We investigate the radiative coupling between two two-level atoms with arbitrarily polarized dipoles in the vicinity of a nanofiber. We present a systematic derivation for the master equation, the single- and cross-atom decay coefficients, and the dipole-dipole interaction coefficients for the atoms interacting with the vacuum of the field in the guided and radiation modes of the nanofiber. We study numerically the case where the atomic dipoles are circularly polarized. In this case, the rate of emission depends on the propagation direction along the fiber axis and, hence, the radiative interaction between the atoms is chiral. We examine the time evolution of the atoms for different initial states. We calculate the fluxes and mean numbers of photons spontaneously emitted into guided modes in the positive and negative directions of the fiber axis. We show that the chiral radiative coupling modifies the collective emission of the atoms. We observe that the modifications strongly depend on the initial state of the atomic system, the radiative transfer direction, the distance between the atoms, and the distance from the atoms to the fiber surface.We investigate the radiative coupling between two two-level atoms with arbitrarily polarized dipoles in the vicinity of a nanofiber. We present a systematic derivation for the master equation, the single- and cross-atom decay coefficients, and the dipole-dipole interaction coefficients for the atoms interacting with the vacuum of the field in the guided and radiation modes of the nanofiber. We study numerically the case where the atomic dipoles are circularly polarized. In this case, the rate of emission depends on the propagation direction along the fiber axis and, hence, the radiative interaction between the atoms is chiral. We examine the time evolution of the atoms for different initial states. We calculate the fluxes and mean numbers of photons spontaneously emitted into guided modes in the positive and negative directions of the fiber axis. We show that the chiral radiative coupling modifies the collective emission of the atoms. We observe that the modifications strongly depend on the initial state of the atomic system, the radiative transfer direction, the distance between the atoms, and the distance from the atoms to the fiber surface.

Physical Review AFeb 24, 201750 citations

Chiral excitation of a single atom by a quantized single-photon pulse in a guided mode of a nanofiber

Fam Le Kien, Síle Nic Chormaic, Thomas Busch

We study the interaction between a single two-level atom and a quantized single-photon probe pulse in a guided mode of a nanofiber. We examine the situation of chiral interaction, where the atom has a dipole rotating in the meridional plane of the nanofiber and the probe pulse is quasilinearly polarized along the radial direction of the atom position in the fiber transverse plane. We show that the atomic excitation probability, the photon transmission flux, and the photon transmission probability depend on the propagation direction of the probe pulse along the fiber axis. In contrast, the reflection flux and the reflection probability do not depend on the propagation direction of the probe pulse. We find that, unlike the atomic excitation probability, the asymmetry parameter for this characteristic does not vary in time and does not depend on the probe pulse shape.We study the interaction between a single two-level atom and a quantized single-photon probe pulse in a guided mode of a nanofiber. We examine the situation of chiral interaction, where the atom has a dipole rotating in the meridional plane of the nanofiber and the probe pulse is quasilinearly polarized along the radial direction of the atom position in the fiber transverse plane. We show that the atomic excitation probability, the photon transmission flux, and the photon transmission probability depend on the propagation direction of the probe pulse along the fiber axis. In contrast, the reflection flux and the reflection probability do not depend on the propagation direction of the probe pulse. We find that, unlike the atomic excitation probability, the asymmetry parameter for this characteristic does not vary in time and does not depend on the probe pulse shape.

arXiv:2002.01596Physical Review AJun 11, 20202 citations

Direction-dependent coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition

Fam Le Kien, Síle Nic Chormaic, Thomas Busch

We study the directional dependence of the coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition. We examine the situation where the nanofiber is aligned along the $z$ axis, the atom lies on the fiber transverse $x$ axis, the quantization axis for the atomic internal states is the other orthogonal transverse $y$ axis, the atomic upper and lower levels are the magnetic sublevels ${M}^{\ensuremath{'}}$ and $M$ of hyperfine-structure levels of an alkali-metal atom, and the field is in a quasilinearly polarized fundamental guided mode ${\mathrm{HE}}_{11}$ with the polarization $\ensuremath{\xi}=x$ or $y$ . We find that the absolute value of the quadrupole Rabi frequency depends on the propagation direction of the light field in the cases of (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}1, \ensuremath{\xi}=y$) and (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}2, \ensuremath{\xi}=x$). We show that the directional dependence of the coupling leads to the directional dependence of spontaneous emission into guided modes. We find that the directional dependence of the atom-field coupling in the case of quadrupole transitions is not entirely due to spin-orbit coupling of light: there are some other contributions resulting from the gradient of the spatial phase factor of the field.We study the directional dependence of the coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition. We examine the situation where the nanofiber is aligned along the $z$ axis, the atom lies on the fiber transverse $x$ axis, the quantization axis for the atomic internal states is the other orthogonal transverse $y$ axis, the atomic upper and lower levels are the magnetic sublevels ${M}^{\ensuremath{'}}$ and $M$ of hyperfine-structure levels of an alkali-metal atom, and the field is in a quasilinearly polarized fundamental guided mode ${\mathrm{HE}}_{11}$ with the polarization $\ensuremath{\xi}=x$ or $y$. We find that the absolute value of the quadrupole Rabi frequency depends on the propagation direction of the light field in the cases of (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}1, \ensuremath{\xi}=y$) and (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}2, \ensuremath{\xi}=x$). We show that the directional dependence of the coupling leads to the directional dependence of spontaneous emission into guided modes. We find that the directional dependence of the atom-field coupling in the case of quadrupole transitions is not entirely due to spin-orbit coupling of light: there are some other contributions resulting from the gradient of the spatial phase factor of the field.

arXiv:2211.06000Physical Review AJan 19, 20234 citations

Controlling Radiative Properties of Circular Atomic Arrays through Nanofiber Guided Modes

Juliette Jiménez Jaimes, Síle Nic Chormaic, E. Brion

We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber (ONF). Our study reveals that the radiation eigenmodes (REMs) of a single ring selectively couple to specific guided modes of the fiber, depending on their symmetry. By tuning the physical parameters of the system, we demonstrate that the emission towards radiation modes can be highly suppressed, thereby enhancing the lifetime of the atomic excitation. Two identical rings positioned at a distance from each other along the nanofiber can exchange an excitation even at large separations through nanofiber guided modes. This results in enhanced sub-and super-radiance compared to the single-ring case. The selective coupling of REMs to specific guided modes and the enhanced sub-and super-radiance in a two-ring system suggest that the ring configuration is promising for implementing efficient and versatile light-matter nanofiber-based interfaces and achieving waveguide quantum electrodynamics (WQED).We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber (ONF). Our study reveals that the radiation eigenmodes (REMs) of a single ring selectively couple to specific guided modes of the fiber, depending on their symmetry. By tuning the physical parameters of the system, we demonstrate that the emission towards radiation modes can be highly suppressed, thereby enhancing the lifetime of the atomic excitation. Two identical rings positioned at a distance from each other along the nanofiber can exchange an excitation even at large separations through nanofiber guided modes. This results in enhanced sub-and super-radiance compared to the single-ring case. The selective coupling of REMs to specific guided modes and the enhanced sub-and super-radiance in a two-ring system suggest that the ring configuration is promising for implementing efficient and versatile light-matter nanofiber-based interfaces and achieving waveguide quantum electrodynamics (WQED).

EPJ Web of ConferencesJan 1, 20260 citations

Collective emission of atomic nanorings around an optical nanofiber

Juliette Jiménez Jaimes, Síle Nic Chormaic, E. Brion

We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber. We show that the radiation eigenmodes of a single ring selectively couple to specific guided modes of the fiber, according to their symmetry, and study how the physical parameters of the system control their nature. In particular, we identify situations in which the emission toward radiation modes is highly suppressed with respect to fiber-guided modes while the lifetime of the atomic excitation is enhanced. We further address the case of two identical nanorings positioned at a distance from each other along the nanofiber. By contrast to free-space configurations, the rings can exchange excitations even at large separation through nanofiber guided modes resulting in enhanced sub- and super-radiance with respect to the single-ring case. Our findings suggest that the ring configuration is promising for the implementation of efficient and versatile light-matter nanofiber-based interfaces and the achievement of waveguide quantum electrodynamics.We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber. We show that the radiation eigenmodes of a single ring selectively couple to specific guided modes of the fiber, according to their symmetry, and study how the physical parameters of the system control their nature. In particular, we identify situations in which the emission toward radiation modes is highly suppressed with respect to fiber-guided modes while the lifetime of the atomic excitation is enhanced. We further address the case of two identical nanorings positioned at a distance from each other along the nanofiber. By contrast to free-space configurations, the rings can exchange excitations even at large separation through nanofiber guided modes resulting in enhanced sub- and super-radiance with respect to the single-ring case. Our findings suggest that the ring configuration is promising for the implementation of efficient and versatile light-matter nanofiber-based interfaces and the achievement of waveguide quantum electrodynamics.

arXiv:2506.16909Jun 20, 20250 citations

Controlling radiative properties of circular atomic arrays through nanofiber guided modes

Juliette Jiménez Jaimes, Síle Nic Chormaic, E. Brion

We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber. We show that the radiation eigenmodes of a single ring selectively couple to specific guided modes of the fiber, according to their symmetry, and study how the physical parameters of the system control their nature. In particular, we identify situations in which the emission toward radiation modes is highly suppressed with respect to fiber guided modes while the lifetime of the atomic excitation is enhanced. We further address the case of two identical rings positioned at a distance from each other along the nanofiber. By contrast to free-space configurations, the rings can exchange an excitation even at large separation through nanofiber guided modes resulting in enhanced sub- and supper-radiance with respect to the single-ring case. Our findings suggest that the ring configuration is promising for the implementation of efficient and versatile light-matter nanofiber-based interfaces and the achievement of waveguide quantum electrodynamics.We theoretically investigate the collective emission of one and two circular arrays of two-level atoms surrounding an optical nanofiber. We show that the radiation eigenmodes of a single ring selectively couple to specific guided modes of the fiber, according to their symmetry, and study how the physical parameters of the system control their nature. In particular, we identify situations in which the emission toward radiation modes is highly suppressed with respect to fiber guided modes while the lifetime of the atomic excitation is enhanced. We further address the case of two identical rings positioned at a distance from each other along the nanofiber. By contrast to free-space configurations, the rings can exchange an excitation even at large separation through nanofiber guided modes resulting in enhanced sub- and supper-radiance with respect to the single-ring case. Our findings suggest that the ring configuration is promising for the implementation of efficient and versatile light-matter nanofiber-based interfaces and the achievement of waveguide quantum electrodynamics.

Physical Review AOct 1, 20252 citations

z

axis, the atom lies on the fiber transverse

x

axis, the quantization axis for the atomic internal states is the other orthogonal transverse

y

axis, the atomic upper and lower levels are the magnetic sublevels ${M}^{\ensuremath{'}}$ and

M

of hyperfine-structure levels of an alkali-metal atom, and the field is in a quasilinearly polarized fundamental guided mode

{\mathrm{HE}}_{11}

with the polarization $\ensuremath{\xi}=x$ or

y

. We find that the absolute value of the quadrupole Rabi frequency depends on the propagation direction of the light field in the cases of (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}1, \ensuremath{\xi}=y$) and (${M}^{\ensuremath{'}}\ensuremath{-}M=\ifmmode\pm\else\textpm\fi{}2, \ensuremath{\xi}=x$). We show that the directional dependence of the coupling leads to the directional dependence of spontaneous emission into guided modes. We find that the directional dependence of the atom-field coupling in the case of quadrupole transitions is not entirely due to spin-orbit coupling of light: there are some other contributions resulting from the gradient of the spatial phase factor of the field.