arXiv subjects

Andrey Danilov

Publications and source records attributed to Andrey Danilov.

5 recordsLinked to original sources

arXiv2025

Quantum-Ready Microwave Detection with Scalable Graphene Bolometers in the Strong Localization Regime

Exploiting quantum interference of charge carriers, epitaxial graphene grown on silicon carbide emerges as a game-changing platform for ultra-sensitive bolometric sensing, featuring an intrinsic resistive thermometer response unmatched by any other graphene variant. By achieving low and uniform carrier densities, we have accessed a new regime of strong charge localization that dramatically reduces thermal conductance, significantly enhancing bolometer performance. Here we present scalable graphene-based bolometers engineered for detecting GHz-range photons, a frequency domain essential for superconducting quantum processors. Our devices deliver a state-of-the-art noise equivalent power of 40 zW$/\sqrt{\rm Hz}$ at $T=40~$mK, enabled by the steep temperature dependence of thermal conductance, $G_{\rm th}\sim T^4$ for $T<100~$mK. These results establish epitaxial graphene bolometers as versatile and low-back-action detectors, unlocking new possibilities for next-generation quantum processors and pioneering investigations into the thermodynamics and thermalization pathways of strongly entangled quantum systems.

cond-mat.mes-hall↗

arXiv2024

Study of $^{7}$Li+$^{10}$B elastic scattering and the lithium-induced reaction of one-nucleon transfers from $^{10}$B($^{7}$Li,$^{6}$Li)$^{11}$B

The angular distributions of elastic scattering of $^{7}$Li, as well as the lithium-induced reaction of one-nucleon transfers $^{10}$B($^{7}$Li,$^{6}$Li)$^{11}$B were measured at $E_\text{lab}$ = 58 MeV. Experiment was done using U-400 accelerator beam of the FLNR JINR, Dubna. Angular distribution for reaction $^{10}$B($^{7}$Li,$^{6}$Li)$^{11}$B with excitation of the 3.56 MeV state ($^{6}$Li*) is presented for the first time. The DWBA analysis of the differential cross section of the $^{10}$B($^{7}$Li,$^{6}$Li)$^{11}$B ground state (g.s.) transition and excited ($J^π$ = 0$^+$, $T$ = 1, $E$ = 3.56 MeV) state of $^{6}$Li transition was performed. The optical model potentials were obtained by fitting of measured elastic scattering data and evaluating parameters for the output reaction channels. Phenomenological approach based on solving an approximate equation for the reaction form factor was used to determine its radial dependence and empirical values of asymptotic normalization coefficient (ANC). Obtained values of ANCs for the $^{6}$Li$_\text{g.s.}$ and $^{6}$Li*(3.56 MeV) states are in agreement with the literature ones. Comparison of the radial dependences of form factors shows that the wave function of the $^{6}$Li nucleus in excited ($J^π$ = 0$^+$, $T$ = 1, $E$ = 3.56 MeV) state has increased spatial dimension compared to the ground state. This result is an argument in favor of a halo existence in $^{6}$Li*(3.56 MeV) state, while the question of a halo in $^{6}$Li$_\text{g.s.}$ still leaves open.

nucl-ex↗

arXiv2023

Scaling of self-stimulated spin echoes

Self-stimulated echoes have recently been reported in the high cooperativity and inhomogeneous coupling regime of spin ensembles with superconducting resonators. In this work, we study their relative amplitudes using echo-silencing made possible by a fast frequency tunable resonator. The highly anisotropic spin linewidth of Er$^{3+}$ electron spins in the CaWO$_4$ crystal also allows to study the dependence on spin-resonator ensemble cooperativity. It is demonstrated that self-stimulated echoes primarily result from a combination of two large control pulses and the echo preceding it.

quant-ph↗

arXiv2020

Pulsed Electron Spin Resonance of an Organic Microcrystal by Dispersive Readout

We establish a testbed system for the development of high-sensitivity Electron Spin Resonance (ESR) techniques for small samples at cryogenic temperatures. Our system consists of a Niobium Nitride thin-film planar superconducting microresonator designed to have a concentrated mode volume to couple to a small amount of paramagnetic material, and to be resilient to magnetic fields of up to 400 mT. At 65 mK we measure high-cooperativity coupling ($C \approx 19$) to an organic radical microcrystal containing $10^{12}$ spins in a pico-litre volume. We detect the spin-lattice decoherence rate via the dispersive frequency shift of the resonator. Techniques such as these could be suitable for applications in quantum information as well as for pulsed ESR interrogation of very few spins and could provide insights into the surface chemistry of, for example, the material defects in superconducting quantum processors.

quant-ph↗

arXiv2018

Uniform doping of graphene close to the charge neutrality point by polymer-assisted spontaneous assembly of molecular dopants

Tuning the charge carrier density of two-dimensional (2D) materials by incorporating dopants into the crystal lattice is a challenging task. An attractive alternative is the surface transfer doping by adsorption of molecules on 2D crystals, which can lead to ordered molecular arrays. However, such systems, demonstrated in ultra-high vacuum conditions (UHV), are often unstable in ambient conditions. Here we show that air-stable doping of epitaxial graphene on SiC - achieved by spin-coating deposition of 2,3,5,6-tetrafluoro-tetracyano-quino-dimethane (F4TCNQ) incorporated in poly (methyl-methacrylate) - proceeds via the spontaneous accumulation of dopants at the graphene-polymer interface and by the formation of a charge-transfer complex that yields low-disorder, charge-neutral graphene with carrier mobilities ~70,000 cm2/Vs at cryogenic temperatures. The assembly of dopants on 2D materials assisted by a polymer matrix, demonstrated by spin coating wafer-scale substrates in ambient conditions, opens up a scalable technological route towards expanding the functionality of 2D materials.

cond-mat.mes-hall↗