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Quantum Sensors for Chemistry and Materials Science
Authors:
Piotr Put,
Arjun Pillai,
Xuan Hoang Le,
Mikhail D. Lukin,
Hongkun Park
Abstract:
The advancement of chemistry and materials science relies on transformative analytical tools which can overcome the sensitivity, spatial resolution, and throughput limitations of conventional techniques. This review explores the application of quantum sensors - specifically optically pumped magnetometers (OPMs) and nitrogen-vacancy (NV) centers in diamond - as robust platforms for molecular and ma…
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The advancement of chemistry and materials science relies on transformative analytical tools which can overcome the sensitivity, spatial resolution, and throughput limitations of conventional techniques. This review explores the application of quantum sensors - specifically optically pumped magnetometers (OPMs) and nitrogen-vacancy (NV) centers in diamond - as robust platforms for molecular and materials analysis. We contrast the extreme magnetic sensitivity of macroscopic OPM ensembles with the atomic-scale resolution and multimodal capabilities of solid-state NV centers. We highlight their deployment in zero- to ultralow-field and nanoscale NMR spectroscopy, real-time reaction monitoring, and transient radical and pH detection. Furthermore, we discuss their integration into high-throughput chemical assays and non-destructive materials diagnostics, such as operando battery monitoring. With the ongoing commercialization of these technologies and advances in quantum-enhanced sensitivities, quantum sensors are poised to routinely address complex real-world analytical challenges.
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Submitted 8 July, 2026;
originally announced July 2026.
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Wideband covariance magnetometry below the diffraction limit
Authors:
Xuan Hoang Le,
Pavel E. Dolgirev,
Piotr Put,
Eric L. Peterson,
Arjun Pillai,
Alexander A. Zibrov,
Eugene Demler,
Hongkun Park,
Mikhail D. Lukin
Abstract:
We experimentally demonstrate a method for measuring correlations of wideband magnetic signals with spatial resolution below the optical diffraction limit. Our technique employs two nitrogen-vacancy (NV) centers in diamond as nanoscale magnetometers, spectrally resolved by inhomogeneous optical transitions. Using high-fidelity optical readout and long spin coherence time, we probe correlated MHz-r…
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We experimentally demonstrate a method for measuring correlations of wideband magnetic signals with spatial resolution below the optical diffraction limit. Our technique employs two nitrogen-vacancy (NV) centers in diamond as nanoscale magnetometers, spectrally resolved by inhomogeneous optical transitions. Using high-fidelity optical readout and long spin coherence time, we probe correlated MHz-range noise with sensitivity of 15 nT Hz$^{-1/4}$. In addition, we use this system for correlated $T_1$ relaxometry, enabling correlation measurements of GHz-range noise. Under such externally applied noise, while individual NV centers exhibit featureless relaxation, their correlation displays rich coherent and incoherent dynamics reminiscent of superradiance physics. This capability to probe high-frequency correlations provides a powerful tool for investigating a variety of condensed-matter phenomena characterized by nonlocal correlations.
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Submitted 30 April, 2025;
originally announced May 2025.
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Disentangling Losses in Tantalum Superconducting Circuits
Authors:
Kevin D. Crowley,
Russell A. McLellan,
Aveek Dutta,
Nana Shumiya,
Alexander P. M. Place,
Xuan Hoang Le,
Youqi Gang,
Trisha Madhavan,
Nishaad Khedkar,
Yiming Cady Feng,
Esha A. Umbarkar,
Xin Gui,
Lila V. H. Rodgers,
Yichen Jia,
Mayer M. Feldman,
Stephen A. Lyon,
Mingzhao Liu,
Robert J. Cava,
Andrew A. Houck,
Nathalie P. de Leon
Abstract:
Superconducting qubits are a leading system for realizing large scale quantum processors, but overall gate fidelities suffer from coherence times limited by microwave dielectric loss. Recently discovered tantalum-based qubits exhibit record lifetimes exceeding 0.3 ms. Here we perform systematic, detailed measurements of superconducting tantalum resonators in order to disentangle sources of loss th…
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Superconducting qubits are a leading system for realizing large scale quantum processors, but overall gate fidelities suffer from coherence times limited by microwave dielectric loss. Recently discovered tantalum-based qubits exhibit record lifetimes exceeding 0.3 ms. Here we perform systematic, detailed measurements of superconducting tantalum resonators in order to disentangle sources of loss that limit state-of-the-art tantalum devices. By studying the dependence of loss on temperature, microwave photon number, and device geometry, we quantify materials-related losses and observe that the losses are dominated by several types of saturable two level systems (TLSs), with evidence that both surface and bulk related TLSs contribute to loss. Moreover, we show that surface TLSs can be altered with chemical processing. With four different surface conditions, we quantitatively extract the linear absorption associated with different surface TLS sources. Finally, we quantify the impact of the chemical processing at single photon powers, the relevant conditions for qubit device performance. In this regime we measure resonators with internal quality factors ranging from 5 to 15 x 10^6, comparable to the best qubits reported. In these devices the surface and bulk TLS contributions to loss are comparable, showing that systematic improvements in materials on both fronts will be necessary to improve qubit coherence further.
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Submitted 18 January, 2023;
originally announced January 2023.
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Chemical profiles of the oxides on tantalum in state of the art superconducting circuits
Authors:
Russell A. McLellan,
Aveek Dutta,
Chenyu Zhou,
Yichen Jia,
Conan Weiland,
Xin Gui,
Alexander P. M. Place,
Kevin D. Crowley,
Xuan Hoang Le,
Trisha Madhavan,
Youqi Gang,
Lukas Baker,
Ashley R. Head,
Iradwikanari Waluyo,
Ruoshui Li,
Kim Kisslinger,
Adrian Hunt,
Ignace Jarrige,
Stephen A. Lyon,
Andi M. Barbour,
Robert J. Cava,
Andrew A. Houck,
Steven L. Hulbert,
Mingzhao Liu,
Andrew L. Walter
, et al. (1 additional authors not shown)
Abstract:
Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces. We recently…
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Over the past decades, superconducting qubits have emerged as one of the leading hardware platforms for realizing a quantum processor. Consequently, researchers have made significant effort to understand the loss channels that limit the coherence times of superconducting qubits. A major source of loss has been attributed to two level systems that are present at the material interfaces. We recently showed that replacing the metal in the capacitor of a transmon with tantalum yields record relaxation and coherence times for superconducting qubits, motivating a detailed study of the tantalum surface. In this work, we study the chemical profile of the surface of tantalum films grown on c-plane sapphire using variable energy X-ray photoelectron spectroscopy (VEXPS). We identify the different oxidation states of tantalum that are present in the native oxide resulting from exposure to air, and we measure their distribution through the depth of the film. Furthermore, we show how the volume and depth distribution of these tantalum oxidation states can be altered by various chemical treatments. By correlating these measurements with detailed measurements of quantum devices, we can improve our understanding of the microscopic device losses.
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Submitted 20 January, 2023; v1 submitted 11 January, 2023;
originally announced January 2023.