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Cold-Atom Rydberg Array with Spatiotemporal Multiplexing for High-Sensitivity Wireless Communications

Jian Xiao, Tierui Gong, Chau Yuen

arXiv:2610.07642v1cs.ITmath.IT

TL;DR

Turning CoRA quantum electrometers into wireless receivers is challenging because destructive readout creates macroscopic dead time and atomic counts are nonlinear binomial observations. The paper proposes subarray scheduling and burst-wise binomial inference, and reports gap-free in-burst sampling, lower BER, and an atom-number sensitivity–sustainability tradeoff.

  • Problem

    CoRA-based wireless reception must contend with destructive readout dead time and nonlinear binomial counts rather than conventional additive-Gaussian samples.

    Source: §VI · p. 12

  • Method

    The paper schedules preloaded atom subarrays across symbol intervals and uses a joint binomial particle smoother for burst-wise state and data inference.

    Source: §VI · p. 12

  • Results

    Numerical results show gap-free in-burst sampling and superior BER over considered baselines, while weak-signal SNR scales as Km and sustainable packet repetition frequency as Km^-1 in the QPN- and atom-flux-limited regime.

    Source: §VI · p. 12

  • Takeaways & Limitations

    Within the QPN- and atom-flux-limited regime, increasing active atom number improves weak-signal SNR but reduces sustainable packet repetition frequency.

    Source: §VI · p. 12

    STM provides gap-free interrogation within an admitted burst, while indefinitely sustainable operation remains constrained by atomic recovery and replenishment rates.

    Source: 3) Recovery Latency and Atom-Flux… · p. 5

Abstract

from arXiv · show

An effective Cold-Atom Rydberg Array (CoRA) architecture is investigated, which addresses the fundamental thermal noise limit in classical electromagnetics and intrinsic Doppler broadening as well as photon shot noise in conventional hot-vapor cell-based atomic receivers. However, translating the CoRA-based quantum electrometers into practical wireless communication receivers is bottlenecked by both the macroscopic readout dead-times and nonlinear binomial population counts rather than the additive-Gaussian baseband samples in conventional receivers. To address these critical challenges and facilitate the practicality of the CoRA, in this paper, a subarray scheduling-based spatiotemporal multiplexing (STM) framework is first proposed for gap-free symbol interrogation within an admitted packet. Additionally, a signal detection scheme based on a joint binomial particle smoother (JBPS) is proposed for burst-wise state and data inference. Furthermore, the weak-signal quantum-projection-noise (QPN) limit and the state-averaged finite-alphabet rate are derived for CoRA-assisted wireless communications. Numerical results demonstrate that: 1) The proposed STM-based CoRA scheme resolves the macroscopic temporal bottleneck for continuous signal sampling; 2) The proposed JBPS approach effectively mitigates the nonlinear noise amplification to achieve a lower bit error rate; and 3) Performance analysis reveals a fundamental sensitivity-sustainability tradeoff that increasing the number of atoms effectively suppresses the QPN, but simultaneously reduces the sustainable packet repetition rate.

I. INTRODUCTION

CoRA offers individually read, laser-cooled atoms, but applying it to wireless communication requires addressing destructive readout, nonlinear binomial observations, and atom-replenishment constraints. The paper combines subarray scheduling, burst-wise inference, and performance analysis to study these challenges.

I. INTRODUCTION

  • Existing CoRA studies largely estimate controlled quasi-stationary fields, leaving continuous recovery of modulated communication waveforms under finite-atom and replenishment constraints as an open question.Conventional vapor-cell receivers also face Doppler broadening, collisional decoherence, and spatially nonuniform coupling.Source: §I · p. 1

A. Prior Works

  • Vapor-cell receivers use ensemble optical readout, whereas CoRA isolates laser-cooled atoms for single-atom state-selective fluorescence readout.The paper contrasts the hot-vapor and CoRA architectures; CoRA's single-atom readout yields binomial projection statistics and avoids collision-induced decoherence.Source: A. Prior Works · pp. 1–2, Figure 1 · p. 2

B. Motivations and Contributions

  • STM uses a steady-state dual-lattice atom supply and optical steering to multiplex stationary subarrays into a continuous-time burst-packet receiver.The framework is designed to overcome the temporal-resolution constraints of discrete-time quantum sensing.Source: B. Motivations and Contributions · p. 2
  • JBPS uses an exact I/Q binomial observation model and a three-dimensional latent state to infer burst-wise state and data from the full finite burst.It forms bitwise posterior decisions after using all burst observations.Source: B. Motivations and Contributions · p. 2
  • The performance framework relates active atom number to receiver sensitivity, finite-alphabet rate, and long-term packet sustainability, including crossover conditions against specified benchmarks.It also derives the minimum active atoms per subarray required to outperform the specified classical-antenna and hot-vapor-cell benchmarks.Source: B. Motivations and Contributions · p. 3
  • The proposed STM enables gap-free in-burst sampling, JBPS achieves lower BER than considered baselines, and weak-signal SNR and sustainable packet repetition frequency scale oppositely with atom number.In the QPN- and atom-flux-limited regime, weak-signal SNR scales linearly with Km while packet repetition frequency scales as Km^-1.Source: B. Motivations and Contributions · p. 3

A. Pulsed CoRA for Microwave Electrometry

  • In the pulsed CoRA platform, a movable tweezer transports selected atoms from a reservoir to a target zone for preparation, microwave interrogation, and readout.Single-atom isolation suppresses collision-induced decoherence, while atomic motion, laser noise, trap inhomogeneity, spontaneous decay, and blackbody-radiation coupling remain relevant.Source: • Reservoir zone · p. 3, A. Pulsed CoRA for Microwave… · p. 3, Figure 2 · p. 3

2) Single-Atom Homodyne Measurement:

The single-atom homodyne model converts a calibrated weak microwave field into a binary state outcome, with grouped atoms yielding binomial counts. The destructive measurement cycle is much slower than coherent interaction, limiting direct use for real-time wireless communication.

2) Single-Atom Homodyne Measurement:

  • A calibrated phase reference and final π/2 analysis rotation yield an ideal single-shot state-projection probability, with readout errors and visibility loss incorporated into the observed probability.For conditionally independent atoms at the same calibrated point, the upper-state count is binomial; the weak-field Rabi-frequency uncertainty is QPN-limited at maximum slope.Source: 2) Single-Atom Homodyne Measurement · pp. 3–4

3) Dead Time of Pulsed Measurement Cycle:

  • A 53-Hz destructive cycle with 20 µs interrogation has duty factor about 1.06×10^-3, so fast coherent interaction does not provide real-time wireless sampling.The cycle includes macroscopic dead time for loading, transport, state preparation, and readout.Source: 3) Dead Time of Pulsed Measurement Cycle · p. 4

B. Continuous-Operation CoRA Architecture

The continuous-operation CoRA separates atom supply from coherence-sensitive sensing, while STM schedules fresh I/Q subarrays to provide gap-free interrogation during an admitted burst. The architecture combines spatially interleaved atom groups with a temporal schedule that trades per-pair reuse time for aggregate symbol-rate sampling.

B. Continuous-Operation CoRA Architecture

2) Preparation Zone:

  • The binomial model assumes independent sites with a shared calibrated success probability; unequal probabilities yield Poisson–binomial counts without changing STM scheduling.Source: 2) Preparation Zone · p. 4

4) Continuous Spectral Shielding Mechanism:

  • A 1529-nm shielding beam applies selective AC Stark shifts to suppress scattering during simultaneous cooling and imaging.The pulsed cycle is limited by interrogation plus reset time, while foreground interrogation is bounded by interrogation plus optical switching time.Source: 4) Continuous Spectral Shielding… · p. 4

A. Proposed Spatiotemporal Multiplexing Framework

1) Interleaved Spatial Partition:

  • The lattice sites are partitioned into M scheduled I/Q pairs, with balanced branches using 2Km atoms per snapshot.The interleaved partition distributes each group over the lattice footprint.Source: 1) Interleaved Spatial Partition · p. 4

2) Temporal Scheduling and Foreground Duty Factor:

3) Recovery Latency and Atom-Flux Constraint:

STM rotates fresh subarrays across symbols, but reuse and indefinite operation remain bounded by atomic recovery and replenishment. The section also specifies spatial separation, site-count observations, and the burst protocol’s atom-budget constraints.

3) Recovery Latency and Atom-Flux Constraint:

4) Atomic Spacing Constraint:

  • Atoms excited simultaneously in an I/Q pair should be separated by at least the blockade radius, typically about 5–10 µm for principal quantum numbers 50–70.Source: 4) Atomic Spacing Constraint · p. 5

5) Observation Mapping:

  • The observation mapping selects each branch’s sites from the binary lattice outcomes and sums them into symbol-rate I/Q counts.Source: 5) Observation Mapping · p. 6

B. Communication Protocol and Atomic Observation

C. Atom State Tracking and Binomial Likelihood

The receiver tracks phase, frequency offset, and effective Rabi gain as a latent state because coherent recovery depends on these unknown, time-varying quantities. The state predicts nonlinear binomial I/Q counts, making point-estimate detection vulnerable to residual state uncertainty and multimodality.

1) Dynamic Phase and Rabi-Gain State:

  • Unknown carrier-reference phase, residual frequency offset, and oscillator phase noise require joint inference of relative phase and effective field-to-Rabi gain.Source: 1) Dynamic Phase and Rabi-Gain State · p. 6
  • The latent state tracks relative phase, phase increment, and logarithmic Rabi gain, with process noise representing their symbol-to-symbol variation.The gain is modeled as approximately constant within a short burst, while allowing small residual amplitude and calibration variations.Source: 1) Dynamic Phase and Rabi-Gain State · p. 7
  • The Rabi-angle response is periodic, so local inversion can amplify noise and become ambiguous near or beyond a Rabi fold.With Km atoms per branch, the I and Q counts follow binomial observation models.Source: 1) Dynamic Phase and Rabi-Gain State · p. 7
  • A plug-in detector treats one predicted state as true, neglecting residual state uncertainty and possible multimodality.Source: 1) Dynamic Phase and Rabi-Gain State · p. 7

D. Proposed Joint Binomial Particle Smoother-Based Signal Detection Scheme for CoRA Systems

JBPS combines particle filtering with backward-simulation smoothing to infer burst state and data under nonlinear, non-Gaussian binomial observations. It retains the exact likelihood and accounts for uncertain payload symbols during state tracking.

D. Proposed Joint Binomial Particle Smoother-Based Signal Detection Scheme for CoRA Systems

IV. PERFORMANCE ANALYSIS FOR CORA SYSTEMS

The section establishes a common input-field and noise-bandwidth basis for comparing receiver sensitivity, then develops the antenna and vapor-cell receiver models.

1) Common Reference Plane and Noise Convention:

  • The comparison uses a shared incident field and one-sided noise bandwidth, with weak-signal SNR defined from the input-referred noise-equivalent field.The weak-signal expression assumes approximately white noise over the equivalent noise bandwidth.Source: 1) Common Reference Plane and Noise… · p. 8

2) Classical Antenna-Based Receiver:

  • The classical antenna model derives available signal and thermal-noise powers from effective aperture and system temperature, then obtains SNR and input-referred NEF.The antenna is characterized by realized gain and wavelength; system temperature combines antenna temperature and receiver noise figure.Source: 2) Classical Antenna-Based Receiver · p. 8

3) Vapor Cell-Based Atomic Receiver:

  • The vapor-cell analysis maps the atomic response through optical conversion and balanced detection to output gain, weak-signal SNR, and input-referred NEF.The optical homodyne phase is locked to the maximum-slope quadrature.Source: 3) Vapor Cell-Based Atomic Receiver · p. 8
  • The vapor-cell model uses RF-LO-biased coherent detection and includes electronic thermal, photon-shot, and atomic quantum-projection noise.Its weak-signal equations apply only in the locally linear RF-LO-biased regime; strong-field results use the full nonlinear susceptibility.Source: 3) Vapor Cell-Based Atomic Receiver · pp. 8–9

4) CoRA-Based Atomic Receiver:

The CoRA analysis relates exact binomial observations to weak-field sensitivity and shows how paired I/Q branches remove phase-dependent sensitivity nulls.

4) CoRA-Based Atomic Receiver:

  • At the common incident-field plane, the effective field-to-Rabi coefficient is defined, and the exact-binomial observation yields conditional field-amplitude Fisher information.The Fisher information is conditioned on tracked phase.Source: 4) CoRA-Based Atomic Receiver · p. 9
  • For q = κaEτint ≪ 1 and conditioned on ψ, the weak-field lemma gives the array Fisher information.Source: 4) CoRA-Based Atomic Receiver · p. 9
  • Complementary cos^2 ψ and sin^2 ψ contributions make local amplitude sensitivity phase-invariant, but phase tracking remains necessary for I/Q symbol mapping.Source: 4) CoRA-Based Atomic Receiver · p. 9

5) Conditional Cross-Receiver Sensitivity Comparison:

The section gives a conditional criterion for CoRA sensitivity to exceed another receiver and defines an achievable rate suited to finite-alphabet binomial counts.

5) Conditional Cross-Receiver Sensitivity Comparison:

  • At the same input-field reference plane and noise bandwidth, the array has higher local weak-signal SNR than receiver r if and only if its NEF is lower.Source: 5) Conditional Cross-Receiver… · p. 9
  • Under the QPN-only array model, crossover atom numbers for antenna and vapor-cell receivers follow from the sensitivity condition and their corresponding NEFs.A finite crossover requires the stated field-floor condition; no numerical threshold is given in these passages.Source: 5) Conditional Cross-Receiver… · p. 9

B. State-Averaged Finite-Alphabet Rate

  • Because finite-count binomial observations are not characterized by Gaussian-input Shannon capacity, the section defines a state-conditioned finite-alphabet rate and then averages over the state process.The state-averaged rate is specified for a given input distribution and state process.Source: B. State-Averaged Finite-Alphabet Rate · p. 9

C. Hardware-Constrained Information-PRF Tradeoff

The analysis links active atom number to weak-field sensitivity and sustainable packet rate, while the numerical-results section describes the receiver and burst-detection evaluations.

C. Hardware-Constrained Information-PRF Tradeoff

  • In the weak-field QPN-limited and atom-flux-limited regime, increasing Km raises weak-signal SNR while reducing sustainable packet repetition frequency as Km^-1.The corresponding QPN-limited NEF decreases as Km^-1/2, and the SNR–PRF product is independent of Km under the stated assumptions.Source: C. Hardware-Constrained… · p. 9
  • With a fixed atom supply, increasing atom number reallocates resources between instantaneous sensitivity and long-term packet sustainability rather than providing an unconstrained gain.Source: C. Hardware-Constrained… · pp. 9–10

V. NUMERICAL RESULTS

  • The numerical-results section evaluates STM and JBPS for CoRA communications and compares communication metrics across classical-antenna, vapor-cell, and CoRA receivers.Source: §V · p. 10

A. Simulation Setups

  • The receiver comparison uses a common incident peak field and 1 MHz noise bandwidth; burst-detection baselines share transmitted bursts, dynamic states, and binomial observations.The setup includes pilot-based BMAP, EKF-BMAP, decision-directed EKF, and a nonimplementable oracle reference.Source: A. Simulation Setups · p. 10

B. Performance Evaluation for Burst Communications

The evaluation finds a sensitivity–sustainability tradeoff as atom number increases, while STM supports gap-free interrogation within admitted bursts and JBPS improves burst detection. Receiver comparisons also show finite-alphabet rate gains in the considered weak-field region and interaction-time tradeoffs.

B. Performance Evaluation for Burst Communications

  • JBPS approaches the Oracle and provides substantially lower BER than frozen-state and plug-in baselines by smoothing multiple latent-state hypotheses over burst observations.At high transmit power, BER turns upward because the atomic response is periodic in the Rabi angle.Source: B. Performance Evaluation for Burst… · p. 11, Figure 7 · p. 11
  • Beyond the first Rabi fold at q_n = π/2, distinct Rabi angles can produce the same atomic response, creating a dynamic-range constraint.The marked guide indicates that 5% of channel realizations drive the maximum-radius symbol beyond the first fold.Source: B. Performance Evaluation for Burst… · p. 11
  • As K_m increases, Oracle and JBPS BER continue to improve, while BMAP retains a higher error floor from frozen-state mismatch and EKF receivers are increasingly limited by state-estimation error.JBPS remains closest to Oracle by marginalizing payload uncertainty and smoothing state over the burst.Source: B. Performance Evaluation for Burst… · p. 11, Figure 8 · p. 11
  • At K_m = 343 with N_b = 16, the single-use buffer boundary is K_0 = 10,976 initialized atoms; larger arrays require a larger buffer or atom reinitialization or reuse.Values beyond this boundary are not claimed feasible as single-use bursts under the same buffer.Source: B. Performance Evaluation for Burst… · p. 11

C. Performance Comparison for Different Receivers

  • The K_m = 5500 CoRA array has the highest SNR, but a single-use K_m = 343 array does not universally outperform the classical and vapor references.At stronger fields, CoRA SNR exhibits repeated peaks and nulls from periodic Rabi response, unlike the displayed linear classical benchmark.Source: C. Performance Comparison for… · pp. 11–12, Figure 9 · p. 12
  • Within the considered weak-field region, CoRA reaches a given finite-alphabet rate at lower transmit power, and all three receivers approach the 2 Mbit/s QPSK ceiling.The common ceiling follows from the finite QPSK alphabet for T_sym = 1 µs.Source: C. Performance Comparison for… · p. 12, Figure 10 · p. 12
  • At τ_int = 0.9 µs, the annotated crossings occur at approximately K_m = 964 for the classical reference and K_m = 1977 for the optimized vapor reference.Longer interaction reduces the atoms needed to cross a prescribed SNR, but lowers the first-fold field and constrains foreground-control time and symbol period.Source: C. Performance Comparison for… · p. 12, Figure 11 · p. 12

VI. CONCLUSION

  • In the QPN-limited and atom-flux-limited regime, increasing K_m linearly improves weak-signal SNR but reduces sustainable packet repetition frequency as K_m^-1.The conclusion identifies this as a sensitivity–sustainability scaling law.Source: §VI · p. 12

APPENDIX A PROOF OF LEMMA 1

The appendix derives the field-amplitude Fisher information for matched I/Q branches at the zero-field operating point. Substitution establishes Eq. (57) and the subsequent expressions in Eqs. (58) and (59).

APPENDIX A PROOF OF LEMMA 1

  • The matched I/Q branches have excitation probabilities, and their conditionally independent binomial counts contribute additively to Fisher information.The appendix uses this sum to form the field-amplitude Fisher information.Source: Appendix A · p. 12
  • Using sin q = q + O(q^3), the proof evaluates the required quantities at the zero-field operating point and substitutes them into Eq. (73).Source: Appendix A · p. 12
  • The substitution proves Eq. (57), whose leading-order expression is independent of the tracked phase, and yields Eqs. (58) and (59).Source: Appendix A · p. 13
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