arXiv subjects

S. Ya. Kilin

Publications and source records attributed to S. Ya. Kilin.

11 recordsLinked to original sources

arXiv2026

Squeezing for dispersive readout of NV magnetometer

Nitrogen vacancy centers in diamond have established themselves as good sensing element for various type of sensors. In particular magnetometers based on diamond impurities are quickly developing and are already on the market. Yet, optical readout in these systems complicates system design. Recently schemes of dispersive readout of nitrogen vacancy spin state using high finesse dielectric cavities for microwave field were proposed, which do not use the optical readout scheme. However, only shot noise based estimates were so far done for sensitivity of these devices. Here we provide detailed analysis of various practically relevant noise and loss sources for such a system. Furthermore, we consider the possibility of using the squeezing quantum state of the probing microwave field and show it allows to improve the device performance even at room temperature.

quant-ph↗

arXiv2025

Dispersive readout with two orthogonal modes of a dielectric cavity

Nitrogen-vacancy color centers in diamond have proven themselves as a good, sensitive element for the measurement of magnetic fields. While the mainstream of magnetometers based on NV centers uses so-called optically detected magnetic resonance, there has recently been a suggestion to use dispersive readout of a dielectric cavity to enhance the sensitivity of magnetometers. Here, we demonstrate that the dispersive readout approach can be significantly improved if a two-channel scheme is considered.

quant-ph↗

arXiv2025

Double electron resonance with two ensembles of nitrogen-vacancy centers in diamond

Nitrogen-vacancy (NV) centers in diamond are widely used in the development of a number of sensors. The sensitivity of these devices is limited by both the number of centers used and their coherent properties. While the effects on the coherent properties of paramagnetic impurities such as carbon 13-isotopes and p1 centers are rather well understood, the mutual interaction of NV centers, which becomes especially important in relatively dense NV ensembles, is less well understood. Here, we provide a systematic study of NV-NV interaction using a dynamical double electron-electron resonance sequence, making it possible to directly observe the interaction of NV centers. Two types of dynamical DEER sequences were considered, consisting of 3 and 4 pulses. The nature of the phase jump in the 3-pulse sequence was attributed to the effect of non-commuting rotations within the sequence. Both the phase of the state vector rotation and its amplitude decay were studied, thus presenting a complete picture of decoherence due to NV-NV interaction. It was shown that the rate of the state vector decay differed significantly from predictions for a spin 1/2 system. However, the decay rate observed in the DEER sequence remained a reliable indicator of the concentration of bath spins and could be used to measure NV center concentration, provided that the magnetic transition of NV centers is saturated.

quant-ph↗

arXiv2025

Bichromatic microwave manipulation of the NV center nuclear spin using transition not detectable via optically detected magnetic resonance

Recently, rotation sensors utilizing the nuclear spins of nitrogen-vacancy color centers in diamond have been demonstrated. However, these devices are power-intensive and challenging to integrate into small chip-based radiofrequency antennas and circuits necessary for controlling nuclear spins or producing relatively high magnetic fields. To address this issue, the coherent manipulation of nuclear spins via coherent population trapping at moderate magnetic fields using microwave fields has been successfully demonstrated in isotopically pure diamond. In this work, we demonstrate that a similar technique can be applied to a diamond plate with a natural abundance of carbon-13, which holds significant potential for practical sensing applications. Although the forbidden resonances required for coherent control were only partially observed, coherent population trapping was successfully demonstrated at both visible and invisible transitions, with an apparent contrast of up to 98+-11% and a true contrast of approximately 35+-7%. This finding confirms the feasibility of coherent nuclear spin control even in diamond plates with naturally occurring carbon-13

quant-ph↗

arXiv2024

Optimization of the sensitivity of a temperature sensor based on germanium-vacancy color center (GeV) in diamond

Temperature sensors based on the GeV color center in diamond are gaining considerable attention in both scientific and industrial fields. For widespread industrial adoption, however, these sensors need a design that is as simple and cost-effective as possible. The original sensor design relied on measuring the spectral characteristics of the zero-phonon line. Recently, a modified approach was introduced, which involves splitting the GeV emission with a dichroic mirror and determining temperature based on the ratio of the two resulting signals. In this analysis, we provide a detailed comparison of both methods. At room temperature, the two methods show comparable performance, with slight variations depending on component quality. However, at temperatures around 300 °C, the new method's performance is estimated to be nearly twice that of the original, provided optimal filter parameters are used. Additionally, the sensitivity of the new method remains roughly consistent with its performance at room temperature.

physics.ins-det↗

arXiv2017

Non-flipping 13C spins in NV diamond: Hyperfine and Spatial Characteristics by DFT Simulation of the C510[NV]H252 Cluster

Single NV centers in diamond coupled by hyperfine interaction to neighboring 13C nuclear spins are now widely used in the emerging quantum technologies as elements of quantum memory adjusted to NV center electron spin qubit. For nuclear spins with low flip-flop rate, single shot readout was demonstrated under ambient conditions. Here we report on the systematic search of such stable NV-13C systems using density functional theory (DFT) to simulate hyperfine and spatial characteristics of all possible NV-13C complexes in the H-terminated cluster C510 [NV]-H252 hosting the NV center. Along with the expected stable NV- axial 13C systems wherein the 13C nuclear spin is located on the NV axis, we found for the first time new families of positions for the 13C nuclear spin exhibiting negligible hyperfine-induced flipping rates due to near-symmetric local spin density distribution. Spatially, these positions are located in the diamond bilayer passing through the vacancy of the NV center and being perpendicular to the NV axis. Analysis of available publications showed that, apparently, some of the predicted non-axial near-stable systems NV-13C have already been observed experimentally. A special experiment done on one of these systems confirmed the prediction made

quant-ph↗

arXiv2017

Afterpulsing model based on the quasi-continuous distribution of deep levels in single-photon avalanche diodes

We have performed a statistical characterization of the effect of afterpulsing in a free-running silicon single-photon detector by measuring the distribution of afterpulse waiting times in response to pulsed illumination and fitting it by a sum of exponentials. We show that a high degree of goodness of fit can be obtained for 5 exponentials, but the physical meaning of estimated characteristic times is dubious. We show that a continuous limit of the sum of exponentials with a uniform density between the limiting times gives excellent fitting results in the full range of the detector response function. This means that in certain detectors the afterpulsing is caused by a continuous band of deep levels in the active area of the photodetector.

quant-ph↗

arXiv2012

Single-atom laser generates nonlinear coherent states

The stationary state of a single-atom (single-qubit) laser is shown to be a phase-averaged nonlinear coherent state - an eigenstate of a specific deformed annihilation operator. The solution found for the stationary state is unique and valid for all regimes of the single-qubit laser operation. We have found the parametrization of the deformed annihilation operator which provides superconvergence in finding the stationary state by iteration. It is also shown that, contrary to the case of the usual laser with constant Einstein coefficients describing transition probabilities, for the single-atom laser the interaction-induced transition probabilities effectively depend on the field intensity.

quant-ph↗

arXiv2012

Optical qudit-type entanglement creation at long distances by means of small cross-Kerr nonlinearities

Entanglement represents an important resource for quantum information processing, but its generation itself requires physical resources that are limited. We propose a scheme for generating a wide class of entangled qudit-type states of optical field modes at sites separated by noisy medium when only weak optical nonlinearities are available at both sites. The protocol is also based on exploiting a weak probe field, transmitted between the sites and used for generation of quantum correlations between two spatially separated field modes. The idea of probabilistic entanglement enhancement by measurement is discussed, and corresponding scheme for measuring the probe field state with linear optics and photodetectors not resolving photon numbers is proposed. It is shown that the protocol is applicable in the case when decoherence, limited efficiency and dark counts of photodetectors, and uncertainty of nonlinear coupling constants are present.

quant-ph↗

arXiv2002

Optimal dimensionality for quantum cryptography

We perform a comparison of two protocols for generating a cryptographic key composed from d-valued symbols: one exploiting a string of independent qubits and another one utilizing d-level systems prepared in states belonging to d+1 mutually unbiased bases. We show that the protocol based on qubits is optimal for quantum cryptography, since it provides higher security and higher key generation rate.

quant-ph↗

arXiv1999

Quantum Teleportation Using Quantum Non-Demolition Technique

We propose a new scheme and protocol for quantum teleportation of a single-mode field state, based on entanglement produced by quantum non-demolition interaction. We show that the recently attained results in QND technique allow to perform the teleportation in quantum regime. We also show that applying QND coupling to squeezed fields will significantly improve the quality of teleportation for a given degree of squeezing.

quant-ph↗