Quantum Sensing Technologies and Smart Cities:Opportunities and Challenges

Quantum technologies are likely to raise significant benefits but also challenges to the continued development of smart cities. This paper looks at one of the more operationally ready of the quantum technologies, namely quantum sensing, and considers some of the opportunities and challenges facing city planners if they wish to introduce the capabilities of quantum sensing. The paper briefly outlines the evolution of quantum technologies and where quantum sensing fits in the quantum portfolio. It then considers two quantum sensing capabilities in more detail, namely the use of quantum sensing in navigation and in detection. The paper then describes the attributes of smart cities and discusses the opportunities and challenges of the introduction of these two quantum sensing capabilities, and outlines potential mitigation strategies to optimize the benefits while addressing the challenges

Drivers of persistent changes in the global methane cycle under aggressive mitigation action

To achieve the Paris climate agreement goals, methane (CH4) emission mitigation plays a key role. Therefore, a better understanding of the global methane cycle is indispensable. Here we simulate the global methane cycle fully interactively from 1850 to 2100 with a strong mitigation action scenario (SSP1-2.6) post 2014. We show that the atmospheric methane burden largely recovers to early 20th-century levels, while wetland methane emissions follow a persistent upward trend from 166 Tg(CH4) yr–1 at pre-industrial to 221 Tg(CH4) yr–1 in 2100. The methane lifetime decreases from 9.3 to 7.3 years over the 1850–2100 period. We identify net primary productivity as the main driver behind the wetland methane trend with R2 = 0.7. This implies that important components of the methane cycle (wetland methane, methane lifetime) are subject to Earth system feedbacks, potentially impacting any prospective methane mitigation action. Therefore, methane mitigation strategies will need to consider feedbacks in the Earth system

Eclipse Mapping with MIRI:2D Map of HD 189733b from 8 μ m JWST MIRI LRS Observations

Observations and models of transiting hot Jupiter exoplanets indicate that atmospheric circulation features may cause large spatial flux contrasts across their daysides. Previous studies have mapped these spatial flux variations through inversion of secondary eclipse data. Though eclipse mapping requires high signal-to-noise data, the first successful eclipse map—made for HD 189733b using 8 μm Spitzer IRAC data—showed the promise of the method. JWST eclipse observations provide the requisite data quality to access the unique advantages of eclipse mapping. Using two JWST MIRI low-resolution spectroscopy eclipse observations centered on 8 μm to mimic the Spitzer bandpass used in previous studies, combined with the Spitzer IRAC 8 μm eclipses and partial phase curve (necessitated to disentangle map and systematic signals), we present a two-dimensional dayside temperature map. Our best-fit model is a two-component fifth-degree harmonic model with an unprecedentedly constrained eastward hotspot offset of 33.0−0.9+0.7 deg. We rule out a strong hemispheric latitudinal hotspot offset, as three + component maps providing latitudinal degrees of freedom are strongly disfavored. As in previous studies, we find some model dependence in longitudinal hotspot offset; when we explore and combine a range of proximal models to avoid an overly constrained confidence region, we find an eastward hotspot offset of 32.5−10.6+3.0 deg, indicating the presence of a strong eastward zonal jet. Our map is consistent with some previous eclipse maps of HD 189733b, though it indicates a higher longitudinal offset from others. It is largely consistent with predictions from general circulation models at the 115 mbar level near the 8 μm photosphere

zkMixer:A Configurable Zero-Knowledge Mixer with Anti-Money Laundering Consensus Protocols

We introduce a zero-knowledge cryptocurrency mixer framework that allows groups of users to set up a mixing pool with configurable governance conditions, configurable deposit delays, and the ability to refund or confiscate deposits if it is suspected that funds originate from crime. Using a consensus process, group participants can monitor inputs to the mixer and determine whether the inputs satisfy the mixer conditions. If a deposit is accepted by the group, it will enter the mixer and become untraceable. If it is not accepted, the verifiers can freeze the deposit and collectively vote to either refund the deposit back to the user, or confiscate the deposit and send it to a different user. This behaviour can be used to examine deposits, determine if they originate from a legitimate source, and if not, return deposits to victims of crime

Generating auxeticity in graphene Kirigami with rectangular and rhomboidal perforations

Graphene Kirigami presents a transformative approach to achieving tunable auxeticity in two-dimensional materials. This study employs molecular dynamics simulations to explore the mechanical behavior of graphene with rectangular and rhomboidal perforations. The findings reveal that auxeticity, characterized by a negative Poisson's ratio (NPR), can be precisely controlled by manipulating geometric parameters such as aspect ratio (AR) and intercell spacing (IS). Structures with larger AR and smaller IS exhibit enhanced auxetic behavior, with rectangular perforations outperforming rhomboidal ones. Mechanistically, the interplay between in-plane rotation and out-of-plane deformation of Kirigami units drives the NPR, bridging macroscopic design concepts with nanoscale material phenomena. These results provide critical insights for designing graphene-based nanoscale devices with tunable mechanical properties, enabling advancements in flexible electronics, sensors, and actuators

Truly Supercritical Trade-Offs for Resolution, Cutting Planes, Monotone Circuits, and Weisfeiler–Leman

We exhibit supercritical trade-off for monotone circuits, showing that there are functions computable by small circuits for which any circuit must have depth super-linear or even super-polynomial in the number of variables, far exceeding the linear worst-case upper bound. We obtain similar trade-offs in proof complexity, where we establish the first size-depth trade-offs for cutting planes and resolution that are truly supercritical, i.e., in terms of formula size rather than number of variables, and we also show supercritical trade-offs between width and size for treelike resolution. Our results build on a new supercritical width-depth trade-off for resolution, obtained by refining and strengthening the compression scheme for the Cop-Robber game in [Grohe, Lichter, Neuen & Schweitzer 2023]. This yields robust supercritical trade-offs for dimension versus iteration number in the Weisfeiler-Leman algorithm, which also translate into trade-offs between number of variables and quantifier depth in first-order logic. Our other results follow from improved lifting theorems that might be of independent interest

Rapid Experimental Characterisation of A.C. Losses in Printed Litz Hairpins

In electric machines, higher operating fundamental frequencies result in more significant AC winding losses, further increased by inverter-induced loss at high switching frequencies. Winding AC loss characteristics may be improved with novel geometries made possible by advancements in additive manufacturing techniques, such as including targeted Litz stranding within the active length of hairpin bars. A challenge with additive manufacture is the variability in surface finish, strand separation tolerances, and electrical conductivity which impact the subsequent performance of the hairpins. This paper introduces a rapid characterisation test bench and analysis tool for validating the success of manufacturing and post-processing of additive manufactured hairpin samples. A motorette fixture is made to replicate the application slot geometry using a ferrite core to minimise parasitic iron loss. Two approaches are adopted for rapid measurement of the AC loss in the winding sample: 1. Measurement of air gap flux using a search coil in the slot with the test sample (Poynting Vector); 2. Impedance measurement of the change in primary coil resistance. The results, analysis, and accuracy of these methods are compared. Results are presented for additively manufactured Litz hairpin samples of different geometries at varying fundamental frequency