magnitude relative to the classical expectation, despite occurring in the millikelvin temperature regime (more than three orders of magnitude above the $s$-wave threshold), where more than a dozen partial waves contribute. These results establish quantum interference as a key mechanism in chemical reactivity beyond the ultracold limit and offer a platform for probing coherent quantum effects in atom-ion reactions where \textit{ab initio} methods remain intractable.

quant-ph↗

arXiv2022

The effect of fast noise on the fidelity of trapped-ions quantum gates

High fidelity single and multi-qubit operations compose the backbone of quantum information processing. This fidelity is based on the ability to couple single- or two-qubit levels in an extremely coherent and precise manner. A necessary condition for coherent quantum evolution is a highly stable local oscillator driving these transitions. Here we study the effect of fast noise, that is noise at frequencies much higher than the local oscillator linewidth, on the fidelity of one- and two-qubit gates in a trapped-ion system. We analyze and measure the effect of fast noise on single qubit operations including resonant $π$ rotations and off-resonant sideband transitions . We further analyze the effect of fast phase noise on the Molmer-Sorensen two-qubit gate. We find a unified and simple way to estimate the performance of all of these operations through a single parameter given by the noise power spectral density at the qubit response frequency. While our analysis focuses on phase noise and on trapped-ion systems, it is relevant for other sources of fast noise as well as for other qubit systems in which spin-like qubits are coupled by a common bosonic field. Our analysis can help in guiding the deign of quantum hardware platforms and gates, improving their fidelity towards fault-tolerant quantum computing.

quant-ph↗

arXiv2022

Robust two-qubit trapped ions gates using spin-dependent squeezing

Entangling gates are an essential component of quantum computers. However, generating high-fidelity gates, in a scalable manner, remains a major challenge in all quantum information processing platforms. Accordingly, improving the fidelity and robustness of these gates has been a research focus in recent years. In trapped ions quantum computers, entangling gates are performed by driving the normal modes of motion of the ion chain, generating a spin-dependent force. Even though there has been significant progress in increasing the robustness and modularity of these gates, they are still sensitive to noise in the intensity of the driving field. Here we supplement the conventional spin-dependent displacement with spin-dependent squeezing, which enables a gate that is robust to deviations in the amplitude of the driving field. We solve the general Hamiltonian and engineer its spectrum analytically. We also endow our gate with other, more conventional, robustness properties, making it resilient to many practical sources of noise and inaccuracies.

quant-ph↗

arXiv2022

Quantum simulations of interacting systems with broken time-reversal symmetry

Many-body systems of quantum interacting particles in which time-reversal symmetry is broken give rise to a variety of rich collective behaviors, and are therefore a major target of research in modern physics. Quantum simulators can potentially be used to explore and understand such systems, which are often beyond the computational reach of classical simulation. Of these, platforms with universal quantum control can experimentally access a wide range of physical properties. However, simultaneously achieving strong programmable interactions, strong time-reversal symmetry breaking, and high fidelity quantum control in a scalable manner is challenging. Here we realized quantum simulations of interacting, time-reversal broken quantum systems in a universal trapped-ion quantum processor. Using a scalable scheme that was recently proposed we implemented time-reversal breaking synthetic gauge fields, shown for the first time in a trapped ion chain, along with unique coupling geometries, potentially extendable to simulation of multi dimensional systems. Our high fidelity single-site resolution in control and measurement, along with highly programmable interactions, allow us to perform full state tomography of a ground state showcasing persistent current, and to observe dynamics of a time-reversal broken system with nontrivial interactions. Our results open a path towards simulation of time-reversal broken many-body systems with a wide range of features and coupling geometries.

quant-ph↗