arXiv subjects

Eugeniy Mikhailov

Publications and source records attributed to Eugeniy Mikhailov.

7 recordsLinked to original sources

arXiv2025

Electron beam characterization via fluorescence imaging of Rydberg states in atomic vapor

We demonstrate an all-optical, minimally invasive method for electron beam (e-beam) characterization using Rydberg electrometry. The e-beam passes through a dilute Rb vapor prepared in a quantum superposition of ground and Rydberg states that reduces resonant absorption in a narrow spectral region. Imaging the modifications of Rb fluorescence due to shifts in the Rydberg state from the e-beam electric field allows us to reconstruct e-beam width, centroid position, and current. We experimentally demonstrate this technique using a 20 keV e-beam in the range of currents down to 20 $μ$A, and discuss technical challenges produced by environmental electric potentials in the detection chamber. Overall, we demonstrate the promising potential of such an approach as a minimally invasive diagnostic for charged particle beams.

physics.atom-ph↗

arXiv2023

Rydberg Raman-Ramsey (R${}^3$) resonances in atomic vapor

The sensitivity of electric field sensors based on two-photon electromagnetically induced transparency (EIT) involving highly excited Rydberg states in thermal atoms is often limited by the residual Doppler effect and optical power broadening. Here, we propose a method to reduce the EIT spectral linewidth using a Ramsey interrogation approach, allowing multiple interrogations of atomic coherence, using either temporally or spatially separated laser beams. Our theoretical calculations predict that the linewidth of such Raman-Ramsey spectral features can be substantially reduced compare to a standard Doppler-broadened EIT, opening a possibility to improved sensitivity of Rydberg atomic vapor-based sensors. We also discuss some preliminary experimental efforts toward observing Raman-Ramsey resonances for both spatially and temporally separated interrogation approaches and associated technical challenges.

physics.atom-ph↗

arXiv2021

Beyond the Petermann limit: can exceptional points increase sensor precision?

Experiments near the lock-in region in maximally dissipative non-Hermitian systems, e.g., conventional laser gyroscopes near the deadband, have run up against the Petermann limit, where excess noise exactly cancels any scale-factor enhancement resulting in no overall enhancement in precision. As a result, one might be tempted to conclude that exceptional points (EPs) generally cannot be used to increase the precision of laser sensors. Indeed, using a linear eigenmode analysis we show that the Petermann limit applies not just to maximally dissipative systems, but for any type of EP, owing to the fact that EPs are rotationally invariant. It turns out, however, that this restriction comes from the assumption of linearity. We find that nonlinearity breaks the rotation symmetry such that the different types of EPs are no longer equivalent above threshold. In particular, for sufficiently high measurement frequencies, EPs in conservatively coupled systems having a saturation imbalance can lead to an increase in the fundamental precision beyond the Petermann limit. Importantly, we find that only one mode lases under these conditions. We show that the beat note can be recovered by interference with an auxiliary mode, but that this has consequences for the quantum and classical noise that depend on the recovery scheme. Thus, it remains to be seen whether practical experiments can be designed that can take advantage of this enhancement.

physics.optics↗

arXiv2019

Measurements with prediction and retrodiction on the collective spin of 10^{11} atoms beat the standard quantum limit

Quantum probes using $N$ uncorrelated particles give a limit on the measurement sensitivity referred to as the standard quantum limit (SQL). The SQL, however, can be overcome by exploiting quantum entangled states, such as spin squeezed states. We report generation of a quantum state, that surpasses the SQL for probing of the collective spin of $10^{11}$ $\text{Rb}$ atoms contained in a vapor cell. The state is prepared and verified by sequences of stroboscopic quantum non-demolition (QND) measurements, and we apply the theory of past quantum states to obtain the spin state information from the outcomes of both earlier and later QND measurements. In this way, we obtain a conditional noise reduction of 5.6 dB, and a metrologically-relevant squeezing of $4.5\pm0.40~\text{dB}$. The past quantum state yields tighter information on the spin component than we can obtain by a conventional QND measurement. Our squeezing results are obtained with 1000 times more atoms than in any previous experiments with a corresponding record $4.6\times10^{-13} rad^2$ variance of the angular fluctuations of a squeezed collective spin.

quant-ph↗

arXiv2018

Spatial multiplexing of squeezed light by coherence diffusion

Spatially splitting nonclassical light beams is in principle prohibited due to noise contamination during beam splitting. We propose a platform based on thermal motion of atoms to realize spatial multiplexing of squeezed light. Light channels of separate spatial modes in an anti-relaxation coated vapor cell share the same long-lived atomic coherence jointly created by all channels through the coherent diffusion of atoms which in turn enhances individual channel's nonlinear process responsible for light squeezing. Consequently, it behaves as squeezed light in one optical channel transferring to other distant channels even with laser powers below the threshold for squeezed light generation. An array of squeezed light beams was created with low laser power $\sim\text{mW}$. This approach holds great promise for applications in multi-node quantum network and quantum enhanced technologies such as quantum imaging and sensing.

quant-ph↗

arXiv2017

Gaussian Beam-Propagation Theory for Nonlinear Optics - Featuring an Exact Treatment of Orbital Angular Momentum Transfer

We present a general, Gaussian spatial mode propagation formalism for describing the generation of higher order multi-spatial-mode beams generated during nonlinear interactions. Furthermore, to implement the theory, we simulate optical angular momentum transfer interactions, and show how one can optimize the interaction to reduce the undesired modes. Past theoretical treatments of this problem have often been phenomenological, at best. Here we present an exact solution for the single-pass no-cavity regime, in which the the nonlinear interaction is not overly strong. We apply our theory to two experiments, with very good agreement, and give examples of several more configurations, easily tested in the laboratory.

physics.optics↗

arXiv2005

Quantum Noise Locking

Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, can not rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squeezed and anti-squeezed lock points. Experimental data for the NL technique both in the presence and absence of coherent fields are shown, including a comparison with coherent locking techniques. Finally, we use NL to enable a stable readout of the squeezed vacuum state on a homodyne detector.

quant-ph↗