We report on how to use a frequency approach to analyze Atomic Clock Ensemble in Space (ACES) space-clock to ground comparison data to constrain the gravitational-redshift violation parameter α to less than 2.9 × 10 − 6 from 12 d of simulated data. Previous work on this extrapolation achieved similar precision only with a phase approach; our method uses a frequency observable derived directly from the phase observable, avoiding the need to fit random walk data or perform Monte Carlo simulations to determine the fit uncertainty. Our approach not only results in similar α uncertainty for 12 d of simulated data but also offers new analytic expressions for how the uncertainty scales with data-length and a different framework for understanding the limits of the measurement. The new framework illustrates more readily how a 1 × 10 − 16 frequency offset between the space and ground clock leads to a bias (i.e. systematic uncertainty) in α comparable to its statistical uncertainty of 2.9 × 10 − 6 . Overall, our approach provides an independent analysis method for the determining α , particularly important for the overall rigor and validity of the ACES science return.

The DESIRE project aims to test chameleon field theories as potential candidates for dark energy. The chameleon field is a light scalar field that is subject to screening mechanisms in dense environments making them hardly detectable. The project is designed to overcome this challenge. To this end, a specially designed source mass generates periodic gravitational and chameleon potentials. The design of the source mass allows for adjustment of the amplitude and periodicity of the gravitational potential while keeping the chameleon potential unchanged. The periodicity of the potentials makes them distinguishable from the environment and allows for resonant detection using multiloop atom interferometry under microgravity conditions.

The development of quantum technology is facing substantial scientific and technological challenges. More importantly, there are as-yet-unknown aspects and applications of quantum technology to be uncovered. There is thus global acknowledgement by stakeholder communities and governments alike that the ongoing advancement of quantum science and technology ought to be an international pursuit in which the strain between competition and cooperation is balanced through collaboration. It is in this spirit of “coopetition” that this article seeks to give a cross-sectional view of the state of Quantum 2.0 technology in the USA, Europe and Japan, by providing the predictions of a large number of experts concerning progress in quantum technology over the next two decades.

Precise control of atomic systems has led to an array of emerging ‘quantum’ sensor concepts ranging from Rydberg-atom RF-electric probes to cold-atom interferometer gravimeters. Looking forward, the potential impact of these technologies hinges on their capability to be adapted from laboratory-scale experiments to compact and low-power field-deployable instruments. However, existing setups typically require a bulky and power-hungry laser and optics system (LOS) to prepare, control, and interrogate the relevant atomic system using a variety of frequency-referenced and rapidly reconfigurable laser beams. In this work, we investigate the feasibility of using semiconductor optical amplifiers (SOAs) to replace high-power pump lasers and acousto-optic modulators within a simple atom cooling apparatus, looking forward to the ultimate goal of a space-deployable atom interferometer. We find that existing off-the-shelf SOA components operating at relevant wavelengths for Cs and Rb atom cooling (852 and 780 nm, respectively) are able to permit an attractive combination of rapid (sub-microsecond), high extinction ratio (>60-65 dB) switching while acting as power boosters prior to the atom physics package. These attributes enable a radically different, power-efficient approach to LOS design, reducing or eliminating the need for Watt-class laser amplifiers that are unsuitable for flight deployment. Building on these results, we construct a simple and compact all-semiconductor laser/amplifier LOS for atom cooling that is integrated with custom path-to-flight drive electronics. Up to 125 mW of total optical power is delivered to six fiber-coupled channels for magneto-optical-trap-based cooling of a cloud of neutral Cs atoms. The entire LOS, including reference and cooling laser subsystems and control electronics, occupies a volume of 20×20×15 cm and totals DC power consumption of around 13.5 W, and is designed in a modular format so that additional hardware for synthesizing atom interferometry beams may be added through future development efforts. These results indicate the utility of all-semiconductor laser systems for future low-power flyable atom-based sensor instruments.

A quantum gravity gradiometer in a low Earth orbit, operating in a cross-track configuration, could be a viable single-spacecraft measurement instrument to provide mass change data for Earth observation, at comparable or better resolutions to existing maps generated by GRACE-FO. To reach the sensitivity for these science-grade measurements, many parts of the cold-atom interferometer need to be operating at, or beyond, state-of-the-art performance. In order to raise the maturity of the technology of the cold-atom gradiometer and determine the feasibility of a science-grade instrument, a pathfinder technology demonstration platform is funded. The requirements and a notional design for such a pathfinder and the outstanding challenges for science-grade instruments are presented.

Integrated with novel micro-fabricated technologies, the micro mercury trapped ion clock (M2TIC) prototypes can reach the 10^?14-stability level in one day with size, weight, and power (SWaP) of 1.1 L, 1.2 kg, and under 6 W of power. The low-SWaP, high-performance combination makes M2TIC an attractive candidate for modern positioning, navigation, and timing (PNT) applications. For operational clocks in real-world applications, reliable long-term operation is just as important. Here we demonstrate that an M2TIC prototype clock continuously operated for over 240 days. The clock package temperature was varied between 30oC to 53oC. These results demonstrate the robustness of the M2TIC technology and pave the way towards operational clock products.

Tetrahedral configurations of spacecraft on unperturbed heliocentric orbits allow for highly precise observations of small spatial changes in the gravitational field, especially those affecting the gravity gradient tensor (GGT). The resulting high sensitivity may be used to search for new physics that could manifest itself via deviations from general relativistic behavior yielding a nonvanishing trace of the GGT. We study the feasibility of recovering the trace[GGT] with the sensitivity of O & eth; 10 - 24 s - 2 & THORN;- the level where some of the recently proposed cosmological models may have observable effects in the Solar System. Specifically, we consider how a set of local measurements provided by precision laser ranging (to measure the intersatellite ranges) and atom-wave interferometry (to correct for any local nongravitational disturbances) can be used for that purpose. We report on a preliminary study of such an experiment and on the precision that may be reached in measuring the trace[GGT], with the assumption of dragcompensated spacecraft by atom interferometer measurements. For that, we study the dynamical behavior of a tetrahedral formation established by four spacecraft placed on nearby elliptical orbits around the Sun. We develop analytical models for the relevant observables and study the conditions for setting up an optimal tetrahedral configuration. We formulate the observational equations to measure the trace[GGT] relying only on the observables that are available within the formation, such as those based on the laser ranging and the Sagnac interferometry. We demonstrate that the Sagnac observable is a mission-enabling capability that allows us to measure the angular frequency of the tetrahedral rotation with respect to an inertial reference frame with an accuracy that is much higher than that available from any other modern navigational techniques. We show that the quality of the science measurements is affected by the tetrahedron evolution, as its orientation and the shape change while the spacecraft follow their orbits. We present the preliminary mission and instrument requirements needed to measure the trace[GGT] to the required accuracy and thus demonstrate the feasibility of satisfying the stated science objective.

NASA’s Cold Atom Laboratory (CAL) is a multi-user science facility for studying quantum gases in the microgravity environment of the International Space Station. The persistent microgravity environment of the ISS enables research with ultracold atoms in a temperature regime and force-free environment inaccessible to terrestrial laboratories, unlocking the potential to observe novel quantum phenomena. CAL launched to the ISS in May 2018, and has operated continuously since then as the world’s first multi-user quantum science facility in space. CAL is the first experimental facility to produce the fifth state of matter known as a Bose-Einstein condensate with ultracold rubidium atoms on orbit [1] and, more recently, with mixtures of rubidium and potassium [2]. We present an overview of CAL’s design and operation, review the scientific contributions to date, and discuss recent on-orbit upgrades to extend its useful mission lifetime and provide enhanced science. We also consider opportunities for follow-on missions informed by lessons learned from over five years of operation on orbit.

Optical clocks have well surpassed the frequency stability performance of microwave clocks. They have been mainly limited to tabletop setups and large rack-mount systems. Miniaturizing optical clocks will make the new technology and capability more ubiquitously applied to applications from navigation to fundamental science. Here we aim to develop a miniature space optical clock (mSOC) with the size of a compact microwave clock and capable of achieving a short-term stability of 10(-1)4 tau (-1/2) and noise floor of 10(-16). In this paper, we will describe the mSOC concept, discuss the experimental setup, and present recent results. We have demonstrated trapping single ions and characterized the ion lifetime in a 16-cc trap tube. The trap tube is completely sealed off without any active pump. We also constructed a clock laser referenced to a small ultra-low expansion reference cavity at a low 10(-14) level and observed the clock transition.

Quantum atomic sensors based on atom interferometry (AI) have recently led to the development of new techniques for the measurement of inertial forces, finding important applications in both fundamental physics and applied research. As these types of sensors have begun to mature, they have received increasing interest for deployment in the field and even in space. There has been significant effort in the past in reducing the size and complexity of the system for applications in size, weight, and power (SWaP) challenging environments such as space. Here, we report on a design and assembly of a low-SWaP all-semiconductor-based laser and optical system (LOS) suitable for operating an AI system for potential space applications. (c) 2024 Optica Publishing Group

A full-operated and turn-key clock laser is based on a compact Fabry Perot cavity is developed for the Yb ion clock. The cavity is disk shape with 2 inch diameter and 9.3 mm thickness. Though the compact size, the cavity features vibration insensitive design allowing vibration sensitivity on 10-10/g level. The cavity is installed in a two-layer thermal shield with 10 hours time constant which dramatically suppresses room temperature impact on the cavity. By optimizing the vibration and temperature induced noise, the frequency stability of the laser referenced to this cavity is measured at 2×10-14, mainly limited by the cavity thermal noise.

It is acknowledged that the sensitivity and accuracy achievable by atom-interferometric quantum sensors will have significantly impact many research areas. While the sensitivity of an atomic sensor scales quadratically to the interrogation time, making spaceborne quantum sensors particularly interesting, the measurement noise is limited by the quantum projection noise. The state of the art ultracold atom source for microgravity features 1E6 Rb atoms via Bose-Einstein Condensation (BEC). In this talk, we will present a feasibility study towards 1E8 Cs atoms below 1 nK for space applications. While Cs BEC is very challenging to generate, the choice of Cs versus Rb will be briefly discussed, in the scenario of quantum gravity gradiometer for mass change studies of Earth. Instead of BEC, direct laser cooling techniques are identified as an alternative and viable approach for high flux cold atom source. We will review laser cooling techniques and the identified path forward.

We have developed a prototype mercury ion clock in a miniature pumpless vacuum quadrupole trap tube employing a Spindt-type field-emitter array (FEA) as an electron source for ionization, an external 194-nm micro-plasma lamp for optical pumping, and a 40.5-GHz CMOS-based microwave synthesizer creating a clock capable of achieving the 10 −14 -stability level in one day. The physics package consists of the sealed 30cc vacuum tube with one layer of magnetic shielding, light source, and detector assembly. The complete system's SWaP (size, weight, and power) is 1.1 L, 1.2 kg, and < 6 W of power. System stability level is comparable to the widely used, much larger rack-mounted Microchip 5071A cesium frequency standard. Prototype clocks have operated for over 30 months.

Modern communication and navigation systems are increasingly relying on atomic clocks. As timing precision requirements increase, demands for lower SWaP (size, weight, and power) clocks rise. However, it has been challenging to break through the general trade‐off trend between the clock stability performance and SWaP. Here we demonstrate micro mercury trapped ion clock (M2TIC) prototypes integrated with novel micro‐fabricated technologies to simultaneously achieve high performance and low SWaP. The M2TIC prototypes could reach the 10‐stability level in 1 day with a SWaP of 1.1 L, 1.2 kg, and under 6 W of power. This stability level is comparable to the widely used rack‐mount Microchip 5071A cesium frequency standard. These standalone prototypes survived regular commercial shipping across the North American continent to a government laboratory, where their performance was independently tested. The M2TIC sets a new reference point for SWaP and performance and opens opportunities for high‐performance clocks in terrestrial and space applications.

Modern communication and navigation systems are increasingly relying on atomic clocks. As timing precision requirements increase, demands for lower SWaP (size, weight, and power) clocks rise. However, it has been challenging to break through the general trade-off trend between the clock stability performance and SWaP. Here we demonstrate micro mercury trapped ion clock (M2TIC) prototypes integrated with novel micro-fabricated technologies to simultaneously achieve high performance and low SWaP. The M2TIC prototypes could reach the 10^-14 -stability level in 1 day with a SWaP of 1.1 L, 1.2 kg, and under 6 W of power. This stability level is comparable to the widely used rack-mount Microchip 5071A cesium frequency standard. These standalone prototypes survived regular commercial shipping across the North American continent to a government laboratory, where their performance was independently tested. The M2TIC sets a new reference point for SWaP and performance and opens opportunities for high-performance clocks in terrestrial and space applications.

Modern communication and navigation systems are increasingly relying on atomic clocks. As timing precision requirements increase, demands for lower SWaP (size, weight, and power) clocks rise. However, it has been challenging to break through the general trade-off trend between the clock stability performance and SWaP. Here we demonstrate micro mercury trapped ion clock (M2TIC) prototypes integrated with novel micro-fabricated technologies to simultaneously achieve high performance and low SWaP. The M2TIC prototypes could reach the [Formula: see text]-stability level in 1 day with a SWaP of 1.1 L, 1.2 kg, and under 6 W of power. This stability level is comparable to the widely used rack-mount Microchip 5071A cesium frequency standard. These standalone prototypes survived regular commercial shipping across the North American continent to a government laboratory, where their performance was independently tested. The M2TIC sets a new reference point for SWaP and performance and opens opportunities for high-performance clocks in terrestrial and space applications.

Dark energy constitutes ~70% of the universe, which explains the observed accelerated expansion of the universe. While little is known about the nature of dark energy, it is conjectured that it is a new scalar field that interacts normal matter at the cosmological scale. Recently, cold atom experiments in laboratory have contributed significantly on the constraints of chameleon and symmetron parameters. These experiments are currently limited by the knowledge of the Newtonian gravity of the test masses, and eventually by the uncertainty of the gravitational constant G. In this talk, we will present a joint project between JPL and Leibniz University Hannover, in which atom interferometers will be implemented in the 4-second microgravity environment in the Einstein-Elevator facility at Hannover, Germany. We will illustrate the measurement concept for constraining dark energy models, and report the progress of the joint effort.