arXiv subjects

F. B. Baalbergen

Publications and source records attributed to F. B. Baalbergen.

4 recordsLinked to original sources

arXiv2026

Extracting Photon-Number Information from Superconducting Nanowire Single-Photon Detectors Traces via Mean-Derivative Projection

Photon-number resolved detection with superconducting nanowire single-photon detectors (SNSPDs) attracts increasing interest, but lacks a systematic framework for interpreting and benchmarking this capability. In this work, we combine principal component analysis (PCA) with a new readout technique to explore the photon-number resolving capabilities of SNSPDs and find that the information of the photon number is contained in a single principal component which approximates the time derivative of the average response trace. We introduce a new confidence metric based on the Bhattacharyya coefficient to quantify the photon-number-resolving capabilities of a detector system and show that this metric can be used to compare different systems. Our analysis and interpretation of the principal components imply that photon-number resolution in SNSPDs can be achieved with moderate hardware requirements in terms of both sample rate (5 GSample/sec) and analog bandwidth (3 GHz) and could be implemented in an FPGA, giving a highly scalable solution for real-time photon counting.

quant-ph↗

arXiv2025

Laser-Induced Relaxation Oscillations in Superconducting Nanobridge Single Photon Detectors

We demonstrate novel laser-induced relaxation oscillations in superconducting nanowire single photon detectors (SNSPDs). These oscillations appear when a voltage biased NbTiN nanobridge detector is illuminated with intense pulsed laser light at a repetition rate of $\sim19\text{MHz}$. They differ from the well-known relaxation oscillations by a step-wise increase in frequency and phase locking of the oscillations to the laser pulses. We create a model that incorporates electrical feedback and excludes thermal effects to simulate and explain the origin of the observed laser-induced relaxation oscillations. Qualitative agreement to the experiment is achieved using realistic values for the parameters in the model.

cond-mat.supr-con↗

arXiv2025

Markov chain Monte Carlo Detector Tomography applied to a NbTiN nanobridge

We demonstrate the use of a flexible and highly accurate Markov chain Monte Carlo Quantum Detector Tomography method as a minimization algorithm to best describe the response of an efficient $120 nm$ wide NbTiN superconducting nanobridge single photon detector. Separation of the internal quantum efficiency and external quantum efficiency is possible due to the difference in saturation behavior of an ideal 1-photon threshold detector as compared to a detector with non-unity 1-photon internal quantum efficiency. From a statistical analysis of our measurements (at $T=4.23\pm0.01K$, $I=29.4\pm0.1μA$, $I/I_\text{switch}=0.90\pm0.01$) we find an external quantum efficiency $η=(1.60\pm0.05)\cdot10^{-6}$, a 1-photon internal quantum efficiency $p_1=0.568\pm0.008$ and unity multi-photon (2 or more) internal quantum efficiency.

quant-ph↗

arXiv2022

Observation of microcavity fine structure

We observe fine structure in the resonance spectra of optical microcavities. We identify the polarization-resolved modes in the spectrum and find that resonance frequencies split in accordance with the theoretical prediction. The observed fine structure is dominantly caused by an optical spin-orbit coupling and non-paraxial propagation and reflection. Both effects are intrinsic, i.e. present in an ideal rotation-symmetric system, and scale inversely proportional to the mirror radius of curvature. For cavities with a small radius of curvature, the influence of fine structure on the resonance spectrum is important and unavoidable and should thus be taken into account.

physics.optics↗