In this colloquium, I will present two of my research projects in atomic, molecular, and optical physics. The first project deals with the measurement of fully momentum analyzed projectiles and D⁺ fragments produced in p + D₂ collisions in coincidence. From the data, we extracted fully differential cross sections (FDCS) for vibrational dissociative capture as a function of projectile scattering angle θ_p. A pronounced molecular two-center interference pattern was observed. It is due to indistinguishable projectile diffraction from the two atomic centers of the molecule. Earlier, we found a similar interference pattern for p + H₂ collisions. One important difference between our results for the H₂ and D₂ targets is that in the former case, the phase shift was found to be scattering angle (θ_p) dependent, while in the latter case, the phase shift was constant at π. So far, we could only offer a hypothetical explanation for the phase shift observed in vibrational dissociation for an H₂ target and the difference to the D₂ target.

The seminar will present an overview of Oklo reactor technology and current development activities and planned deployments. Oklo is deploying the Aurora Powerhouse reactor - a sodium-cooled fast reactor (SFR) based on the legacy of the EBR-II and FFTF SFRs constructed and operated under the Department of Energy. Oklo is building a unique, vertically integrated business model that includes fabricating and recycling its own HALEU fuel - a uranium/zirconium metal alloy design. Oklo also intends to recycle and fabricate fuel from existing LWR spent fuel and surplus nuclear materials

Quantitative measurements of physical, chemical, and biological variables that retain the local environmental context are critical for diverse oceanographic applications spanning chemical sensing to water security. However, many current methods of physical, chemical, and biological analysis face tradeoffs in sensitivity, portability, and scalability. In this talk, I will describe examples from my research tackling these challenges by controlling the interaction between light and matter at the nanoscale through nanophotonics and materials engineering.

The Godfather of the Li-Ion Battery, Sir Stan Whittingham, will be at NPS on Monday, 23 February to give a talk on The First Half Century of Lithium Batteries and the Challenges Faced in Building an American Industry.  His visit is being sponsored and supported the EAG, in coordination with the Physics Department.

The success of the nuclear industry abroad relies on the success of implemented nonproliferation measures within facilities that handle nuclear materials. Between rising global tensions between nuclear powers and their allies and the advent of novel reactor designs such as molten salt reactors that bear striking similarities to pyroprocessing methods, the need for instrumentation that can reliably differentiate the isotopic signatures associated with civilian nuclear use and those associated with weapons production is imperative for ensuring compliance with international agreements. In this talk, I will overview the history of the instrumentation used to rule out destructive intent of nuclear material and describe recent developments in nonproliferation technologies. From here, I will describe how my work on instrumentation based on laser spectroscopy may aid this mission thanks to relatively low measurement times, sensitivity across elements and phases, and compatibility with in-situ measurements. Specifically, I will discuss studies optimizing isotopic measurements in uranium hexafluoride gas using laser-induced breakdown spectroscopy (LIBS) and how LIBS could be implemented in molten salt reactor environments.

Atoms are the most natural quantum sensors. They have been at the heart of precision measurement experiments thanks to our exquisite understanding of light-atom interactions and quantum control. In this talk I will discuss our current applications of the current status of hot atom-based sensors and potential quantum enhancement of their performance, and will present some recent results on applications of atomic magnetometry and electrometry for charged particle beam and plasma diagnostics.

The control and manipulation of electromagnetic (EM) waves have long been the focus of academic research and industry. Novel methods of redirecting, filtering, modulating, attenuating, and radiating waves have been developed and applied to a wide range of applications in wireless sensing, communication, radar, space, and naval systems. In addition to traditional antennas and microwave devices, a new generation of engineered materials, i.e., metamaterials, has recently enabled properties such as negative refraction and near-zero permittivity that are not achievable in natural or previously synthesized media. Researchers have also designed photonic and plasmonic structures that provide exotic forms of EM wave control. In this presentation, a selection of our recent activities in this area will be covered.

Einstein is not typically associated with intrigue and mystery, but the FBI initiated an investigation of Albert Einstein in 1932 and the investigative file was maintained until just before his death in 1955. This talk will review the reason the case was initiated, the investigative steps taken during the case, the complications faced by the investigators, the historical context of the case, and the ultimate conclusion of the matter. We will also review the divergent opinions of two separate historians regarding the question of Einstein’s adjacency to communist spies and operatives. United State counterintelligence concerns regarding communist activity in the United States was not constrained to the era of McCarthyism. The FBI’s file regarding Einstein and others like it provides a chance to reflect on how national security concerns and the advancement of science occasionally conflict.

The search for dark matter and for new sources of gravitational waves offers potentially revolutionary opportunities to learn about the fundamental properties of the Universe. Strong astrophysical evidence indicates that dark matter makes up most of the matter in the Universe, yet its nature remains a great mystery. The detection of gravitational waves in currently unexplored frequency ranges could provide unique insights into astrophysics and cosmology. In this colloquium, I will discuss two emerging techniques for probing dark matter and gravitational waves. The first method involves precise optical comparisons of the lengths of cryogenic, vibration-isolated optical resonators. I will discuss the results from the first dark matter search using this approach, as well as prospects for using this method for high-frequency gravitational wave detection. The second method, long-baseline atom interferometry, involves the coherent splitting of the wavefunctions of atoms over large distances and the subsequent observation of interference of the recombined wave packets. I will introduce MAGIS-100—a 100-meter-tall atom interferometer currently under construction at Fermilab—and describe experimental demonstrations of a new approach to atom interferometry that paves the way for long-baseline atom interferometers to reach their full scientific potential.

Full quantum-mechanical treatments of light-matter interaction result in a rich phenomenology of quantum entanglement that only in the last few decades we are starting to fully appreciate. For light scattering, the formation of collective entangled states on atomic ensembles is heralded by detection of photons spontaneously emitted by the sample. Its origin is the coherent interaction of atoms with the quantum reservoir of vacuum modes. In the last two decades, many groups have explored this process to devise applications in quantum information. Here I present the recent work of my group on the problem, exploring quantum correlations generated from simple systems, like ensembles of two- and three-level atoms. I particularly discuss the peculiar position of this problem on the backdrop of the broad discussion about the role of quantum entanglement in our macroscopic world. Finally, I review how these correlations may be used to build quantum networks and comment on the perspectives of this field in Brazil.

Ultra-cold quantum gases promise to boost the sensitivity and accuracy of inertial matter-wave interferometers. Applications of these sensors extend from fundamental physics over the use in navigation to interdisciplinary applications such as geodesy. Space is a unique environment for sounding out the ultimate precision of these sensors, which might be beneficial for e.g. satellite gravimetry. Exploiting quantum gases for high-precision interferometry places high demands on their control and manipulation. We take benefit of various microgravity platforms such as the Bremen drop tower, the Einstein elevator in Hannover, sounding rockets and the international space station to advance the necessary methods. The DLR-mission MAIUS-1 demonstrated Bose-Einstein condensation and performed first interferometry experiments during the space travel of a sounding rocket. NASA’s Cold Atom Laboratory continues this research in orbit on the ISS.

Starting from a rubidium Bose-Einstein condensate, recently lowest expansion energies have been achieved by us in the Bremen drop tower as required for extending atom interferometry over several seconds. These quantum-gas sources reach the performance as required for inertial quantum sensors proposed for satellite gravimetry. Indeed, the EU project CARIOQA-PMP develops an engineering model taking heritage of our source concept for a pathfinder mission towards quantum-sensor based satellite gravimetry.

The Nuclear Science and Engineering Research Center is a Defense Threat Reduction Agency office that supports interdisciplinary project across the C-WMD enterprise. This colloquium is aimed to increase the awareness of DTRA, its contribution to Strategic Deterrence, and how NPS Faculty and Students can become more involved in DoD research problems centered around C-WMD topics.

This talk will discuss the basic continuum approach we use to describe and model granular materials from a homogenized (as opposed to grain-by-grain) perspective. The goal will be to determine a modeling framework able to simultaneously describe the various phases of matter that granular media assumes --- solid-like (dense with yield stress), liquid-like (dense flowing), and gas-like (separated grains). The talk will begin with a careful review of the broad continuum principles involved, including stress tensors, deformation kinematics, balance relations, and constitutive relations. We will discuss the various challenges researchers have had in rigorously describing granular media's constitutive behavior, i.e. the general deformation response to applied load. To that end, I will introduce a hierarchy of constitutive models for granular media, which add progressively more detail into the modeling and accuracy into the predictions. These models will be demonstrated as will their modern numerical implementation methods.

Abstract: Quantum state engineering, many-body physics, and laser technology are helping to increase the size of coherent quantum systems and revolutionize the performance of atomic clocks and metrology.  A quantum gas of strontium atoms loaded into arrays of optical traps represents such a system that combines the best measurement precision and accuracy. Recent advances include precise engineering of a spin Hamiltonian to achieve a record clock accuracy, determination of the gravitational time dilation across a few hundred micrometers, and employment and verification of spin entanglement for clock comparison. These progresses in quantum metrology provide new insights into dynamical phases of matter, and raise the prospect of using the next generation of clocks to search for new physics beyond the minimal standard model and probe the interface of gravity and quantum mechanics. 

Abstract: Atomic clocks realize the most accurate measurements of any physical observable, determining the frequencies of atomic transitions to a part in 10¹⁸. They exploit the high-coherence central to atomic physics that underlies many applications, from clocks and atom interferometry to quantum information processing. I will describe how atomic clocks tick and discuss several general interest physics aspects of modern microwave and optical frequency atomic clocks. These include quantum mechanical collisions at microKelvin temperatures, frequency shifts due to microwave photon recoils, laser-cooling of cadmium for optical lattice clocks, tests of Beyond Standard Model physics using isotope shifts, and tests of general relativity with orbiting atomic clocks.

Abstract: Air-sea interaction processes define many prominent features of the acoustic ambient noise spectrum in the ocean (Wenz, 1962). Therefore, underwater acoustic field measurements have demonstrated a substantial potential in monitoring wind speed over the ocean. Shaw et al. (1978) pioneered the field by establishing a linear relationship between the underwater sound pressure levels and the logarithm of low to moderate local wind speeds. Later, Wilson and Makris (2006) further advanced the theory by proposing a parameterized acoustic notional surface source model specifically designed to estimate high wind speeds during tropical cyclones.  However, even in the Gulf of Mexico region, that is heavily impacted by hurricanes, acoustic data input is not routinely used to track cyclones’ wind speeds. The talk will discuss several approaches to the analysis of the acoustic data collected by the bottom-anchored passive acoustic monitoring system during storm Barry (2019) in the Gulf of Mexico to estimate local wind speeds. The estimated wind speeds are compared to the high-resolution ones generated by the Weather Research and Forecast model. Recently, underwater gliders equipped with passive acoustic systems in addition to traditional set of environmental sensors have been emerging as a new tool for understanding the marine conditions that influence the onset and amplification of tropical cyclones. In this context acoustic data could aid in refining wind strength forecasting, thereby aiding in high spatial resolution wind mapping during hurricanes. Fully autonomous glider’s reconnaissance may also offer a new type of field data (acoustic) to integrate into the operational weather forecasting models used by NOAA and U.S. NAVY for more reliable cyclone strength prediction. [Research supported by the Office of the Under Secretary of Defense for Research and Engineering, award# FA9550-21-1-0215]

Abstract: The extreme precision and accuracy of state-of-the-art optical atomic clocks can be used to look for very small deviations from the predictions of the Standard Model, offering a tool to search for beyond Standard Model (BSM) physics complementary to particle accelerators.  These searches are based on measuring the frequency ratio of two transitions that depend differently on interactions with BSM particles or fields.  In this talk, I will begin with a brief review of optical atomic clocks, focusing on clocks based on quantum-logic spectroscopy of Al+.  I will proceed to present a frequency ratio measurement between Al+ and Yb clocks at NIST that used a new coherent clock comparison protocol called differential spectroscopy in order to achieve the highest precision of any interspecies ratio measurement to date.  I will conclude with a discussion of two new experiments being set up at UCLA aimed at performing precision quantum-logic spectroscopy of transitions with much higher sensitivity to BSM physics in a variety of sectors.  In the first, precision measurements of the 149 nm nuclear isomer transition in sympathetically laser cooled 229Th3+ ions will be used to search for proposed ultralight scalar dark matter models such as the relaxion and for time-variation of the fundamental constants predicted by theories that seek to unify general relativity with quantum mechanics.  In the second, quantum control and quantum-logic spectroscopy of polyatomic molecules will be used to study and search for fundamental symmetry violations in the weak and strong force sectors.

Abstract: Flow noise (i.e., acoustic noise generated by turbulent flow) is one of the major sources of noise of naval platforms and remains one of the main challenges for acoustic signature management (due to ever-increasing operational speed and reduction of noise level generated by other sources). It has been well recognised that a simple yet reliable prediction methods of flow noise at the initial stage of the future underwater platforms design and development is a critical success factor for large acquisition projects.

Any experimental study of flow noise is a rather difficult and often expensive undertaking involving complex large-scale experimental facilities. This is due to the fact that this phenomenon is often masked by extraneous noise entering or generated by the experimental facility.

We present a review of our recent experimental investigation of flow noise with a small-scale buoyancy driven model in DST Group’s Large Water Tank and in the acoustic enclosure in DST Group’s Wind tunnel. The uncertainties associated with the upscaling procedure for the results of small-scale modelling are also discussed. The talk is intended for a general audience.

Abstract: The phenomenon of resonance underlies a myriad of important features (both desirable and unwanted) across physics and engineering. This talk will present a brief survey of examples followed by a couple of recent developments. The first involves the use of 3D-printing to illustrate sympathetic resonance – via a useful teaching tool. The second concerns the prediction of critical speeds (a resonant condition) in rotation shafts – an example of non-destructive testing. The talk is intended for a general audience.

Abstract: The remarkable precision of optical atomic clocks offers sensitivity to new and exotic physics through tests of relativity, searches for dark matter, gravitational wave detection, and probes for beyond Standard Model particles. While much of optical clock research has focused on improving their absolute accuracy, many searches for new physics can be performed with relative comparisons between clocks. To this end, we have recently realized a “multiplexed” strontium optical lattice clock consisting of two or more clocks in one vacuum chamber, forming a miniature clock network. This enables us to bypass the primary limitations to typical atomic clock comparisons and to achieve new levels of precision. 

In this talk I will explain the motivation, concept, and operating principles of our multiplexed optical lattice clock. I will then present recent experimental results in which we performed a novel, blinded, precision test of the gravitational redshift with a vertical array of 5 evenly-spaced ensembles of ultra-cold strontium atoms spanning a total height difference of 1 cm. I will present the error budget produced from our systematic evaluation, and the unblinded results of our first test. I will explain how these results can also be viewed as proof-of-principle measurements of relativistic gravitational potential differences at the millimeter scale, with applications to geodesy. Finally, I will discuss the outlook for using our apparatus for future searches for new physics, including a novel direct test of the Einstein Equivalence Principle, and explorations of the interplay between general relativity and quantum mechanics. 

Note: Classification Level: SFRD. This talk will be classified Secret.

Abstract: While Cold War deterrence scenarios often revolved around large-scale nuclear exchanges between the US and the Soviet Union, the new multipolar scenario is more likely to have to deal with limited exchange scenarios born out of ongoing regional and/or theater conventional conflict. To make the situation even more complex, these situations may now also arise in the context of two peer competitors as opposed to the single peer competitor faced during the Cold War. From this backdrop a new series of deterrence scenarios and attendant challenges arise, requiring different thinking at both the policy/strategy level as well as different options generated from the weapons technical community. This talk will explore this interaction between policy/strategy and technical options, including several options that go beyond the typical technical developments the nuclear security enterprise has focused on during recent decades.

Abstract: Development of new optoelectronic materials and architectures is required to drive innovation in photonic sensing, particularly those that expand our ability to see through degraded atmospherics and support real-time processing. This talk will overview efforts at Crane to develop multiphysics models of low-dimensional materials, such as quantum nanocrystals, as novel infrared focal planes and design novel imaging optics using, e.g., dielectric metasurfaces. Opportunities for faculty and student engagement with NSWC Crane will be highlighted.

Thin film lithium niobate (TFLN) photonic integrated circuits offer several improvements over other platforms in terms of material loss, energy efficiency, and operational bandwidth, making them promising enablers for high data rate optical communication. We review our recent demonstration of quadrature phase shift keying in an ultrasmall TFLN photonic crystal-based IQ modulator. Our modulator features a footprint of 40 × 200 μm² along with quality factors approaching 10⁵ providing it with a V_π = 1.16 V [H. Larocque et al. CLEO 2023, paper STh1R.3; H. Larocque et al. arXiv:2312.16746]. We discuss an extension to and optimization of quadrature amplitude modulation encoding schemes tailored to the device’s voltage response, including the use of a deep neural network for streamlining bit error rate minimization.

The storage of electrical energy, and its delivery as power pulses, plays an important and growing role in many Navy applications. These include stabilization of electrical grids and high-power sources for radars, lasers, microwaves, electromagnetic launch of aircraft or missiles, and railguns. Navy requirements are at sea, land, air, space, under sea, and for expeditionary forces, some of which in common with Army, Air Force, and Space Command missions.

What is a quantum computer and what might it be useful for? I'll describe how a quantum computer, based on superconducting qubits, works. I'll also describe fault tolerant quantum computing (FTQC), and the applications where a quantum computer might vastly outperform even the largest high performance computing facility. What might such "utility-scale" quantum computer look like and how big would it have to be to solve problems intractable on today's machines?