Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2607.18617

Spontaneous optical emission of a randomly oriented chiral quantum source

Mikael P. Backlund

quant-phphysics.chem-phphysics.opticsSubmitted Jul 21, 2026• Announced Jul 22, 2026• 0 citations
arXivHTMLPDF

Abstract

We derive the form of the one-photon state of the electromagnetic field resulting from spontaneous optical emission of a randomly oriented chiral quantum source, including electric dipole, magnetic dipole, and electric quadrupole contributions to the radiation. We describe how spatial coherence in the emission can be exploited to reveal hidden information about the emitter. This work serves as a prelude and companion piece to our concurrently submitted work \cite{Backlund2026Letter} in which we present the classical and quantum error bounds associated with assigning the handedness of such an emitter.

Related papers

Coherence Bounds on Mean Dipole Radiation from Quantum Emitters

Daniel Scretching

This paper clarifies the limits of representing spontaneous emission with a classical electromagnetic field sourced only by an atom’s mean dipole. Extending a pure-state hydrogen result to an arbitrary two-level density matrix, it separates total radiated power from the portion attributable to optical coherence. Under the electric-dipole, rotating-wave, Markov, and free-space approximations, positivity of the density matrix places a strict upper bound on the coherent fraction of the emitted intensity. The remainder is necessarily associated with quantum dipole fluctuations rather than the classical mean field. A hydrogen benchmark and ensemble structure-factor analysis illustrate how excited-state population, coherence, and radiation can be measured and tested independently. The result provides a diagnostic boundary for semiclassical Maxwell–Scretching Chain (MSC) and Scretching Quantum Chain (SQC) source models while remaining consistent with established spontaneous-emission theory rather than proposing a new emission law.

•Sep 29, 2026•0 citations

Quantum limits to chiroptical molecular discrimination

Mikael P. Backlund

Discriminating enantiomer pairs is of central importance in the molecular sciences. The preferential interaction between chiral light and matter is commonly employed in this discrimination, despite fundamental challenges. Here we present quantitative error bounds for classifying the handedness of a chiral, randomly oriented, quantum optical emitter from the perspective of classical and quantum hypothesis testing. Most interestingly, we find that a collective measurement on $N$ photons can provide an orders-of-magnitude improvement in error rate relative to a corresponding separable measurement.

quant-pharXiv:2607.19136•Jul 22, 2026•0 citations

Detailed description of spontaneous emission

Marat Vladimirovich Guryev

The wave side of wave–photon duality, describing light as an electromagnetic field (EMF), is used in this article. The EMF of spontaneous light emission (SE) of a laser-excited atom is calculated from first principles for the first time. This calculation is done using the simple method of atomic quantum electrodynamics. The EMF of SE is also calculated for three types of polyatomic light sources excited by a laser. It is shown that light radiated by such sources can be coherent, which explains recent experiments on SE of laser-excited atoms. Small sources of SE can be superradiant, which also conforms to experiment. Thus, SE is shown not to be a random event itself. Random properties of natural light are simply explained as a result of thermal excitation randomness without additional hypotheses. The EMF of SE is described by simple complex functions, but not real ones.

arXiv:1101.3082•Journal of Modern Optics•Aug 10, 2012•1 citation

Directional spontaneous emission in photonic crystal slabs

Erik Navarro-Barón, Herbert Vinck-Posada, Alejandro González-Tudela

Spontaneous emission is one of the most fundamental out-of-equilibrium processes in which an excited quantum emitter relaxes to the ground state due to quantum fluctuations. In this process, a photon is emitted that can interact with other nearby emitters and establish quantum correlations between them, e.g., via super and subradiance effects. One way to modify these photon-mediated interactions is to alter the dipole radiation patterns of the emitter, e.g., by placing photonic crystals near them. One recent example is the generation of strong directional emission patterns - key to enhancing super and subradiance effects - in two dimensions by employing photonic crystals with band structures characterized by linear isofrequency contours and saddle points. However, these studies have predominantly used oversimplified toy models, overlooking the electromagnetic field's intricacies in actual materials, including aspects like geometrical dependencies, emitter positions, and polarization. Our study delves into the interaction between these directional emission patterns and the variables mentioned above, revealing the untapped potential to fine-tune collective quantum optical phenomena.

Nanophotonics•Feb 24, 2024•6 citations

Directional spontaneous emission in photonic crystal slabs

Erik Navarro-Barón, Herbert Vinck-Posada, Alejandro González-Tudela

Spontaneous emission is one of the most fundamental out-of-equilibrium processes in which an excited quantum emitter relaxes to the ground state due to quantum fluctuations. In this process, a photon is emitted that can interact with other nearby emitters and establish quantum correlations between them, e.g., via super and subradiance effects. One way to modify these photon-mediated interactions is to alter the dipole radiation patterns of the emitter, e.g., by placing photonic crystals near them. One recent example is the generation of strong directional emission patterns-key to enhancing super and subradiance effects-in two dimensions by employing photonic crystals with band structures characterized by linear isofrequency contours and saddle-points. However, these studies have predominantly used oversimplified toy models, overlooking the electromagnetic field's intricacies in actual materials, including aspects like geometrical dependencies, emitter positions, and polarization. Our study delves into the interaction between these directional emission patterns and the aforementioned variables, revealing the untapped potential to fine-tune collective quantum optical phenomena.

arXiv:2312.01971•Dec 4, 2023•0 citations

QED in optically active media: Enhanced spontaneous emission and chiral, yet parity-conserving, corrections to the electron mass

Karl-Peter Marzlin

The electromagnetic field inside an isotropic optically active medium is quantized on the base of Fedorov's model for optical activity. The modified photon propagator is derived. Using this result it is shown that the QED correction to the electron mass contains chiral terms which nevertheless are parity invariant. The spontaneous emission rate of a two-level atom is shown to increase in the medium. The spontaneously emitted radiation is partially polarized. \textcopyright{} 1996 The American Physical Society.

arXiv:hep-ph/9602254•Physical Review A•Apr 1, 1996•4 citations
We derive the form of the one-photon state of the electromagnetic field resulting from spontaneous optical emission of a randomly oriented chiral quantum source, including electric dipole, magnetic dipole, and electric quadrupole contributions to the radiation. We describe how spatial coherence in the emission can be exploited to reveal hidden information about the emitter. This work serves as a prelude and companion piece to our concurrently submitted work \cite{Backlund2026Letter} in which we present the classical and quantum error bounds associated with assigning the handedness of such an emitter.
This paper clarifies the limits of representing spontaneous emission with a classical electromagnetic field sourced only by an atom’s mean dipole. Extending a pure-state hydrogen result to an arbitrary two-level density matrix, it separates total radiated power from the portion attributable to optical coherence. Under the electric-dipole, rotating-wave, Markov, and free-space approximations, positivity of the density matrix places a strict upper bound on the coherent fraction of the emitted intensity. The remainder is necessarily associated with quantum dipole fluctuations rather than the classical mean field. A hydrogen benchmark and ensemble structure-factor analysis illustrate how excited-state population, coherence, and radiation can be measured and tested independently. The result provides a diagnostic boundary for semiclassical Maxwell–Scretching Chain (MSC) and Scretching Quantum Chain (SQC) source models while remaining consistent with established spontaneous-emission theory rather than proposing a new emission law.
Discriminating enantiomer pairs is of central importance in the molecular sciences. The preferential interaction between chiral light and matter is commonly employed in this discrimination, despite fundamental challenges. Here we present quantitative error bounds for classifying the handedness of a chiral, randomly oriented, quantum optical emitter from the perspective of classical and quantum hypothesis testing. Most interestingly, we find that a collective measurement on NNN photons can provide an orders-of-magnitude improvement in error rate relative to a corresponding separable measurement.
The wave side of wave–photon duality, describing light as an electromagnetic field (EMF), is used in this article. The EMF of spontaneous light emission (SE) of a laser-excited atom is calculated from first principles for the first time. This calculation is done using the simple method of atomic quantum electrodynamics. The EMF of SE is also calculated for three types of polyatomic light sources excited by a laser. It is shown that light radiated by such sources can be coherent, which explains recent experiments on SE of laser-excited atoms. Small sources of SE can be superradiant, which also conforms to experiment. Thus, SE is shown not to be a random event itself. Random properties of natural light are simply explained as a result of thermal excitation randomness without additional hypotheses. The EMF of SE is described by simple complex functions, but not real ones.
Spontaneous emission is one of the most fundamental out-of-equilibrium processes in which an excited quantum emitter relaxes to the ground state due to quantum fluctuations. In this process, a photon is emitted that can interact with other nearby emitters and establish quantum correlations between them, e.g., via super and subradiance effects. One way to modify these photon-mediated interactions is to alter the dipole radiation patterns of the emitter, e.g., by placing photonic crystals near them. One recent example is the generation of strong directional emission patterns - key to enhancing super and subradiance effects - in two dimensions by employing photonic crystals with band structures characterized by linear isofrequency contours and saddle points. However, these studies have predominantly used oversimplified toy models, overlooking the electromagnetic field's intricacies in actual materials, including aspects like geometrical dependencies, emitter positions, and polarization. Our study delves into the interaction between these directional emission patterns and the variables mentioned above, revealing the untapped potential to fine-tune collective quantum optical phenomena.
Spontaneous emission is one of the most fundamental out-of-equilibrium processes in which an excited quantum emitter relaxes to the ground state due to quantum fluctuations. In this process, a photon is emitted that can interact with other nearby emitters and establish quantum correlations between them, e.g., via super and subradiance effects. One way to modify these photon-mediated interactions is to alter the dipole radiation patterns of the emitter, e.g., by placing photonic crystals near them. One recent example is the generation of strong directional emission patterns-key to enhancing super and subradiance effects-in two dimensions by employing photonic crystals with band structures characterized by linear isofrequency contours and saddle-points. However, these studies have predominantly used oversimplified toy models, overlooking the electromagnetic field's intricacies in actual materials, including aspects like geometrical dependencies, emitter positions, and polarization. Our study delves into the interaction between these directional emission patterns and the aforementioned variables, revealing the untapped potential to fine-tune collective quantum optical phenomena.
The electromagnetic field inside an isotropic optically active medium is quantized on the base of Fedorov's model for optical activity. The modified photon propagator is derived. Using this result it is shown that the QED correction to the electron mass contains chiral terms which nevertheless are parity invariant. The spontaneous emission rate of a two-level atom is shown to increase in the medium. The spontaneously emitted radiation is partially polarized. \textcopyright{} 1996 The American Physical Society.