arXiv subjects

Christian Drago

Publications and source records attributed to Christian Drago.

5 recordsLinked to original sources

arXiv2026

Two-photon-excited fluorescence spectroscopy of Rb atoms in a magneto-optical trap

We report the results of two-photon-excited fluorescence (TPEF) measurements of the $5\mathrm{S}_{1/2} \rightarrow 5\mathrm{D}_{5/2}$ transition of $^{85}$Rb and $^{87}$Rb cooled in a magneto-optical trap (MOT). We observe TPEF at excitation powers as low as 1 $\mu$W or fluxes as low as $2.98_{-0.94}^{+1.37} \times 10^{18}\ \text{photons}\,\text{cm}^{-2}\,\text{s}^{-1}$ ($^{85}$Rb) and $3.31_{-1.33}^{+2.21} \times 10^{18}\ \text{photons}\,\text{cm}^{-2}\,\text{s}^{-1}$ ($^{87}$Rb). Our results demonstrate that optically cooled Rb is a promising platform for observing sensitive two-photon spectral signatures at low photon fluxes.

physics.atom-ph↗

arXiv2025

Photodetection of Squeezed Light: a Whittaker-Shannon Analysis

The Whittaker-Shannon decomposition provides a temporally localized description of squeezed light, making it applicable in the CW limit and leading to a definition of squeezing strength based on the number of photon pairs at a time. We show examples of its usefulness by calculating quadrature variance in a homodyne detection scheme, coincidence detection probabilities in the continuous-wave limit, and analyzing the Hong-Ou-Mandel effect for strongly squeezed light. Quadrature uncertainty falls farther below the shot noise limit when squeezing is strong, but effects due to correlations between photon pairs are most significant with weak squeezing. Our analysis extends previous results to more general scenarios, and we leverage the Whittaker-Shannon formalism to interpret them based on the temporal properties of photon pairs.

quant-ph↗

arXiv2025

Fluorescence driven by nonclassical light

We investigate whether or not irradiation by squeezed light can provide an enhancement of the two-photon excitation of a system over irradiation by classical light. Our emphasis is not only on whether or not there is such an enhancement, but also on whether or not any enhancement can be reasonably detected in an experiment. We begin by developing a model that includes radiative and nonradiative broadening to calculate the total scattered and absorbed energy. As an example calculation, we consider cesium atoms in a magneto-optical trap, and evaluate the fluorescence emission when driven by non-degenerate classical and squeezed light, in both the continuous-wave and pulsed regimes. We find that squeezed light can provide an enhancement in both regimes under ideal circumstances. These enhancements are in principle detectable. However, we stress that they are moderate at best compared to recently reported values for molecular systems.

quant-ph↗

arXiv2022

Aspects of Two-photon Absorption of Squeezed Light: the CW limit

We present a theoretical analysis of two-photon absorption of classical and squeezed light valid when one-photon absorption to an intermediate state is either resonant or far-detuned from resonance, and in both the low and high intensity regimes. In this paper we concentrate on continuous-wave excitation, although the approach we develop is more general. We calculate the energy removed from an incident field for typical experimental parameters and consider the limiting cases when the photon pairs are narrowband or broadband compared to the molecular linewidths. We find an enhancement of the two-photon absorption due to resonant contributions from the large squeezed light bandwidth and due to photon bunching in the low intensity regime. However, in both cases, for the parameters we choose, the one-photon absorption is the dominant process in the region of parameter space where a large enhancement of the two-photon absorption is possible.

quant-ph↗

arXiv2022

Tunable frequency-bin multi-mode squeezed states of light

Squeezed states are a versatile class of quantum states with applications ranging from quantum computing to high-precision detection. We propose a method for generating tunable squeezed states of light with multiple modes encoded in frequency bins. Our method uses custom-engineered spontaneous parametric downconversion pumped by a pulse-shaped pump field. The multi-mode squeezed states are generated in a single pass and can be tuned in real time by adjusting the properties of the pump field. Exploring new quantum states of light, encoded in new degrees of freedom, can be a fruitful path toward discovering new quantum applications.

quant-ph↗