arXiv subjects

Ryan White

Publications and source records attributed to Ryan White.

10 recordsLinked to original sources

arXiv2026

Quantum Cellular Automata on a Dual-Species Rydberg Processor

As quantum devices scale to larger and larger sizes, a significant challenge emerges in scaling their coherent controls accordingly. Quantum cellular automata (QCAs) constitute a promising framework that bypasses this control problem: universal dynamics can be achieved using only a static qubit array and global control operations. Despite an extensive history of theoretical explorations and proposals, QCAs have not been experimentally explored in the context of highly-scalable globally-controlled systems. Here we realize QCAs on a dual-species Rydberg array of rubidium and cesium atoms, leveraging independent global control of each species to perform multiple quantum protocols. Seeding an automaton with different initial states, we explore many-body dynamics of quasiparticles and grow GHZ states across both species, highlighting the flexibility of our approach. We further develop a second automaton using a novel mediated entangling gate, enabling generation of 96.7(1.7)%-fidelity Bell states, 17-qubit cluster states, and high-connectivity graph states. Our results demonstrate that simple global controls enable access to a rich variety of applications through the QCA framework. The versatility and scalability of QCAs present compelling opportunities for the development of quantum information systems, as well as new perspectives on quantum many-body dynamics.

quant-ph↗

arXiv2025

Efficient Entanglement Purification Circuit Design for Dual-Species Atom Arrays

Entanglement purification protocols (EPPs) are essential for generating high-fidelity entangled states in noisy quantum systems, enabling robust quantum networking and computation. Building on the circuit of the foundational recurrence protocol, we generalize two-way EPPs to arbitrary stabilizer codes. Through analytical derivations and noisy circuit simulations incorporating circuit-level noise, we demonstrate enhanced purification performance, with fidelity improvements and finite distillation rates for distillable input states. We propose efficient circuit designs for EPPs tailored to dual-species Rydberg atom arrays, leveraging species-specific laser control and interspecies Rydberg interactions. Introducing a low-overhead operation set, the dual-species atom convenient operation set, we facilitate straightforward compilation of EPP circuits without the need for ancillary atoms or complex atom rearrangements. Our framework provides practical guidance for near-term implementations on dual-species platforms, advancing towards scalable entanglement distribution in neutral atom systems and paving the way for fault-tolerant quantum technologies.

quant-ph↗

arXiv2025

Deterministic high-rate entanglement distillation with neutral atom arrays

The goal of an entanglement distillation protocol is to convert large quantities of noisy entangled states into a smaller number of high-fidelity Bell pairs. The celebrated one-way hashing method is one such protocol, and it is known for being able to efficiently and deterministically distill entanglement in the asymptotic limit, i.e., when the size of the quantum system is very large. In this work, we consider setups with finite resources, e.g., a small fixed number of atoms in an atom array, and derive lower bounds on the distillation rate for the one-way hashing method. We provide analytical as well as numerical bounds on its entanglement distillation rate -- both significantly tighter than previously known bounds. We then show how the one-way hashing method can be efficiently implemented with neutral atom arrays. The combination of our theoretical results and the experimental blueprint we provide indicate that a full coherent implementation of the one-way hashing method is within reach with state-of-the-art quantum technology.

quant-ph↗

arXiv2024

A dual-species Rydberg array

Rydberg atom arrays have emerged as a leading platform for quantum information science. Reaching system sizes of hundreds of long-lived qubits, these arrays are used for highly coherent analog quantum simulation, as well as digital quantum computation. Advanced quantum protocols such as quantum error correction, however, require midcircuit qubit operations, including the replenishment, reset, and readout of a subset of qubits. A compelling strategy to achieve these capabilities is a dual-species architecture in which a second atomic species can be controlled without crosstalk, and entangled with the first via Rydberg interactions. Here, we realize a dual-species Rydberg array consisting of rubidium (Rb) and cesium (Cs) atoms, and explore new regimes of interactions and dynamics not accessible in single-species architectures. We achieve enhanced interspecies interactions by electrically tuning the Rydberg states close to a Forster resonance. In this regime, we demonstrate interspecies Rydberg blockade and implement quantum state transfer from one species to another. We then generate a Bell state between Rb and Cs hyperfine qubits via an interspecies controlled-phase gate. Finally, we combine interspecies entanglement with native midcircuit readout to achieve quantum non-demolition measurement of a Rb qubit using an auxiliary Cs qubit. The techniques demonstrated here pave the way toward scalable measurement-based protocols and real-time feedback control in large-scale quantum systems.

quant-ph↗

arXiv2023

A Two-dimensional Numerical Study of Ion-Acoustic Turbulence

We investigate the linear and nonlinear evolution of the ion-acoustic instability in a collisionless plasma via two-dimensional (2D2V) Vlasov-Poisson numerical simulations. We initialize the system in a stable state and gradually drive it towards instability with an imposed, weak external electric field, thus avoiding super-critical initial conditions that are physically unrealizable. The nonlinear evolution of ion-acoustic turbulence (IAT) is characterized in detail, including the particles' distribution functions, particle heating, (two-dimensional) wave spectrum, and the resulting anomalous resistivity. An important result is that no steady saturated nonlinear state is ever reached in our simulations: strong ion heating suppresses the instability, which implies that the anomalous resistivity associated with IAT is transient and short-lived. Electron-acoustic waves (EAWs) are triggered during the late nonlinear evolution of the system, caused by strong modifications to the particle distribution induced by IAT.

physics.plasm-ph↗

arXiv2023

Circuit decompositions and scheduling for neutral atom devices with limited local addressability

Despite major ongoing advancements in neutral atom hardware technology, there remains limited work in systems-level software tailored to overcoming the challenges of neutral atom quantum computers. In particular, most current neutral atom architectures do not natively support local addressing of single-qubit rotations about an axis in the xy-plane of the Bloch sphere. Instead, these are executed via global beams applied simultaneously to all qubits. While previous neutral atom experimental work has used straightforward synthesis methods to convert short sequences of operations into this native gate set, these methods cannot be incorporated into a systems-level framework nor applied to entire circuits without imposing impractical amounts of serialization. Without sufficient compiler optimizations, decompositions involving global gates will significantly increase circuit depth, gate count, and accumulation of errors. No prior compiler work has addressed this, and adapting existing compilers to solve this problem is nontrivial. In this paper, we present an optimized compiler pipeline that translates an input circuit from an arbitrary gate set into a realistic neutral atom native gate set containing global gates. We focus on decomposition and scheduling passes that minimize the final circuit's global gate count and total global rotation amount. As we show, these costs contribute the most to the circuit's duration and overall error, relative to costs incurred by other gate types. Compared to the unoptimized version of our compiler pipeline, minimizing global gate costs gives up to 4.77x speedup in circuit duration. Compared to the closest prior existing work, we achieve up to 53.8x speedup. For large circuits, we observe a few orders of magnitude improvement in circuit fidelities.

quant-ph↗

arXiv2023

Synergy Between Excluded Volume Effect with Co-embedded Microparticles and Chemical Doping in Carbon Nanotube Network-based Composites to Enhance Thermoelectric Power Factor

There is a growing momentum in recent thermoelectric materials research for flexible materials which enhance power output and efficiency at human wearable temperatures. In our previous work, we established the method to improve thermoelectric properties with co-embedding microparticles in carbon nanotube (CNT) network-based composites. In this work, we investigate the synergy of excluded volume effect by silica microparticles with CNT doping toward the enhancement of thermoelectric power factor. We find that the power factor can be enhanced to 28.46 {\mu}W/mK2 when the CNT is doped with 0.5 {\mu}g/ml of 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) before co-embedding silica microparticles within the carbon nanotube-based composite. We also fabricated and demonstrated flexible wearable thermoelectric devices made of the developed composites that exhibits a power output of 0.025 {\mu}W/cm2 at a temperature differential of only 4 K.

physics.app-ph↗

arXiv2022

Mid-circuit correction of correlated phase errors using an array of spectator qubits

Scaling up invariably error-prone quantum processors is a formidable challenge. While quantum error correction ultimately promises fault-tolerant operation, the required qubit overhead and error thresholds are daunting, and many codes break down under correlated noise. Recent proposals have suggested a complementary approach based on co-located, auxiliary 'spectator' qubits. These act as in-situ probes of noise, and enable real-time, coherent corrections of the resulting errors on the data qubits. Here, we use an array of cesium spectator qubits to correct correlated phase errors on an array of rubidium data qubits. Crucially, by combining in-sequence readouts, data processing, and feed-forward operations, these correlated errors are suppressed within the execution of the quantum circuit. The protocol is broadly applicable to quantum information platforms, and our approach establishes key tools for scaling neutral-atom quantum processors: mid-circuit readout of atom arrays, real-time processing and feed-forward, and coherent mid-circuit reloading of atomic qubits.

quant-ph↗

arXiv2017

Symmetries of a reduced fluid-gyrokinetic system

Symmetries of a fluid-gyrokinetic model are investigated using Lie group techniques. Specifically the nonlinear system constructed by Zocco and Schekochihin (Zocco & Schekochihin 2011), which combines nonlinear fluid equations with a drift-kinetic description of parallel electron dynamics, is studied. Significantly, this model is fully gyrokinetic, allowing for arbitrary k_perp rho_i , where k_perp is the perpendicular wave vector of the fluctuations and rho_i the ion gyroradius. The model includes integral operators corresponding to gyroaveraging as well as the moment equations relating fluid variables to the kinetic distribution function. A large variety of exact symmetries is uncovered, some of which have unexpected form. Using these results, new nonlinear solutions are constructed, including a helical generalization of the Chapman-Kendall solution for a collapsing current sheet.

physics.plasm-ph↗

arXiv2002

Inelastic impact of a sphere on a massive plane: nonmonotonic velocity-dependence of the restitution coefficient

We have studied the coefficient of restitution, $η$, in normal collisions of a non-rotating sphere on a massive plate for a range of material parameters, impact velocity and sphere size. The measured coefficient of restitution does not monotonically vary with velocity. This effect is due to dynamics that occur during the finite duration of impact: the contact time varies as a function of velocity is comparable to the time-scales of the vibrational modes of the plate. The measured effect is robust and is expected to be ubiquitous in fluidized granular media. We also find that $η$ is a decreasing function of particle size, a dependence that is not captured by existing models of impact.

cond-mat.soft↗