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1. Bounding the Minimum Time of a Quantum Measurement

   https://doi.org/10.22331/q-2023-11-14-1182  

   Shettell, Nathan; Centrone, Federico; García-Pintos, Luis Pedro (November 2023, Quantum)

   Measurements take a singular role in quantum theory. While they are often idealized as an instantaneous process, this is in conflict with all other physical processes in nature. In this Letter, we adopt a standpoint where the interaction with an environment is a crucial ingredient for the occurrence of a measurement. Within this framework, we derive lower bounds on the time needed for a measurement to occur. Our bound scales proportionally to the change in entropy of the measured system, and decreases as the number of of possible measurement outcomes or the interaction strength driving the measurement increases. We evaluate our bound in two examples where the environment is modelled by bosonic modes and the measurement apparatus is modelled by spins or bosons. 

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2. Enhancing Vehicle Flow in Random Environments through Dynamic Allocation of Sensing Resources

   S. Kassir and G. de Veciana (September 2022, IEEE Vehicular Technology Conference (VTC))

   This paper presents a theoretical analysis for a self-driving vehicle’s velocity as it navigates through a random environment. We study a stylized environment and vehicle mobility model capturing the essential features of a self-driving vehicle’s behavior, and leverage results from stochastic geometry to characterize the distribution of a typical vehicle’s safe driving velocity, as a function of key network parameters such as the density of objects in the environment and sensing accuracy. We then consider a setting wherein the sensing accuracy is subject to a sensing/communication rate constraint. We propose a procedure that focuses the vehicle’s sensing/communication resources and estimation efforts on the objects that affect its velocity and safety the most so as to optimize its ability to drive faster in uncertain environments. Simulation results show that the proposed methodology achieves considerable gains in the vehicle’s safe driving velocity as compared to uniform rate allocation policies. 

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3. Correlation-driven attosecond photoemission delay in the plasmonic excitation of C ₆₀ fullerene

   https://doi.org/10.1126/sciadv.ads0494  

   Biswas, Shubhadeep; Trabattoni, Andrea; Rupp, Philipp; Magrakvelidze, Maia; Madjet, Mohamed El-Amine; De_Giovannini, Umberto; Castrovilli, Mattea C; Galli, Mara; Liu, Qingcao; Månsson, Erik P; et al (February 2025, Science Advances)

   Extreme light confinement in plasmonic nanosystems enables novel applications in photonics, sensor technology, energy harvesting, biology, and quantum information processing. Fullerenes represent an extreme case for nanoplasmonics: They are subnanometer carbon-based molecules showing high-energy and ultrabroad plasmon resonances; however, the fundamental mechanisms driving the plasmonic response and the corresponding collective electron dynamics are still elusive. Here, we uncover the dominant role of electron correlations in the dynamics of the giant plasmon resonance (GPR) of the subnanometer system C₆₀by using attosecond photoemission chronoscopy. We find a characteristic photoemission delay of up to about 300 attoseconds that is purely induced by coherent large-scale electron correlations in the plasmonic potential. These results provide insights into the nature of the plasmon resonances in subnanometer systems and open perspectives for advancing nanoplasmonic applications. 

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4. Autonomous Urban Localization and Navigation with Limited Information

   https://doi.org/10.1109/IVS.2018.8500693  

   Chipka, Jordan B.; Campbell, Mark (June 2018, 2018 IEEE Intelligent Vehicles Symposium (IV))

   Urban environments offer a challenging scenario for autonomous driving. Globally localizing information, such as a GPS signal, can be unreliable due to signal shadowing and multipath errors. Detailed a priori maps of the environment with sufficient information for autonomous navigation typically require driving the area multiple times to collect large amounts of data, substantial post-processing on that data to obtain the map, and then maintaining updates on the map as the environment changes. This paper addresses the issue of autonomous driving in an urban environment by investigating algorithms and an architecture to enable fully functional autonomous driving with limited information. An algorithm to autonomously navigate urban roadways with little to no reliance on an a priori map or GPS is developed. Localization is performed with an extended Kalman filter with odometry, compass, and sparse landmark measure ment updates. Navigation is accomplished by a compass-based navigation control law. Key results from Monte Carlo studies show success rates of urban navigation under different environmental conditions. Experiments validate the simulated results and demonstrate that, for given test conditions, an expected range can be found for a given success rate. 

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5. Long-lived quantum coherent dynamics of a Λ-system driven by a thermal environment

   https://doi.org/10.1063/5.0102808  

   Koyu, Suyesh; Tscherbul, Timur V. (September 2022, The Journal of Chemical Physics)

   We present a theoretical study of quantum coherent dynamics of a three-level Λ-system driven by a thermal environment (such as blackbody radiation), which serves as an essential building block of photosynthetic light-harvesting models and quantum heat engines. By solving nonsecular Bloch–Redfield master equations, we obtain analytical results for the ground-state population and coherence dynamics and classify the dynamical regimes of the incoherently driven Λ-system as underdamped and overdamped depending on whether the ratio Δ/[ rf( p)] is greater or less than one, where Δ is the ground-state energy splitting, r is the incoherent pumping rate, and f( p) is a function of the transition dipole alignment parameter p. In the underdamped regime, we observe long-lived coherent dynamics that lasts for τ c ≃ 1/ r, even though the initial state of the Λ-system contains no coherences in the energy basis. In the overdamped regime for p = 1, we observe the emergence of coherent quasi-steady states with the lifetime τ c = 1.34( r/Δ 2 ), which have a low von Neumann entropy compared to conventional thermal states. We propose an experimental scenario for observing noise-induced coherent dynamics in metastable He* atoms driven by x-polarized incoherent light. Our results suggest that thermal excitations can generate experimentally observable long-lived quantum coherent dynamics in the ground-state subspace of atomic and molecular Λ-systems in the absence of coherent driving. 

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