Polarization Recovery Research Articles

Study of consecutive eclipses of pulsar J0024-7204O

ABSTRACT The eclipses seen in the radio emission of some pulsars can be invaluable to study the properties of the material from the companion stripped away by the pulsar. We present a study of six consecutive eclipses of PSR J0024–7204O in the globular cluster 47 Tucanae as seen by the MeerKAT radio telescope in the UHF (544–1088 MHz) band. A high scintillation state boosted the signal during one of the orbits and allowed a detailed study of the eclipse properties. We measure significant dispersion measure (DM) variations and detect strong scattering that seems to be the dominating mechanism of the eclipses at these frequencies. A complete drop in the linear polarization together with a small increase in the rotation measure suggests the presence of a magnetic field of $\sim 2$ mG. The study of multiple eclipses allowed us to measure difference in the lengths of the eclipses and DM differences of $\sim 0.01$ pc cm$^{-3}$ in consecutive orbits. One orbit, in particular, shows a delay in recovery of the linear polarization and a visible delay in the arrival of the pulses caused by a stronger scattering event. We suggest that these are caused by a higher variance of density fluctuations during the event.

Training a Dataset Simulated Using RGB Images for an End-to-End Event-Based DoLP Recovery Network

Event cameras are bio-inspired neuromorphic sensors that have emerged in recent years, with advantages such as high temporal resolutions, high dynamic ranges, low latency, and low power consumption. Event cameras can be used to build event-based imaging polarimeters, overcoming the limited frame rates and low dynamic ranges of existing systems. Since events cannot provide absolute brightness intensity in different angles of polarization (AoPs), degree of linear polarization (DoLP) recovery in non-division-of-time (non-DoT) event-based imaging polarimeters is an ill-posed problem. Thus, we need a data-driven deep learning approach. Deep learning requires large amounts of data for training, and constructing a dataset for event-based non-DoT imaging polarimeters requires significant resources, scenarios, and time. We propose a method for generating datasets using simulated polarization distributions from existing red–green–blue images. Combined with event simulator V2E, the proposed method can easily construct large datasets for network training. We also propose an end-to-end event-based DoLP recovery network to solve the problem of DoLP recovery using event-based non-DoT imaging polarimeters. Finally, we construct a division-of-time event-based imaging polarimeter simulating an event-based four-channel non-DoT imaging polarimeter. Using real-world polarization events and DoLP ground truths, we demonstrate the effectiveness of the proposed simulation method and network.

Wake-Up and Imprint Effects in Hafnium Oxide-Based Ferroelectric Capacitors during Cycling with Different Interval Times

This work experimentally investigated the wake-up behaviors of hafnium oxide-based ferroelectric capacitors by manipulating the interval time between each characterization cycle. Both Positive-Up–Negative-Down (PUND) and Negative-Down–Positive-Up (NDPU) waveforms were used as the stress and measurement waveforms in the experiments. It was found that the imprint occurs as the total interval time increases to a several-seconds level. However, this only affects the remnant polarization (PR) of ferroelectric capacitors when stressed by NDPU waveforms, since the voltage amplitude saturates under the PUND stress conditions and does not influence the PR. The wake-up behavior has been proved to be caused by the defects redistribution during electrical cycling. Notably, when using PUND waveforms, the change in the interval time can result in different increase rates of PR, indicating the possibility of recovery during the intervals. This recovery leads to a slower wake-up when cycling with a longer interval time. Moreover, it is observed that this PR recovery could reach saturation after several seconds of the interval time. This comprehensive investigation of wake-up and imprint behaviors can provide new insights to evaluate and enhance the reliability of ferroelectric memories.

CLASS Angular Power Spectra and Map-component Analysis for 40 GHz Observations through 2022

Measurement of the largest angular scale (ℓ < 30) features of the cosmic microwave background (CMB) polarization is a powerful way to constrain the optical depth to reionization and search for the signature of inflation through the detection of primordial B-modes. We present an analysis of maps covering 73.6% of the sky made from the 40 GHz channel of the Cosmology Large Angular Scale Surveyor (CLASS) from 2016 August to 2022 May. Taking advantage of the measurement stability enabled by front-end polarization modulation and excellent conditions from the Atacama Desert, we show this channel achieves higher sensitivity than the analogous frequencies from satellite measurements in the range 10 < ℓ < 100. Simulations show the CLASS linear (circular) polarization maps have a white noise level of 125(130)μKarcmin . We measure the Galaxy-masked EE and BB spectra of diffuse synchrotron radiation and compare to space-based measurements at similar frequencies. In combination with external data, we expand measurements of the spatial variations of the synchrotron spectral energy density (SED) to include new sky regions and measure the diffuse SED in the harmonic domain. We place a new upper limit on a background of circular polarization in the range 5 < ℓ < 125 with the first bin showing D ℓ < 0.023 μKCMB2 at 95% confidence. These results establish a new standard for recovery of the largest-scale CMB polarization from the ground and signal exciting possibilities when the higher sensitivity and higher-frequency CLASS channels are included in the analysis.

Fingolimod improves diffuse brain injury by promoting AQP4 polarization and functional recovery of the glymphatic system.

Diffuse brain injury (DBI) models are characterized by intense global brain inflammation and edema, which characterize the most severe form of TBI. In a previous experiment, we found that fingolimod promoted recovery after controlled cortical impact injury (CCI) by modulating inflammation around brain lesions. However, it remains unclear whether fingolimod can also attenuate DBI because of its different injury mechanisms. Furthermore, whether fingolimod has additional underlying effects on repairing DBI is unknown. The impact acceleration model of DBI was established in adult Sprague-Dawley rats. Fingolimod (0.5 mg/kg) was administered 0.5, 24, and 48 h after injury for 3 consecutive days. Immunohistochemistry, immunofluorescence analysis, cytokine array, and western blotting were used to evaluate inflammatory cells, inflammatory factors, AQP4 polarization, apoptosis in brain cells, and the accumulation of APP after DBI in rats. To evaluate the function of the glymphatic system (GS), a fluorescent tracer was injected into the cistern. The neural function of rats with DBI was evaluated using various tests, including the modified neurological severity score (mNSS), horizontal ladder-crossing test, beam walking test, and tape sensing and removal test. Brain water content was also measured. Fingolimod administration for 3 consecutive days could reduce the levels of inflammatory cytokines, neutrophil recruitment, microglia, and astrocyte activation in the brain following DBI. Moreover, fingolimod reduced apoptotic protein expression, brain cell apoptosis, brain edema, and APP accumulation. Additionally, fingolimod inhibited the loss of AQP4 polarization, improved lymphatic system function, and reduced damage to nervous system function. Notably, inhibiting the GS weakened the therapeutic effect of fingolimod on the neurological function of rats with DBI and increased the accumulation of APP in the brain. In brief, these findings suggest that fingolimod alleviates whole-brain inflammation and GS system damage after DBI and that inhibiting the GS could weaken the positive effect of fingolimod on nerve function in rats with DBI. Thus, inhibiting inflammation and regulating the GS may be critical for the therapeutic effect of fingolimod on DBI.

Adalimumab combined with erythropoietin improves recovery from spinal cord injury by suppressing microglial M1 polarization-mediated neural inflammation and apoptosis.

Adalimumab (ADM), a humanized antibody against tumour necrosis factor (TNF), is widely applied in treating inflammatory and autoimmune diseases, but its usage in spinal cord injury (SCI) is rarely reported. Hence, this study aimed to explore the effect of ADM with or without erythropoietin (EPO) on microglial polarization, neuroinflammation, neural apoptosis, and functional recovery in SCI. Primary microglia were stimulated with lipopolysaccharide (LPS) and then treated with ADM, EPO, or ADM combined with EPO. Then, primary neurons were incubated in the microglial culture medium. SCI rats were established and then treated with ADM, EPO or ADM combined with EPO. ADM suppressed LPS-induced microglial M1 polarization, as reflected by downregulated iNOS and CD86 expression, and neuroinflammation, as reflected by decreased TNF-α, IL-1β, and IL-6 expression, in a dose-dependent manner. Moreover, ADM inhibited microglia-induced neural apoptosis, as reflected by TUNEL assay results and the expression of apoptotic markers (C-Caspase3 and Bcl2), in a dose-dependent manner. EPO monotherapy displayed an effect similar to that of ADM monotherapy. Furthermore, ADM combined with EPO therapy exhibited greater effects than either monotherapy in terms of inhibiting microglial M1 polarization, neuroinflammation, and neural apoptosis. In vivo experiments confirmed the findings of the in vitro experiments and showed that ADM combined with EPO improved SCI functional recovery and neural injury compared with monotherapy. ADM combined with EPO improves recovery from SCI by suppressing microglial M1 polarization-mediated neural inflammation and apoptosis.

Induced pluripotent stem cells as natural biofactories for exosomes carrying miR-199b-5p in the treatment of spinal cord injury.

Background: Induced pluripotent stem cells-derived exosomes (iPSCs-Exo) can effectively treat spinal cord injury (SCI) in mice. But the role of iPSCs-Exo in SCI mice and its molecular mechanisms remain unclear. This research intended to study the effects and molecular mechanism of iPSCs-Exo in SCI mice models. Methods: The feature of iPSCs-Exo was determined by transmission electron microscope (TEM), nanoparticle tracking analysis (NTA), and western blot. The effects of iPSCs-Exo in the SCI mice model were evaluated by Basso Mouse Scale (BMS) scores and H&E staining. The roles of iPSCs-Exo and miR-199b-5p in LPS-treated BMDM were verified by immunofluorescence, RT-qPCR, and Cytokine assays. The target genes of miR-199b-5p were identified, and the function of miR-199b-5p and its target genes on LPS-treated BMDM was explored by recuse experiment. Results: iPSCs-Exo improved motor function in SCI mice model in vivo, shifted the polarization from M1 macrophage to M2 phenotype, and regulated related inflammatory factors expression to accelerate the SCI recovery in LPS-treated BMDM in vitro. Meanwhile, miR-199b-5p was a functional player of iPSCs-Exo, which could target hepatocyte growth factor (Hgf). Moreover, miR-199b-5p overexpression polarized M1 macrophage into M2 phenotype and promoted neural regeneration in SCI. The rescue experiments confirmed that miR-199b-5p induced macrophage polarization and SCI recovery by regulating Hgf and Phosphoinositide 3-kinase (PI3K) signaling pathways. Conclusion: The miR-199b-5p-bearing iPSCs-Exo might become an effective method to treat SCI.

Optical Field Recovery in Jones Space

Optical full-field recovery allows for fiber impairments compensation such as chromatic dispersion and polarization mode dispersion (PMD) in the digital signal processing. For cost-sensitive short-reach optical networks, some advanced single-polarization (SP) optical field recovery schemes are recently proposed to avoid chromatic dispersion-induced power fading effect and improve the spectral efficiency for larger potential capacity. Polarization division multiplexing (PDM) can further double both the spectral efficiency and the system capacity of these SP carrier-assisted direct detection (DD) schemes. However, the so-called polarization fading phenomenon induced by random polarization rotation is a fundamental obstacle that prevents SP carrier-assisted DD systems from polarization diversity. In this paper, we propose a receiver of Jones-space field recovery (JSFR) to realize polarization diversity with SP carrier-assisted DD schemes. Different receiver structures and simplified recovery procedures for JSFR are explored theoretically. The proposed JSFR pushes SP DD schemes towards PDM without an extra optical signal-to-noise ratio (OSNR) penalty. In addition, the JSFR shows good tolerance to PMD since the optical field recovery is conducted before polarization recovery. In the concept-of-proof experiment, we demonstrate 448-Gb/s reception over 80-km single-mode fiber using the proposed JSFR based on 2 × 2 couplers. Furthermore, we qualitatively compare the optical field recovery in Jones space and Stokes space in terms of the modulation dimension and hardware complexity.

Insight into the negative magnetization and anomalous exchange-bias in DyFe5Al7 through neutron depolarization and neutron diffraction studies

We have provided the mesoscopic and microscopic understandings of polarity reversal of the magnetization or negative magnetization (NM) below T COMP = 93 K in an exotic magnetic material containing three magnetic sublattices, viz., DyFe5Al7 crystallizing in ThMn12 structure, using neutron depolarization and neutron diffraction techniques. A full recovery of the neutron beam polarization at the T COMP in a neutron depolarization experiment reveals a total compensation of magnetization inside the magnetic domains in the sample. The temperature-dependent neutron diffraction study under zero magnetic field has provided temperature dependencies of antiparallelly coupled Dy (M Dy(2a)) and Fe (M Fe(8f) and M Fe(8j)) sublattice magnetic moments along [100] direction. The dominance of |M Dy(2a)| over total Fe moment, , below T COMP leads to the NM in the compound. The magnetization versus magnetic field curves below the T COMP indicate the presence of field-induced spin reorientation in the compound. The magnetic field required for spin reorientation (H SR) is maximum at the lowest temperature and it decreases to zero as the temperature is increased to T COMP. Interestingly, the compound shows a finite exchange-bias (H EB) below the T COMP only, as evident from the field-cooled hysteresis loops, while at T > T COMP, H EB is almost zero. The cooling-field (H COOL) dependent study of H EB shows a slope change at H COOL ∼ H SR indicating a correlation of exchange-bias with spin-reorientation in the compound. This study, apart from revealing microscopic understanding of magnetic behavior of an exotic three magnetic sublattice system, provides a correlation among exchange-bias, magnetic compensation, and spin-reorientation phenomena.

Phase Noise Analysis of Resonator-Enhanced Electro-Optic Comb-Based Analog Coherent Receivers

We present an architecture for wavelength-division-multiplexed coherent data center links employing resonator-enhanced electro-optic frequency comb generators as both transmitter and local oscillator (LO) sources. We show that in each frequency comb, the phase noise in all comb lines is determined completely by the optical phase noise of the seed laser and the phase noise of the microwave oscillator. We propose an analog coherent receiver that performs carrier recovery on all wavelength channels using only two phase-locked loops. We use an independent cascade of phase shifters driven by marker tone detection in each channel for polarization recovery and compensation of a static optical phase shift. We study design examples for quadrature phase-shift keying and 16-ary quadrature amplitude modulation (16-QAM), determining requirements on the transmitter and LO seed laser linewidths and the LO frequency modulation (FM) response. We find that for a dual-polarization (DP) 16-QAM link with 17 wavelength channels, each operating at 56 GBaud, if the combined linewidth of the transmitter and LO seed lasers is 100 kHz, the LO seed laser requires an FM response that is flat from d.c. to several hundred MHz to maintain a phase-error penalty below 1 dB.

RNN-Based Demodulation Framework for Spectrum Narrowing in Ultra-Dense WDM Networks

To cope with the continuous traffic growth, spectral efficiency needs to be enhanced. Ultra-dense WDM systems, where narrower guard-bands are inserted between wavelength-division-multiplexed (WDM) signals than those used in conventional dense WDM (DWDM) systems, are expected to offer higher spectral efficiency. However, such systems are hindered by the spectrum narrowing induced by wavelength selective switches (WSSs) at nodes. As a result, intersymbol interference (ISI) can be excessive. Linear digital filters widely used in typical digital coherent receivers can equalize the ISI. However, ISI equalization yields noise enhancement due to the interaction between ISI and amplifier noise. Sequence estimation can alleviate the impact of this interaction; however, to introduce sequence estimation into real systems, an ISI-imposing filter is needed because the adaptive filter used for polarization recovery automatically equalizes the ISI. Although the optimum ISI-imposing filter can be created with the proper spectrum model, its characteristics change frequently in real optical path networks. Therefore, we need to develop a demodulation framework that does not necessitate any spectrum models. In this letter, we propose a novel demodulation framework that uses a recurrent neural network (RNN) to simultaneously realize the ISI-imposing filter and sequence estimator. Extensive computer simulations show that our proposal increases the transmission distance in ultra-dense WDM networks.

Urine Macrophages Polarization Predicts Renal Function Recovery after Nephron-Sparing Surgery in Patients with Renal Cell Carcinoma

Introduction: This study was conducted to investigate the underlying associations between urine macrophages polarization and renal function recovery after nephron-sparing surgery (NSS) in patients with renal cell carcinoma (RCC) and to explore the potential application values of urine macrophages polarization in predicting the severity of renal ischemia/reperfusion injury (RIRI). Methods: Sixty-two patients with unilateral RCC who underwent NSS in our departments were prospectively recorded and followed up for long-term renal function to assess the onset of acute kidney injury (AKI) and chronic kidney disease (CKD). Urine samples of patients were collected 72 h after surgery for analyzing pro-inflammatory (classically activated/M1) and pro-reparative (alternatively activated/M2) macrophages polarization by flow cytometry. The detailed correlations between urine macrophages polarization and renal function recovery after NSS were explored by statistical analyses. Results: The cumulative incidence of postoperative AKI was 27.4% (17/62), and 47.0% (8/17) of those eventually developed to CKD during the follow-up. The mean urine M1/M2 ratio was 10.54 ± 8.13 in the AKI group and 3.93 ± 3.10 in the non-AKI group, presenting a significant statistical difference (p < 0.0001). Meanwhile, the urine M1/M2 ratio presented amazing potential in predicting postoperative CKD as well, with a mean ratio of 12.54 ± 9.41 in the CKD group and 4.28 ± 3.21 in the non-CKD group (p < 0.0001). Though univariate analysis implied that urine M1/M2 ratio was a relevant factor of both postoperative AKI and CKD in NSS surgical patients, multivariate analysis did not show satisfying predicting potential in postoperative CKD, mainly due to the very limited candidates enrolled in this study. Conclusion: Urine macrophages polarization could predict renal function recovery after NSS in patients with RCC. The urine M1/M2 ratio might a potential biomarker of RIRI but needs to be further verified in clinical settings.

High Magnetic Field Affecting Dielectric Polarization and Partial Discharge Behavior of Epoxy Resin

In this article, a joint measurement of dielectric polarization, depolarization, and potential recovery is carried out to investigate the instantaneous and relaxation polarization characteristics of epoxy resin in high magnetic field. The dielectric polarization of epoxy resin is converted to a combination of weakened instantaneous polarization and the relaxation polarization with reduced amplitude and increased speed. Changes in dielectric polarization processes leads to the decrease of relative permittivity. Furthermore, partial discharge (PD) of internal defects is harder to be initiated in high magnetic field. However, the discharge frequency is increased and the phase distribution becomes wider in the case of ac. In the case of dc, discharge lasts for longer time in high magnetic field. The experimental results are caused by the coupling effects of high-speed polarization and abnormal charge accumulation at the gas-solid interface due to the effects of Lorentz force on charges generated by PD.

Temperature dependent partially compensated to nearly fully compensated magnetic state in half-metallic full Heusler alloy, Mn1.2Fe1.18V0.62Al

We report experimental and theoretical studies of magnetization compensation phenomenon in quaternary Heusler alloy Mn1.2Fe1.18V0.62Al by employing dc magnetization, neutron depolarization, neutron diffraction, specific heat, electrical resistivity, and electronic structure calculation. In this ferrimagnetic alloy system with ordering temperature TC = 360 K, the asymmetric thermal variations of the site magnetic moments provide an evidence of the partially compensated magnetic state of the system down to ∼ 48 K. However, below 48 K, the system exhibits its magnetic ground state with the negligibly small ordered moment of 0.05(5) μB/f.u. at 10 K, as obtained from the neutron diffraction study. Nearly full recovery of neutron beam polarization at 4 K in the neutron depolarization study also infers a nearly fully compensated magnetization state in this Heusler alloy. Temperature dependent specific heat and resistivity measurements also corroborate with the dc magnetization study representing 48 K as a turning point at which the system reaches its ground state. The electronic structure calculations, using the SPR-KKR Green’s function approach, verify the half-metallic nature of the present system. The net magnetic moment (0.06 μB/f.u.) obtained from the theoretical calculations as well as neutron diffraction experiments (0.05 μB/f.u.) is in good agreement with the Slater-Pauling rule (0.06 μB/f.u.). This small magnetic moment of the system (Mn0.82Fe1.18)(Mn0.38V0.62)Al proclaims to be a nearly compensated ferrimagnetic system with 23.94 valence electrons. Such magnetically compensated systems with finite spin polarization could be favorable for spintronics applications.

Prediction of Li-ion battery capacity degradation considering polarization recovery with a hybrid ensemble learning model

Polarization recovery is a phenomenon that significantly affects the capacity degradation behavior of lithium-ion battery (LIB). In this study, we demonstrated that capacity fluctuation during fading was highly correlated with polarization recovery through micro-Roman and rate performance tests. A series of aging experiments with a wide range of relaxation times (0.08 h to 200 h) were developed to analyze the effects of polarization recovery on discharge capacity. The experimental dataset includes 30,696 charge-discharge cycles under various conditions based on LiFePO4/graphite and LiNi0.8Co0.15Al0.05O2/graphite battery cells. Here, a hybrid ensemble learning model (HEL) was proposed to achieve accurate predictions while considering polarization recovery. Multiple highly correlated stress factors of polarization recovery were identified and then utilized as the input data of HEL. Our analysis shows that HEL is capable of precisely capturing capacity degradation with fluctuations due to polarization recovery, the implication of which is critical to the advancement of lifetime management in battery energy storage applications.

Extracellular vesicles from adipose-derived stem cells promote microglia M2 polarization and neurological recovery in a mouse model of transient middle cerebral artery occlusion

BackgroundAdipose-derived stem cells (ADSCs) and their extracellular vesicles (EVs) have therapeutic potential in ischemic brain injury, but the underlying mechanism is poorly understood. The current study aimed to explore the contribution of miRNAs in ADSC-EVs to the treatment of cerebral ischemia.MethodsAfter the intravenous injection of ADSC-EVs, therapeutic efficacy was evaluated by neurobehavioral tests and brain atrophy volume. The polarization of microglia was assessed by immunostaining and qPCR. We further performed miRNA sequencing of ADSC-EVs and analyzed the relationship between the upregulated miRNAs in ADSC-EVs and microglial polarization-related proteins using Ingenuity Pathway Analysis (IPA).ResultsThe results showed that ADSC-EVs reduced brain atrophy volume, improved neuromotor and cognitive functions after mouse ischemic stroke. The loss of oligodendrocytes was attenuated after ADSC-EVs injection. The number of blood vessels, as well as newly proliferated endothelial cells in the peri-ischemia area were higher in the ADSC-EVs treated group than that in the PBS group. In addition, ADSC-EVs regulated the polarization of microglia, resulting in increased repair-promoting M2 phenotype and decreased pro-inflammatory M1 phenotype. Finally, STAT1 and PTEN were highlighted as two downstream targets of up-regulated miRNAs in ADSC-EVs among 85 microglia/macrophage polarization related proteins by IPA. The inhibition of STAT1 and PTEN by ADSC-EVs were confirmed in cultured microglia.ConclusionsIn summary, ADSC-EVs reduced ischemic brain injury, which was associated with the regulation of microglial polarization. miRNAs in ADSC-EVs partly contributed to their function in regulating microglial polarization by targeting PTEN and STAT1.

Phoenixin-14 Promotes the Recovery of Neurological Dysfunction After Spinal Cord Injury by Regulating Microglial Polarization via PTEN/Akt Signaling Pathway.

Spinal cord injury (SCI) is a destructive event in central nervous system (CNS) with the hallmark of deficits in neuronal function. Phoenixin-14 (PNX-14) is a reproductive peptide that also has neuroprotective effects. However, the role of PNX-14 in SCI has not yet been studied. In this study, we firstly investigated the effects of PNX-14 on the recovery of neurological dysfunction and microglial polarization in a SCI mice model. We demonstrated that PNX-14 improved the recovery of neurological dysfunction with increased Basso Mouse Scale (BMS) scores, reduced lesion area volume and Evans blue (EB) dye extravasation. PNX-14 alleviated neuronal apoptosis and neuroinflammation in mice underwent SCI. In vitro co-culture assay proved that PNX-14 protected neurons injury in response to LPS- activated BV-2 cells. PNX-14 suppressed the LPS- induced microglia M1 phenotype polarization with decreased expression of M1-associated markers (CD16 and iNOS) and increased expression of M2-associated markers (CD206 and Arg1). PNX-14 also suppressed LPS- caused decrease in anti-inflammatory cytokines TGF-β, IL-10, and IL-13, as well increase in pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 in BV2 cells. PNX-14 treatment caused increased PTEN expression and decreased p-Akt expression in BV2 cells against LPS induction. While inhibition of PTEN by SF1670 reversed the effects of PNX-14 on LPS- induced phenotypic transition of BV2 cells. Taken together, we found that PNX-14 exerted protective effects on neurological dysfunction and inflammation in SCI mice through modulating microglial polarization via PTEN/Akt signaling pathway.

Analysis of Political Polarization and Economic Recovery in Coronavirus Policy

Analysis of Political Polarization and Economic Recovery in Coronavirus Policy

Almost complete revivals in quantum many-body systems

Revivals of initial non-equilibrium states is an ever-present concern for the theory of dynamic thermalization in many-body quantum systems. Here we consider a nonintegrable lattice of interacting spins 1/2 and show how to construct a quantum state such that a given spin 1/2 is maximally polarized initially and then exhibits an almost complete recovery of the initial polarization at a predetermined moment of time. An experimental observation of such revivals may be utilized to benchmark quantum simulators with a measurement of only one local observable. We further propose to utilize these revivals for a delayed disclosure of a secret.

Toward Optimal Signal Extraction for Imaging X-Ray Polarimetry

Abstract We describe an optimal signal extraction process for imaging X-ray polarimetry using an ensemble of deep neural networks. The initial photoelectron angle, used to recover the polarization, has errors following a von Mises distribution. This is complicated by events converting outside of the fiducial gas volume, whose tracks have little polarization sensitivity. We train a deep ensemble of convolutional neural networks to select against these events and to measure event angles and errors for the desired gas-conversion tracks. We show how the expected modulation amplitude from each event gives an optimal weighting to maximize signal-to-noise ratio of the recovered polarization. Applying this weighted maximum likelihood event analysis yields sensitivity (MDP99) improvements of ∼10% over earlier heuristic weighting schemes and mitigates the need to adjust said weighting for the source spectrum. We apply our new technique to a selection of astrophysical spectra, including complex extreme examples, and compare the polarization recovery to the current state of the art.