Single-Photon Detection by a Dirty Current-Carrying Superconducting Strip Based on the Kinetic-Equation Approach
By D. Vodolazov. 2016
135 citations recorded by the source corpus.
Using kinetic equation approach we study dynamics of electrons and phonons in current-carrying superconducting nanostrips after absorption of single photon of near-infrared or optical range. We find that the larger the ratio $C_e/C_{ph}|_{T_c}$ ($T_c$ is a critical temperature of superconductor, $C_e$ and $C_{ph}$ are specific heat capacities of electrons and phonons, respectively) the larger part of photon's energy goes to electrons, they become stronger heated and, hence, could thermalize faster during initial stage of hot spot formation. Thermalization time $\tau_{th}$ could be less than one picoseconds for superconductors with $C_e/C_{ph}|_{T_c}\gg 1$ and small diffusion coefficient $D\simeq 0.5 cm^2/s$ when thermalization occurs mainly due to electron-phonon and phonon-electron scattering in relatively small volume $\sim \xi^2d$ ($\xi$ is a superconducting coherence length, $d<\xi$ is a thickness of the strip). At larger times due to diffusion of hot electrons effective temperature inside the hot spot decreases, the size of hot spot increases, superconducting state becomes unstable and normal domain spreads in the strip at current larger than so-called detection current. We find dependence of detection current on the photon's energy, place of its absorption in the strip, width of the strip, magnetic field and compare it with existing experiments. Our results demonstrate that materials with $C_e/C_{ph}|_{T_c} \ll 1$ are bad candidates for single photon detectors due to small transfer of photon's energy to electronic system and large $\tau_{th}$. We also predict that even several microns wide dirty superconducting bridge is able to detect single near-infrared or optical photon if its critical current exceeds 70 $\%$ of depairing current and $C_e/C_{ph}|_{T_c} \gtrsim 1$.
Subfields: Artificial Intelligence, Biomedical Engineering, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/5f86dab6e21e35b925f796cb7b1c6bb0afbfb792
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Citations in the corpus
- Superconducting nanowire single-photon detectors for quantum information (2020, methodology): “Vodolazov recently discussed the detection mechanism of an SNSPD based on the kinetic equation approach [68].”
- Waveguide-integrated superconducting nanowire single-photon detectors (2018, background): “The working mechanism of SNSPDs is based on the suppression of the superconducting state upon the absorption of a photon, which is transduced into a detectable electrical signal [17, 18].”