Stable, bidirectional electro-optic transduction in thin film lithium tantalate
Pith reviewed 2026-06-27 09:11 UTC · model grok-4.3
The pith
Thin-film lithium tantalate enables the first stable bidirectional microwave-optical transducers with multi-day operation on a static bias.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We demonstrate the first integrated electro-optic microwave-optical transducers realized in thin-film lithium tantalate, observing coherent bidirectional conversion between C-band optical photons and 4.9-5.5 GHz microwave photons with measured on-chip efficiencies and inferred single-photon coupling rates g0/2π ~ 1 kHz consistent with theory, and continuous operation over multiple days using a static bias field with minimal feedback.
What carries the argument
Superconducting microwave resonators coupled to tunable photonic-molecule optical resonators fabricated in thin-film lithium tantalate, using its Pockels nonlinearity to mediate the microwave-to-optical interaction.
If this is right
- Bidirectional conversion supports quantum state transfer in both directions for modular quantum processors.
- Static bias operation reduces the need for continuous active stabilization in deployed quantum networks.
- Wafer-scale deep ultraviolet lithography enables high-volume production of transducers for large-scale interconnects.
- Low added noise under pulsed pumping allows compatibility with superconducting qubit readout and control cycles.
- Improved high-power handling and stability position the platform for higher-efficiency operation in future devices.
Where Pith is reading between the lines
- The reported optical loss statistics could be used to predict device yield improvements through process optimization.
- If the coupling rates scale with device geometry as expected, smaller mode volumes might increase g0 without changing the material.
- The combination of stability and bidirectional operation could simplify calibration procedures in heterogeneous quantum systems.
- Pulsed operation data suggests the platform might tolerate higher average powers in continuous-wave regimes than lithium niobate equivalents.
Load-bearing premise
The material properties of thin-film lithium tantalate, including its Pockels nonlinearity and bias stability, produce working devices with the reported efficiencies and long-term stability without major unaccounted losses or fabrication variations.
What would settle it
A direct measurement on multiple devices showing on-chip conversion efficiency far below the value predicted from the observed coupling rate g0, or bias voltage drift requiring adjustments within hours rather than days of continuous operation.
Figures
read the original abstract
Efficient and stable microwave-optical transduction is a key enabling technology for distributed superconducting quantum computing and heterogeneous quantum networks. Electro-optic transducers based on thin-film lithium niobate (TFLN) have shown strong promise, but demonstrations to date have been limited by various factors such as low frequency bias drift, low efficiency, fabrication complexity, and scalability. Here we demonstrate the first integrated electro-optic microwave-optical transducers realized in thin-film lithium tantalate (TFLT), a material platform offering Pockels nonlinearity comparable to TFLN together with improved bias stability and high-power handling. We fabricate superconducting microwave resonators coupled to tunable photonic-molecule optical resonators using wafer-scale deep ultraviolet lithography, offering high-throughput production of hundreds of devices per wafer. Across six devices we observe coherent bidirectional conversion between C-band optical photons and 4.9-5.5 GHz microwave photons, with measured on-chip efficiencies and inferred single-photon coupling rates g_0/2{\pi} ~ 1 kHz consistent with theory. Continuous operation over multiple days is achieved using a static bias field with minimal feedback, demonstrating a major operational advantage. We further characterize optical loss statistics, microwave resonator performance, and optically induced added noise under pulsed pumping, finding less than one added photon for 100 microsecond pulses at the highest measured efficiencies. These results establish TFLT as a scalable and robust electro-optic platform for future quantum interconnects and modular quantum processors.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript reports the first demonstration of integrated electro-optic microwave-to-optical transducers fabricated in thin-film lithium tantalate (TFLT). Using wafer-scale DUV lithography, the authors realize superconducting microwave resonators coupled to tunable photonic-molecule optical resonators. Across six devices, they observe coherent bidirectional conversion between C-band optical photons and 4.9-5.5 GHz microwaves, with measured on-chip efficiencies and inferred single-photon coupling rates g_0/2π ≈ 1 kHz stated to be consistent with theory. Continuous multi-day operation is achieved with a static bias field and minimal feedback. Additional characterization covers optical loss statistics, microwave resonator performance, and optically induced added noise under pulsed pumping, reporting less than one added photon for 100 μs pulses at peak efficiencies. The work positions TFLT as offering Pockels nonlinearity comparable to TFLN with improved bias stability and power handling.
Significance. If the reported efficiencies, coupling rates, bidirectional coherence, and multi-day stability hold under full scrutiny, the result is significant as the first experimental validation of TFLT for integrated electro-optic transduction. It directly addresses documented limitations of TFLN devices (bias drift, power handling) while retaining comparable nonlinearity. The wafer-scale fabrication of hundreds of devices per wafer and the explicit multi-device statistics provide evidence of scalability. The static-bias stability demonstration and pulsed-noise characterization are concrete operational advantages for quantum-network applications. These strengths are grounded in the experimental platform choice and the breadth of reported metrics rather than in any parameter-free derivation.
major comments (3)
- [Abstract] Abstract and Results: The central claims of 'measured on-chip efficiencies' and 'inferred single-photon coupling rates g_0/2π ~ 1 kHz consistent with theory' across six devices are presented without reported uncertainties, error bars, or the number of independent measurements per device. This omission directly affects assessment of whether unaccounted optical or microwave loss channels alter the extracted values, which is load-bearing for the performance comparison to TFLN and the claim of theory consistency.
- [Results] Results (multi-day operation paragraph): The claim of 'continuous operation over multiple days ... with minimal feedback' is central to the operational-advantage argument, yet no drift plots, bias-voltage time series, or quantitative stability metrics (e.g., frequency shift per hour) are referenced. Without these data, it is impossible to verify that fabrication variations or hidden loss mechanisms do not compromise the reported stability.
- [Methods] Methods or supplementary information: The procedure for extracting on-chip efficiencies (including calibration of all loss channels and any assumptions about coupling or propagation losses) is not described at a level that allows independent verification that the reported numbers are free of unaccounted mechanisms. This extraction step is load-bearing for the efficiency and g_0 claims.
minor comments (2)
- [Abstract] Abstract: The notation 'g_0/2{π}' contains a LaTeX formatting artifact that should be rendered as g_0/2π.
- The manuscript would benefit from a table summarizing the six devices (efficiencies, g_0 values, resonance frequencies, and stability durations) to make the multi-device statistics immediately accessible.
Simulated Author's Rebuttal
We thank the referee for their detailed and constructive review. The comments highlight important points regarding data presentation and methodological transparency that we will address in the revision. Below we respond point-by-point to the major comments.
read point-by-point responses
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Referee: [Abstract] Abstract and Results: The central claims of 'measured on-chip efficiencies' and 'inferred single-photon coupling rates g_0/2π ~ 1 kHz consistent with theory' across six devices are presented without reported uncertainties, error bars, or the number of independent measurements per device. This omission directly affects assessment of whether unaccounted optical or microwave loss channels alter the extracted values, which is load-bearing for the performance comparison to TFLN and the claim of theory consistency.
Authors: We agree that explicit uncertainties and measurement statistics are necessary for rigorous evaluation. In the revised manuscript we will add error bars to the reported efficiencies and g_0 values (derived from the standard deviation across repeated measurements on each device), state the number of independent measurements per device (typically 3–5 per device across the six devices), and briefly describe how optical and microwave loss channels were calibrated and subtracted in the extraction procedure. These additions will be placed in both the abstract/results and the methods/supplementary sections to support the consistency claim with theory. revision: yes
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Referee: [Results] Results (multi-day operation paragraph): The claim of 'continuous operation over multiple days ... with minimal feedback' is central to the operational-advantage argument, yet no drift plots, bias-voltage time series, or quantitative stability metrics (e.g., frequency shift per hour) are referenced. Without these data, it is impossible to verify that fabrication variations or hidden loss mechanisms do not compromise the reported stability.
Authors: We acknowledge that quantitative stability data would strengthen the multi-day operation claim. In the revision we will add a supplementary figure (or extended data panel) showing representative bias-voltage time series and optical resonance frequency drift over >48 hours under static bias, together with extracted metrics such as average frequency shift per hour. These data were collected during the experiments but were not included in the original submission; their addition will directly address the concern about hidden drift or fabrication variations. revision: yes
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Referee: [Methods] Methods or supplementary information: The procedure for extracting on-chip efficiencies (including calibration of all loss channels and any assumptions about coupling or propagation losses) is not described at a level that allows independent verification that the reported numbers are free of unaccounted mechanisms. This extraction step is load-bearing for the efficiency and g_0 claims.
Authors: We agree that a fully documented extraction procedure is required for independent verification. In the revised supplementary information we will provide a step-by-step description of the on-chip efficiency calibration, including (i) how optical coupling and propagation losses were measured and subtracted using reference devices, (ii) the microwave resonator internal and external loss rates extracted from circle fits, and (iii) the assumptions made regarding frequency-dependent losses. This expanded methods section will allow readers to reproduce the reported efficiencies and g_0 values from the raw data. revision: yes
Circularity Check
No circularity: experimental device report with direct measurements
full rationale
This is a purely experimental paper reporting fabrication of TFLT transducers via wafer-scale lithography, bidirectional conversion measurements across six devices, on-chip efficiencies, g0/2π ~1 kHz values, and multi-day static-bias stability. No derivations, fitted-parameter predictions, self-citation load-bearing steps, or ansatzes appear in the abstract or described results. All claims rest on observed data and consistency with external theory, with no reduction of outputs to inputs by the paper's own equations. The reader's assessment of score 0.0 is confirmed.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Thin-film lithium tantalate exhibits Pockels nonlinearity comparable to thin-film lithium niobate while providing improved bias stability and high-power handling.
Reference graph
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