arXiv subjects

Lin Jin

Publications and source records attributed to Lin Jin.

7 recordsLinked to original sources

arXiv2026

Geometry-enabled magnetic resilience in superconducting nanowire single-photon detectors

While magnetic fields and superconductors are both central to classical and quantum technologies, their combined use is often challenging, as magnetic fields significantly affect superconducting device performance. In superconducting nanowire single-photon detectors (SNSPDs), magnetic fields drastically reduce detection efficiencies, hampering their application in magnetically-active classical and quantum photonics. Here, we systematically characterize the performance of NbTiN SNSPDs under magnetic fields and show the enhancement of their intrinsic detection efficiency (IDE) at lower bias currents and its suppression at higher currents. This leads to SNSPD performance degradation through reduced or disappearing saturation plateaus. We show that the magnitude of this degradation is highly dependent on nanowire width and demonstrate width-optimized SNSPDs with saturating IDE for a wide range of photon energies under application-relevant magnetic fields. Minimizing degradation in superconducting devices under magnetic fields enables applications like detector-integrated spin-optic and atomic quantum processors, high-sensitivity magnetometry, and quantum transduction.

cond-mat.supr-con↗

arXiv2025

On Sampling of Multiple Correlated Stochastic Signals

Multiple stochastic signals possess inherent statistical correlations, yet conventional sampling methods that process each channel independently result in data redundancy. To leverage this correlation for efficient sampling, we model correlated channels as a linear combination of a smaller set of uncorrelated, wide-sense stationary latent sources. We establish a theoretical lower bound on the total sampling density for zero mean-square error reconstruction, proving it equals the ratio of the joint spectral bandwidth of latent sources to the number of correlated signal channels. We then develop a constructive multi-band sampling scheme that attains this bound. The proposed method operates via spectral partitioning of the latent sources, followed by spatio-temporal sampling and interpolation. Experiments on synthetic and real datasets confirm that our scheme achieves near-lossless reconstruction precisely at the theoretical sampling density, validating its efficiency.

eess.SP↗

arXiv2024

Enhanced control of single-molecule emission frequency and spectral diffusion

The Stark effect provides a powerful method to shift the spectra of molecules, atoms and electronic transitions in general, becoming one of the simplest and most straightforward way to tune the frequency of quantum emitters by means of a static electric field. At the same time, in order to reduce the emitter sensitivity to charge noise, inversion symmetric systems are typically designed, providing a stable emission frequency, with a quadratic-only dependence on the applied field. However, such nonlinear behaviour might reflect in correlations between the tuning ability and unwanted spectral fluctuations. Here, we provide experimental evidence of this trend, using molecular quantum emitters in the solid state cooled down to liquid helium temperatures. We finally combine the electric field generated by electrodes, which results parallel to the molecule induced dipole, to optically excite long-lived charge states, acting in the perpendicular direction. Based on the anisotropy of the molecule's polarizability, our two-dimensional control of the local electric field allows not only to tune the emitter's frequency but also to sensibly suppress the spectral instabilities associated to field fluctuations.

quant-ph↗

arXiv2024

Pathfinder: Exploring Path Diversity for Assessing Internet Censorship Inconsistency

Internet censorship is typically enforced by authorities to achieve information control for a certain group of Internet users. So far existing censorship studies have primarily focused on country-level characterization because (1) in many cases, censorship is enabled by governments with nationwide policies and (2) it is usually hard to control how the probing packets are routed to trigger censorship in different networks inside a country. However, the deployment and implementation of censorship could be highly diverse at the ISP level. In this paper, we investigate Internet censorship from a different perspective by scrutinizing the diverse censorship deployment inside a country. Specifically, by leveraging an end-to-end measurement framework, we deploy multiple geo-distributed back-end control servers to explore various paths from one single vantage point. The generated traffic with the same domain but different control servers' IPs could be forced to traverse different transit networks, thereby being examined by different censorship devices if present. Through our large-scale experiments and in-depth investigation, we reveal that the diversity of Internet censorship caused by different routing paths inside a country is prevalent, implying that (1) the implementations of centralized censorship are commonly incomplete or flawed and (2) decentralized censorship is also common. Moreover, we identify that different hosting platforms also result in inconsistent censorship activities due to different peering relationships with the ISPs in a country. Finally, we present extensive case studies in detail to illustrate the configurations that lead to censorship inconsistency and explore the causes.

cs.CR↗

arXiv2021

Integrative Wireless Device for Remote Continuous Blood Biomarker Monitoring

To perform precision medicine in realtime at home, a device capable of long distance continuously monitoring target biomolecules in unprocessed blood under dynamic situations is essential. In this study, an integrative buffer free wireless device is developed to measure drug concentrations in patients blood in real time for remote clinical healthcare. To demonstrate its capability, the drug molecules (i.e., small molecule drug doxorubicin, DOX) are continuously measured in the unprocessed whole blood of live animals (e.g., rats). The dynamic changes of drug concentrations with sub minute temporal resolution are recorded for an extended period of time (8 hours). As an advance in remote diagnosis, this device would benefit the public by enabling long-distance precision medicine to prevent pandemics in advance.

physics.med-ph↗

arXiv2020

Coherent characterisation of a single molecule in a photonic black box

Extinction spectroscopy is a powerful tool for demonstrating the coupling of a single quantum emitter to a photonic structure. However, it can be challenging in all but the simplest of geometries to deduce an accurate value of the coupling efficiency from the measured spectrum. Here we develop a theoretical framework to deduce the coupling efficiency from the measured transmission and reflection spectra without precise knowledge of the photonic environment. We then consider the case of a waveguide interrupted by a transverse cut in which an emitter is placed. We apply that theory to a silicon nitride waveguide interrupted by a gap filled with anthracene that is doped with dibenzoterrylene molecules. We describe the fabrication of these devices, and experimentally characterise the waveguide coupling of a single molecule in the gap.

quant-ph↗

arXiv2014

Bayesian Multi-Scale Optimistic Optimization

Bayesian optimization is a powerful global optimization technique for expensive black-box functions. One of its shortcomings is that it requires auxiliary optimization of an acquisition function at each iteration. This auxiliary optimization can be costly and very hard to carry out in practice. Moreover, it creates serious theoretical concerns, as most of the convergence results assume that the exact optimum of the acquisition function can be found. In this paper, we introduce a new technique for efficient global optimization that combines Gaussian process confidence bounds and treed simultaneous optimistic optimization to eliminate the need for auxiliary optimization of acquisition functions. The experiments with global optimization benchmarks and a novel application to automatic information extraction demonstrate that the resulting technique is more efficient than the two approaches from which it draws inspiration. Unlike most theoretical analyses of Bayesian optimization with Gaussian processes, our finite-time convergence rate proofs do not require exact optimization of an acquisition function. That is, our approach eliminates the unsatisfactory assumption that a difficult, potentially NP-hard, problem has to be solved in order to obtain vanishing regret rates.

stat.ML↗