Preparing for the Thorium-229 revolution

• Gilad Perez

After a brief introduction related to ultralight (pseudo) scalar dark matter, we shall describe the current status of searches for ultralight dark matter (UDM). We explain why modern clocks can be used to search for both scalar and axion dark matter fields. We review existing and new types of well-motivated models of UDM and argue that they all share one key ingredient - their dominant coupling is to the QCD/nuclear sector. This is very exciting as we are amidst a revolution in the field of dark matter searches as laser excitation of Th-229 with effective precision of 1:10^13 has been recently achieved, which as we show, is already probing uncharted territory of models. Furthermore, Th-229-based nuclear clock can potentially improve the sensitivity to physics of dark matter and beyond by factor of 10^10! It has several important implications to be discussed.

Searching for New Physics with Nuclear Lineshape Data

• Fiona Kirk

The exceptionally low-lying isomer thorium-229m, which had been observed via radioactive decay, was the subject of intense research for several decades, due to its potential as a nuclear clock state. Recently, this state was laser-excited for the first time, bringing us an important step closer to the realisation of nuclear clocks but also opening up new possibilities to search for new physics that couples to the QCD sector. In this talk I will describe how new physics could affect the shape of the nuclear resonance, and explain how already today, nuclear lineshape data can set competitive bounds on ultralight dark matter coupling to the QCD sector, or more generally, on the time-variation of the QCD scale.

Spin-dependent Exotic Interactions: A review

• Lei Cong

A fifth force may arise due to “new physics” beyond the Standard Model. We focus on the spin-dependent fifth forces that are mediated by new particles, such as spin-0 particles (axion and axion-like particles) and spin-1 particles (e.g., light Z’ particle or massless paraphoton). These new ultralight particles are also candidates for dark matter and dark energy, and may also break fundamental symmetries. Spin-dependent interactions between fermions have been extensively searched for in experiments, employing methods such as comagnetometers, nitrogen-vacancy spin sensors, and precision measurements of atomic and molecular spectra. Our research involves a theoretical reassessment of exotic spin-dependent forces. It produces a systematic and complete set of interaction potentials expressed in terms of reduced coupling constants. We conduct an extensive analysis of the existing body of experimental literature on spin-dependent fifth forces, which produces systematic exclusion plots. This leads to a comprehensive understanding of the current research landscape and provide insights for further research.

Quantum limited detection of new physics

• Dan Carney

Many important experiments are now limited by quantum mechanical noise, notably including gravitational wave detectors and axion searches. I will review the basic theory of quantum noise in these systems, and highlight a few ways to get beyond naive quantum limits in order to probe deeper into uncharted parameter space.

A Superconducting Levitated Detector of Gravitational Waves

• Giacomo Marocco

I will describe a proposal to search for gravitational waves (GWs) lying at kHz-MHz frequencies, just outside of the LIGO band. I will introduce how quantum noise limits the sensitivity of opto- and magnetomechanical GW detectors, and explain how a table-top magnetomechanical device can have lower quantum noise at high frequencies than an optomechanical laser interferometer. Such a sensor may have broadband sensitivity to high-frequency GWs produced by a variety of SM and BSM scenarios.

The Ferroaxionic Force

• Amalia Madden

I will demonstrate that piezoelectric materials can be used to source virtual QCD axions, generating a new axion-mediated force. Within a piezoelectric material with aligned nuclear spins, I will show that there is a new, effective in-medium scalar coupling of the axion that can be enhanced by up to 7 orders of magnitude relative to the scalar coupling in vacuum. I will then outline a detection method based on nuclear spin precession induced by the axion’s pseudoscalar coupling to nuclear spins. Using this effect, future experimental setups can be sensitive to the QCD axion in the unexplored mass range from 10^-5 eV to 10^-2 eV.

Gravitational search for dark matter using mechanical sensors

• Gerard Higgins

We are developing ultra-precise mechanical sensors to search for dark matter in the laboratory. These sensors consist of magnetically-levitated superconductors which are monitored using superconducting quantum circuits to achieve exceptional sensitivity. In the near term we plan to probe the existence of wavelike dark matter (e.g. vector B-L dark matter) in unexplored parameter regimes. In the longer term we plan to use an array of these sensors to hunt for ultraheavy Planck-mass dark matter particles, which would impart gravitational impulses on the mechanical sensors. This approach would open a new window onto the exploration of dark matter, since we know that the gravitational interaction between dark matter and ordinary matter exists.

EDM Measurement on Laser-Trapped 171Yb Atoms

• Zeng-Tian Lu

The permanent electric dipole moment (EDM) of the 171Yb atom is measured with atoms held in an optical dipole trap (ODT) [Zheng et al., PRL (2022)]. By enabling a cycling transition that is simultaneously spin-selective and spin-preserving, a QND measurement with a spin-state-detection efficiency of 50% is realized [Yang et al., PRApp (2023)]. A systematic effect due to parity mixing induced by a static E-field is observed, and is suppressed by averaging between measurements with ODTs in opposite directions. The coherent spin precession time is found to be much longer than 300 s. An upper limit on the EDM is determined to be on the order of 10-27 e·cm. Meanwhile, a 171Yb – 173Yb co-magnetometer is under development in preparation for the next-generation measurements [Yang et al., Nat Photon (2024)]. These measurement techniques can be adapted to search for the EDM of 225Ra. This work is supported by the Chinese Ministry of Science and Technology, National Natural Science Foundation of China, and the Chinese Academy of Sciences.

Massive graviton dark matter searches with atom interferometers

• John Carlton

Atom interferometers are a class of quantum sensors capable of making precision measurements in many areas of fundamental physics including gravitational wave and ultra-light dark matter (ULDM) searches. While the sensitivity of atom interferometers to scalar and vector ULDM has been established, spin-2 ULDM models have yet to be fully explored. In this talk I will outline the phenomenology of spin-2 ULDM in atom interferometers and discuss how best to optimise searches by operating multiple experiments in a network. Existing laser interferometer constraints for spin-2 ULDM will be complemented by atom interferometers by probing different mass parameter space and offering a distinct method of detection. Not only will spin-2 ULDM induce a change in the laser phase measured in the interferometer, but will additionally couple directly to the internal energy states of the atoms. Atom interferometers are uniquely sensitive to both effects, which will enhance the limits these experiments will place on spin-2 ULDM and help distinguish these signals from scalar candidates. Work in collaboration with Diego Blas and Christopher McCabe.

Polarization effects resulting from gravitational waves and axions and implications for dark matter haloscopes.

• Camilo Garcia-Cely

Axions and gravitational waves give rise to electromagnetic signals in the presence of external electromagnetic fields. This phenomenon, known as the Gertsenshtein effect, has garnered significant attention recently, fostering a synergy between the communities searching for gravitational waves and axions. In this talk, I will review this effect and discuss an additional aspect of this synergy, highlighting that axion experiments optimized for detecting polarization effects can also serve as probes for gravitational waves.

Violation of the equivalence principle induced by oscillating rest mass and transition frequency, and its detection in atom interferometers

• Jordan Gue

We present a theoretical investigation of the expected experimental signals produced by freely falling atoms with time oscillating mass and transition frequency. These oscillations could be produced in a variety of models, in particular, models of scalar dark matter nonuniversally coupled to the standard matter such as axionlike particles and dilatons. Performing complete and rigorous calculations, we show that, on one hand, two different atomic species would accelerate at a different rate, and, on the other hand, they would produce a nonzero differential phase shift in atom interferometers (AI). The former would produce observable signals in equivalence principle tests like the recent MICROSCOPE mission, and we provide a corresponding sensitivity estimate, showing that MICROSCOPE can reach beyond the best existing searches in the axionlike particle case. We also compare the expected sensitivity of two future AI experiments, namely the AION-10 gradiometer and an isotope differential AI considered for MAGIS-100, that we will refer to as SPID. We show that the SPID setup would be more sensitive to these dark matter fields compared to the gradiometer one, assuming equivalent experimental parameters.

We live in interesting times… (Many ways to look for new physics.)

• Dmitry Budker

The times are interesting because we do not understand several basic things about the universe; however, we do not suffer from the lack of ideas of how to go about this. In the process the boundaries between disciplines such as atomic, particle, nuclear, solid-state physics, observational cosmology, etc., are dissolving, which makes it particularly exciting. In this talk I will give a broad overview of experiments, recently completed, ongoing and planned, that our group and collaborators are involved in. Sensors (of, course, quantum!) are at the center of everything.

Quantum Sensing for High Frequency Gravitational Waves

• Sebastian Ellis

We will examine the requirements needed for a sensitive gravitational wave detector at high frequencies. The sensitivity can be factored into one generic quantity and a detector-specific transfer function. We will then survey various recent proposals for such detectors, taking account of their transfer functions. The challenges of detecting high frequency gravitational waves will be made apparent, along with the benefits of going beyond the standard quantum limit.

Superradiant interactions of cosmic noise

• Asimina Arvanitaki

In this talk, I will describe three things. First, I will outline the conditions under which the interaction rate of inelastic processes that change the internal state of a system of N targets scales N2.This is an effect distinct from coherent elastic scattering, but with the same scaling. These inelastic processes are a generalization of Dicke superradiance for light, and we thus refer to them as superradiant interactions. Second, I will present example rates for such processes for various weakly interacting particles, namely, the cosmic neutrino background, axion and dark photon dark matter, as well as reactor, solar and bomb neutrinos. The rates we find can be quite sizable on macroscopic yet small targets. For example, the CνB interacts with a rate of O(0.1 Hz) when scattering off a 10 cm liquid or solid-state density spin-polarized sphere, a 21 order of magnitude enhancement compared to the incoherent inelastic contribution. Finally, I will discuss how superradiant interactions manifest as a source of noise on a system, which points to potential quantum observables for these processes that go beyond traditional energy exchange.

Axion dark matter detection with exotic phases of matter

• Christina Gao

Optimal Quantum Control for Precision Frequency Measurements

• Yonatan Kahn

I will give a pedagogical review of optimal quantum control schemes developed to push frequency measurements beyond the Standard Quantum Limit. I will discuss an application of this scheme to axion detection using the homogeneous precession domain of superfluid helium-3.

Optically-trapped membranes for high-frequency gravitational wave detection

• Christoph Reinhardt

Over the past two decades, nanomechanical membrane resonators have emerged as a versatile platform for quantum motion experiments and ultra-low-noise sensing. Recent advances in their performance have brought them close to sensitivity levels that promise significant contributions to the search for new fundamental physics. This presentation will provide a brief overview of membrane resonators and introduce a novel concept for a membrane-based high-frequency gravitational wave detector. The proposed instrument leverages the technique of optically trapping a membrane within an optical cavity. Finally, I will discuss the potential for achieving sensitivities compatible with detecting signals originating from neutron star mergers in the kHz range, as well as from predicted phenomena such as axion superradiance of astrophysical black holes in our galaxy, reaching into the tens of kHz.

Probing new physics with open quantum systems

• Christian Kading

Essentially, every realistic quantum system is open, which means that it is interacting with another system that we call an environment. An effective description of open systems leads to predictions of effects like decoherence or frequency shifts. In this talk, I will present a recently developed first principle-based formalism for describing open systems in quantum field theory. Subsequently, I will discuss how it predicts open quantum dynamical effects that can be used to probe physics beyond the standard models of particles and cosmology in modern quantum experiments. In particular, I will show that frequency shifts induced by hypothetical scalar fields in atom interferometry experiments have the potential to put new constraints on some popular scalar field models.

Quantum Sensors for New-physics Discoveries in the Laboratory and in Space

• Marianna Safronova

The extraordinary advances in quantum control of matter and light have been transformative for development of quantum sensors enabling probes of the most basic laws of Nature to gain a fundamental understanding of the physical Universe. Exceptional versatility, inventiveness, and rapid development of precision experiments supported by continuous technological advances and improved atomic and molecular theory led to rapid development of many avenues to explore new physics. I will give an overview of searches for physics beyond the standard model (BSM) with AMO-based quantum sensors and focus on dark matter searches with atomic and nuclear clocks and new ideas for BSM searches with quantum sensors in space. I will also discuss quantum algorithms that can aid dark matter searches. In conclusion, I will describe new efforts in developing a roadmap for terrestrial very-long-baseline (km-scale) atom interferometry for gravitational wave and dark matter detection.

Gravitational sensing of ultralight dark matter

• Hyungjin Kim

Ultralight dark matter exhibits two types of density fluctuations: coherent and stochastic. Since those fluctuations appear in the different frequency range, the existence of two modes of fluctuations offer a way to probe a wide range of mass of ultralight dark matter, even within a single detector setup. In this talk, I will discuss a few ways to probe ultralight dark matter around the solar system with gravity wave detectors. I will show that current and future gravity wave detectors are capable of probing a few hundred to thousands times local dark matter density near the solar system, which provides one of the best ways to test dark matter at this small scale.

QSNET: A network of clocks for measuring the stability of fundamental constants

• Laura Blackburn

I will discuss the QSNET project, that is building a network of atomic and molecular clocks in the UK to achieve unprecedented sensitivity in testing variations of the fine structure constant, α, and the proton-to-electron mass ratio, μ. This in turn will allow us to either discover that fundamental constants are actually not constant, or to provide more stringent constraints on a wide range of fundamental and phenomenological “new physics” models. These include models of dark energy, ultra-light dark matter and grand unification models. The project currently includes the National Physical Laboratory, the University of Sussex, the Imperial College London, the University of Birmingham, and several international partners.

QUEST-DMC: Sub-GeV Dark Matter Searches

• Neda Darvishi

In this talk, the potential for detecting sub-GeV dark matter through the QUEST-DMC experiment will be explored. The experiment employs a novel approach, utilising superfluid Helium-3 (He-3) alongside quantum sensors. Superfluid He-3 is highlighted as an optimal medium for sub-GeV dark matter searches, particularly effective in spin-dependent interactions. The presentation will cover the projection sensitivity to diverse dark matter models.

Precision measurement with atom interferometry

• Chris Overstreet

Light-pulse atom interferometers, which use lasers to separate and interfere atomic wave packets, are sensitive probes of inertial and gravitational forces. In this talk, I will outline the key concepts that underlie this experimental technique. I will also discuss several applications of atom interferometry for fundamental physics, including tests of the equivalence principle, measurements of fundamental constants, gravitational wave astronomy, and searches for dark matter.

Novel computational perspectives on matter-wave interferometry

• Leonardo Badurina

Abstract: Matter-wave interferometry holds promise as a powerful quantum sensing technique for fundamental physics. From a theoretical standpoint, it is essential to identify the observables that can be accessed experimentally and compute signatures from phenomena of interest in a tractable and consistent manner. In this talk, I will present two novel approaches that achieve this: one for computing general relativistic effects in atom gradiometers, and another for calculating coherently enhanced collisional signatures in multi-particle interferometers. I will show how these formalisms provide a streamlined and transparent method for studying the signatures of gravitational waves and dark matter in matter-wave interferometers. Additionally, I will explain how these frameworks shed light on the similarities and differences between matter-wave interferometers and other detectors, such as laser interferometers and dark matter direct detection experiments.

Probing new hadronic interactions with exotic atoms

• Omer Shtaif

Atomic spectroscopy is a prominent tool for probing new physics as well as testing the standard model of particle physics. A key factor in atomic systems is the average distance between the nucleus and the orbiting particle, which greatly determines the sensitivity to the range of interactions. We study a class of atomic systems that, on the one hand, have small Bohr radii, thus increasing the sensitivity to short-range interactions mediated by heavy new bosons and, on the other hand, their angular momentum is maximal which considerably reduces the effect of contact terms such as those arising from the strong nuclear force and finite-size corrections. We discuss overlooked effects of standard model finite-size corrections focusing on the nuclear polarizability effect, and how to bypass it in a new physics search. Finally, we set new terrestrial bounds on several benchmark models.

Recoil measurement with single-photon transitions

• Jesse Schelfhout

Atom interferometry measurements of the recoil of an atom upon absorption/emission of a photon are used in some of the highest-precision tests of the Standard Model via the fine-structure constant. Current experiments use multi-photon transitions with Rb and Cs, but there is a tension between the best values from each species. In this talk, I will present a scheme for performing recoil measurements with single-photon transitions. I will discuss some of the systematics important for reliably determining the fine-structure constant, including laser wavefront quality and light shifts, and how they might be addressed in upcoming experiments. These techniques would be well-suited to upcoming large-scale atom interferometry experiments with Sr or Yb, such as AION, MAGIS, and VLBAI.

Electron(s) in a Penning Trap for Tests of the Standard Model

• Xing Fan

I will present the recent measurement of the electron Magnetic Dipole Moment, known as the g-factor. The new measurement tests the most precise prediction of the Standard Model (SM). Key techniques include an isolated electron in a Penning ion trap, cooling to its quantum ground state, quantum non-demolition detection, and controlling cavity-QED systematic shifts. I will describe how the ideal environment is realized, along with the effort for improved measurement, matter-antimatter symmetry tests, and other applications for fundamental physics.

Cesium in Cryogenic Matrices: Towards a Measurement of the eEDM

• Sebastian Lahs

To answer the open questions in the fundaments of physics, new theories that reach beyond the standard model of particle physics are needed. Many of these predict a nonzero electron electric dipole moment (eEDM). While over the last decades, measurements in atomic and molecular beams and ion traps provided the most successful eEDM searches, only quite recently did the method of matrix isolation spectroscopy arise. It has the potential advantage of performing spectroscopy on unprecedented numbers of atoms/molecules. To perform such a measurement in the future, it is necessary first to understand how the trapping of atoms inside the cryogenic matrix looks in detail. In this contribution, I present what we learned so far through experiments and simulations of cesium trapped in inert argon and parahydrogen matrices.

Precision measurement with molecules containing deformed nuclei

• Nick Hutzler

Molecules are sensitive probes of fundamental symmetry violations in both electrons and nuclei. A heavy, deformed nucleus can amplify signatures of exotic nuclear effects, and an engineered molecular structure can provide a platform for quantum control with robustness against experimental errors. We are performing experiments with YbOH, which has a quadrupole-deformed nucleus which enhances the nuclear magnetic quadrupole moment (MQM), and RaOH, which has an octupole-deformed nucleus which enhances the nuclear Schiff moment (NSM). In this talk, I will give an update on the status of these efforts, including production and spectroscopy of RaOH, coherent control in YbOH, and approaches to engineer enhanced coherence in these and other molecules.

Quantum Metrology with Molecules in an Optical Lattice

• Tatsam Garg

Ultracold molecules have recently drawn widespread interest as exquisite platforms for precision measurements to probe fundamental physics. In particular, the internal structure of molecules with a heavy nucleus, large electric dipole moment, and several bosonic and fermionic isotopologues leads to vastly improved sensitivities to symmetry-violating physics. The current generation of precision measurement experiments is using fast cryogenic molecular beams, and thus, is significantly limited in the achievable duration of coherent measurement and degree of quantum state control. The natural next step is to borrow the techniques of atomic laser cooling and trapping, and extend them to molecules. While the rich internal structure complicates this realization in heavy dipolar molecules, particularly in fermionic species with complex hyperfine structure, there has been significant progress towards this goal over the last two decades. Building upon these advances, we are building a precision metrology platform by laser cooling and trapping different isotopologues of barium monofluoride (BaF) molecules in an optical lattice to study symmetry-violating physics. While trapping and ultracold temperatures will allow for record-long coherence times and better control over the internal quantum states, the ability to switch between different bosonic and fermionic isotopologues will enable access to varying scenarios of symmetry violations. The techniques developed in this project are advancing us in the direction of achieving denser ensembles of ultracold heavy molecules where interactions begin to play a crucial role, and thus, facilitating sensing schemes that use entanglement to surpass the standard quantum limit, paving the way to true quantum metrology with molecules.

Closing Remarks