Morgan W. Mitchell
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View article: Using Air Quality Alerts to Estimate Population-Based Wildfire Smoke Exposure from the 2023 Canadian Wildfire Season
Using Air Quality Alerts to Estimate Population-Based Wildfire Smoke Exposure from the 2023 Canadian Wildfire Season Open
Wildfires are a source of air pollution, which impacts air quality in proximity to and at great distances from fires. Wildfire smoke exposure is seasonal and episodic, with exposure levels and durations that can vary considerably. Exposure…
View article: Optimal and efficient inference tools for field tracking with precessing spins
Optimal and efficient inference tools for field tracking with precessing spins Open
Precise, real-time monitoring of magnetic field evolution is important in applications including magnetic navigation and searches for physics beyond the standard model. One main field-monitoring technique, the spin-precession magnetometer …
View article: Sequential analysis in a continuous spin-noise quantum sensor
Sequential analysis in a continuous spin-noise quantum sensor Open
Many control and detection applications require real-time analysis of signals from sensors, in order to quickly and accurately act upon events revealed by the sensors. Such signal analysis benefits from statistical models of signal and sen…
View article: Quantum noise in a squeezed-light-enhanced multiparameter quantum sensor
Quantum noise in a squeezed-light-enhanced multiparameter quantum sensor Open
We study quantum enhancement of sensitivity using squeezed light in a multi-parameter quantum sensor, the hybrid rf-dc optically pumped magnetometer (hOPM) [Phys. Rev. Applied 21, 034054, (2024)]. Using a single spin ensemble, the hOPM acq…
View article: Tracking time-varying signals with quantum-enhanced atomic magnetometers
Tracking time-varying signals with quantum-enhanced atomic magnetometers Open
Quantum entanglement, in the form of spin squeezing, is known to improve the sensitivity of atomic instruments to static or slowly-varying quantities. Sensing transient events presents a distinct challenge, requires different analysis meth…
View article: Traceable random numbers from a nonlocal quantum advantage
Traceable random numbers from a nonlocal quantum advantage Open
The unpredictability of random numbers is fundamental to both digital security and applications that fairly distribute resources. However, existing random number generators have limitations-the generation processes cannot be fully traced, …
View article: Live magnetic observation of parahydrogen hyperpolarization dynamics
Live magnetic observation of parahydrogen hyperpolarization dynamics Open
Hyperpolarized nuclear spins in molecules exhibit high magnetization that is unachievable by classical polarization techniques, making them widely used as sensors in physics, chemistry, and medicine. The state of a hyperpolarized material,…
View article: Picotesla optically pumped magnetometer using a laser-written vapor cell with sub-mm cross section
Picotesla optically pumped magnetometer using a laser-written vapor cell with sub-mm cross section Open
We demonstrate a sensitive optically pumped magnetometer using rubidium vapor and 0.75 amg of nitrogen buffer gas in a sub-mm-width sensing channel excavated by femtosecond laser writing followed by chemical etching. The channel is buried …
View article: Quantum jump photodetector for narrowband photon counting with a single atom
Quantum jump photodetector for narrowband photon counting with a single atom Open
Using a single neutral Rb87 atom held in an optical trap, and “quantum jump” detection of single-photon-initiated state changes, we demonstrate a single-photon quantum jump photodetector (QJPD) with intrinsically narrow bandwidth and stron…
View article: Live Magnetic Observation of Parahydrogen Hyperpolarization Dynamics
Live Magnetic Observation of Parahydrogen Hyperpolarization Dynamics Open
The entry contains numerical data files, processing code (Wolfram Mathematica) and simulation code (Wolfram Mathematica running the 'SpinDynamica' packages) to generate Figures 1 to 6 of the manuscript titled above, arXiv preprint: https:/…
View article: Telling different unravelings apart via nonlinear quantum-trajectory averages
Telling different unravelings apart via nonlinear quantum-trajectory averages Open
The Gorini-Kossakowski-Sudarshan-Lindblad master equation (ME) governs the density matrix of open quantum systems (OQSs). When an OQS is subjected to weak continuous measurement, its state evolves as a stochastic quantum trajectory, whose …
View article: Functionalized mm-scale vapor cells for alkali-metal spectroscopy and magnetometry
Functionalized mm-scale vapor cells for alkali-metal spectroscopy and magnetometry Open
We describe micro-fabricated rubidium vapor cells with integrated temperature-control functionality and demonstrate their suitability for use in miniaturized ultra-sensitive magnetometers. These functionalized vapor cells (FVCs) embody a d…
View article: Laser-written micro-channel atomic magnetometer
Laser-written micro-channel atomic magnetometer Open
We demonstrate a sensitive optically-pumped magnetometer using rubidium vapor and 0.75 amg of nitrogen buffer gas in a sub-mm-width sensing channel excavated by femtosecond laser writing followed by chemical etching. The channel is buried …
View article: Quantum jump photodetector for narrowband photon counting with a single atom
Quantum jump photodetector for narrowband photon counting with a single atom Open
Using a single neutral 87Rb atom held in an optical trap, and "quantum jump" detection of single-photon-initiated state changes, we demonstrate a single-photon quantum jump photodetector (QJPD) with intrinsically narrow bandwidth and stron…
View article: Spin projection noise and the magnetic sensitivity of optically pumped magnetometers
Spin projection noise and the magnetic sensitivity of optically pumped magnetometers Open
Present protocols for obtaining the ultimate magnetic sensitivity of optically pumped magnetometers (OPMs) utilizing alkali-metal ensembles rely on uncorrelated atoms in stretched states. A new approach for calculating the spin projection …
View article: Traceable Device-Independent Randomness as a Service
Traceable Device-Independent Randomness as a Service Open
We implement a traceable protocol for device-independent random number generation. Our demonstration involves transparently integrating a device-independent RNG into a public randomness beacon, and feeding 7434 random number pulses into th…
View article: Cavity-enhanced detection of spin polarization in a microfabricated atomic vapor cell
Cavity-enhanced detection of spin polarization in a microfabricated atomic vapor cell Open
We demonstrate continuous Pound-Drever-Hall (PDH) nondestructive monitoring of the electron spin polarization of an atomic vapor in a microfabricated vapor cell within an optical resonator. The two-chamber silicon and glass cell contains $…
View article: Telling different unravelings apart via nonlinear quantum-trajectory averages
Telling different unravelings apart via nonlinear quantum-trajectory averages Open
The Gorini-Kossakowski-Sudarshan-Lindblad master equation (ME) governs the density matrix of open quantum systems (OQSs). When an OQS is subjected to weak continuous measurement, its state evolves as a stochastic quantum trajectory, whose …
View article: Quantum-Enhanced Magnetometry at Optimal Number Density
Quantum-Enhanced Magnetometry at Optimal Number Density Open
We study the use of squeezed probe light and evasion of measurement backaction to enhance the sensitivity and measurement bandwidth of an optically pumped magnetometer (OPM) at sensitivity-optimal atom number density. By experimental obser…
View article: Data for: Multi-parameter quantum sensing and magnetic communications with a hybrid dc/rf optically-pumped magnetometer
Data for: Multi-parameter quantum sensing and magnetic communications with a hybrid dc/rf optically-pumped magnetometer Open
This dataset contains data for figures 1, 2, 3, 4, and 5 from the article.
View article: Multiparameter quantum sensing and magnetic communications with a hybrid dc and rf optically pumped magnetometer
Multiparameter quantum sensing and magnetic communications with a hybrid dc and rf optically pumped magnetometer Open
We introduce and demonstrate a hybrid optically pumped magnetometer (HOPM) that simultaneously measures one dc field component and one rf field component quadrature with a single atomic spin ensemble. The HOPM achieves sub-pT/$\sqrt{\mathr…
View article: Inter-species spin-noise correlations in hot atomic vapors
Inter-species spin-noise correlations in hot atomic vapors Open
We report an experimental and theoretical study of spin noise correlations in a $^{87}$Rb-$^{133}$Cs unpolarized alkali-metal vapor dominated by spin-exchange collisions. We observe strong unequal-time inter-species correlations and accoun…
View article: Quantum-enhanced magnetometry at optimal number density
Quantum-enhanced magnetometry at optimal number density Open
We study the use of squeezed probe light and evasion of measurement back-action to enhance the sensitivity and measurement bandwidth of an optically-pumped magnetometer (OPM) at sensitivity-optimal atom number density. By experimental obse…
View article: Anomalous noise spectra in a spin-exchange-relaxation-free alkali-metal vapor
Anomalous noise spectra in a spin-exchange-relaxation-free alkali-metal vapor Open
We perform spin-noise spectroscopy on an unpolarized $^{87}\mathrm{Rb}$ vapor in the spin-exchange-relaxation-free (SERF) regime. We observe noise spectral distributions that deviate strongly from Lorentzian models that accurately describe…
View article: Loophole-free Bell inequality violation with superconducting circuits
Loophole-free Bell inequality violation with superconducting circuits Open
Superposition, entanglement and non-locality constitute fundamental features of quantum physics. The fact that quantum physics does not follow the principle of local causality 1–3 can be experimentally demonstrated in Bell tests 4 performe…
View article: Technology roadmap for cold-atoms based quantum inertial sensor in space
Technology roadmap for cold-atoms based quantum inertial sensor in space Open
Recent developments in quantum technology have resulted in a new generation of sensors for measuring inertial quantities, such as acceleration and rotation. These sensors can exhibit unprecedented sensitivity and accuracy when operated in …
View article: Real-time polarimetry of hyperpolarized $^{13}$C nuclear spins using an atomic magnetometer
Real-time polarimetry of hyperpolarized $^{13}$C nuclear spins using an atomic magnetometer Open
We introduce a method for non-destructive quantification of nuclear spin polarization, of relevance to hyperpolarized spin tracers widely used in magnetic resonance from spectroscopy to in vivo imaging. In a bias field of around 30 nT we u…
View article: Serving Verifiable, Device-Independent Randomness to the Public
Serving Verifiable, Device-Independent Randomness to the Public Open
Device-independent random number generators can be certified unhackable simply by the impossibility of superluminal signaling. We demonstrate a novel protocol to transparently operationalize this security through a public randomness beacon…
View article: USOQS guideline document
USOQS guideline document Open
This document intends to summarize some of the results achieved within the project named Ultra-Stable Optical oscillators from Quantum coherent and entangled Systems (USOQS), to provide a guideline highlighting successes and pit fall we fa…
View article: Quantum jump spectroscopy of a single neutral atom for precise subwavelength intensity measurements
Quantum jump spectroscopy of a single neutral atom for precise subwavelength intensity measurements Open
We present precise, subwavelength optical intensity measurements using a single trapped ^{87}Rb atom as a sensor. The intensity is measured by the scalar ac Stark shift it produces on the F=1→F^{′}=2 hyperfine transition of the D_{2} line,…