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:2604.03148

Localized Photon Absorption in a Single-Crystalline Material

Daniel Kazenwadel, Jacob Holder, Livio Ciorciaro, Noel Neathery, Raphael Schwenzer, Leon Oleschko, Jannik Hertkorn, Margaretha Sandor, Peter Baum

physics.opticscond-mat.str-elquant-phSubmitted Apr 3, 2026• Announced Apr 6, 2026• Revised Jul 7, 2026 (v2)
v1 · Apr 3, 2026v2 · Jul 7, 2026
arXivHTMLPDF

Abstract

The absorption of light is one of the most fundamental processes in condensed-matter physics and optics. Here we investigate under which conditions laser light is absorbed by a crystalline material as an electromagnetic wave with delocalized properties or rather as photons that cause discrete, localized, nanometer-sized consequences. We excite the first-order phase transition of vanadium dioxide with laser pulses of sufficient frequency to overcome the band gap but with insufficient pulse energy to overcome the latent heat. According to Maxwell's equations and Bloch theory, no transition should occur, because nowhere in the material is enough energy. Nevertheless, we observe with ultrafast electron diffraction a disordered crystal geometry with nanometer-sized spots of switched material that grow and diminish with time. The amount of localized spots matches approximately to the number of photons in the absorbed laser wave. Two optical experiments substantiate this phenomenon, and simulations reproduce all measurements results. We discuss whether crystals defects, temperature, or a genuine wavefunction collapse can explain the discovered phenomenon. Practically, the reported absorption mechanism enables local consequences at substantially higher energy than average and provides insight into symmetry breaks and non-thermal fluctuations within complex materials.

Comments
Daniel Kazenwadel, Jacob Holder: equal contribution

Related papers

Laser cooling via excitation of localized electrons

David Emin

Under appropriate conditions, absorption of light by a solid can initiate a process by which it is cooled. In particular, energy is extracted from a material when its absorption of a photon is followed by emission of a photon of higher energy. This up-conversion requires some of the solid's electrons to garner energy from atomic vibrations. Here, two schemes for laser cooling via localized electronic states are addressed. The first scheme utilizes the ground state and an excited state of a localized center. In this two-level scheme, the cooling process is initiated with photon absorption in the extreme low-energy tail of a localized state's vibrationally broadened absorption spectrum. The subsequent atomic relaxation transfers energy of especially large vibratory atomic strains into electrical energy that is then extracted via photon emission. The second scheme involves the ground state and two excited states of a localized center. Cooling is facilitated when (i) the photoexcitation of an electron from its ground state to the lower excited level is followed by (ii) electron-phonon-induced promotion to the uppermost level and the subsequent (iii) return of the electron to its ground state with emission of a photon of higher energy than that of the absorbed photon. However, competing relaxation processes contribute to heating. The net cooling power per unit volume is maximized for both schemes, thereby determining characteristics of localized electronic systems that foster optical cooling. The cooling power per unit volume is greatest at high temperatures and falls rapidly as the thermal energy is reduced below each system's luminescence Stokes shift. Moreover, cooling via the three-level scheme is most effective when (i) the energy separation between excited states is smaller than the thermal energy and (ii) the degeneracy of the highest-lying excited state is much larger than that of the center's middle level. These restrictive conditions appear to be satisfied for the three-level systems that to date exhibit laser cooling at or somewhat below room temperature: severely localized crystal-field-split $f$-electron states of rare-earth ions.

Physical Review B•Jul 6, 2007•8 citations

Designing media for the local control of nanoscale absorption, transmission, and energy transfer

Jamie M. Leeder, Matt M. Coles, Jack Ford +1 more

Interactions between light and molecular matter featuring photon absorption are commonly associated with excitation of individual chromophores. Subsequent relaxation is achieved through numerous mechanisms, such as scattering and energy transfer to neighbouring chromophores. The efficiency of such processes depends on many factors, including the intensity and wavelength of the optical input, the absorption cross-section of the molecule and the relative orientation of molecular components. New photonic materials are developed on the principle that such factors are controllable, duly tailoring the system to suit new technological applications. The parameters that determine the linear response in multicomponent materials are typically assessed within the theoretical framework of classical optics. However, with improved interest and capability in fabricating nanoscale structures (especially those that exhibit quantum effects), it is becoming increasingly relevant to develop theory that more faithfully represents how individual photons engage with matter. In such constructs, the interaction of materials with optical waves and photons is highly dependent on local molecular environment, therefore surrounding structures and ancillary species exert forms of influence on the photophysical processes inherent within dielectric media. At optical wavelengths where the secondary structure displays little intrinsic optical absorption, the role of such components is often interpreted as modifying the input through a corrective local index of refraction. Although expedient in the discussion of bulk properties of a macroscopic medium, it is reasonably supposed at a local chromophore-photon level that optical mechanisms operate in a different fashion. Using a fully quantized approach to the representation of local molecular electronic structure and electrodynamics, this research develops rigorous theory and a corresponding physical interpretation of how photon absorption, scattering and energy transfer are modified by vicinal, non-absorbing chromophores. The results provide insight into the mechanisms achieved within multi-chromophore systems, highlighting factors that assist in the optimization of optical characteristics in designer materials.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 2, 2014•0 citations

Photon Localization in Quantum Field Theory: From Point Detector to Finite-Size Detector

Jinhong Xu

Abstract: Starting from the physical intuition that light (massless fields) is delocalized while massive matter is localized, we develop a three-dimensional quantum field theory model to study photon absorption by a material detector. The detector is modeled as a two-level system coupled to a massless scalar field via a linear interaction. We consider three progressively realistic scenarios: (i) a point-like detector absorbing an s-wave spherical photon, (ii) a point-like detector absorbing a plane-wave photon, and (iii) a finite-size detector with a spatial distribution. Using Fermi's golden rule, we compute the transition rates and absorption cross sections. We show that for a point detector, the absorption cross section for s-wave photons is finite and frequency-independent, and for plane-wave photons it is independent of the incident direction. For a finite-size detector, the absorption efficiency is modulated by a form factor that suppresses absorption when the photon wavelength is shorter than the detector size. This provides a quantitative explanation for why microscopic objects (atoms) absorb light efficiently, while macroscopic objects are transparent or reflective. Our model offers an operational understanding of how a localized detector registers an event from a delocalized quantum field, linking quantum measurement theory with concrete detector models.

•Jan 1, 2025•0 citations

Optical experiments on 3D photonic crystals

A. Femius Koenderink, Willem L. Vos

Photonic crystals are optical materials that have an intricate structure with length scales of the order of the wavelength of light. The flow of photons is controlled in a manner analogous to how electrons propagate through semiconductor crystals, i.e., by Bragg diffraction and the formation of band structures. If the interaction between light and matter is made strong, multiple diffraction and multiple scattering effects dominate. A main research goal is the realization of a "photonic band gap", that is, a frequency range for which no light can propagate in a crystal in any direction, which causes radical modifications of the density of radiative states. Important consequences of photonic band gaps are the complete control over spontaneous and stimulated emission of light, as well as over the propagation of light, in particular photon localization. This opens up the possibility to achieve a "cage for light": trap photons and do with them whatever one chooses. In this talk we will also review means for making such structures, and recent experimental advances in optical experiments.

International Conference on Transparent Optical Networks•Feb 3, 2004•1 citation

Photophysics of Solid State Laser Materials

Yehoshua Y. Kalisky

Light emission occurs as a result of interaction between light and matter. Let us assume a two-level atom with levels 1 (ground state) and 2 (excited state). The energies of the ground and excited states are E 1 and E 2 , respectively, and the energy difference is therefore given by the difference ΔE 12 =E 2 −E 1 . When light with photons of energy equal to this difference is absorbed by the atomic or molecular system, an electron will be excited from level 1 to level 2. The energy of the photons is given by ΔE 12 =E 12 =hν 12 (h is Planck's constant and 1→2 is the frequency of light resulting from the level 1→2 transition). This energy is absorbed by an atom or a molecule that has energy levels, separated by ΔE, where these energy levels are the ground and the excited states. This kind of “quantum jump” of an electron between two states occurs in atomic systems between electronic levels; it can be extended to molecular systems, where vibrational and translational energy levels participate in the quantum jump. The interaction between light and matter involves the transition of electrons between different states. This interaction results in the absorption of photons (stimulated absorption) as well as spontaneous and stimulated emission. These processes can be described using Einstein's A and B coefficients, as will be described in the next paragraphs.

SPIE eBooks•Oct 22, 2009•0 citations

Photon transparency in metallic photonic crystals doped with an ensemble of nanoparticles

Mahi R. Singh

Quantum optics of metallic photonic crystals is studied in this paper. Crystals are made from metallic spheres and a background dielectric material. The refractive index of the metallic spheres depends on the frequencies of the incident light and plasmons whereas the refractive index of the background material is a constant. Crystals are lightly doped with four-level nanoparticles. It is considered that nanoparticles are interacting with the metallic crystals via electron-photon interaction in the dipole approximation. The probe and pump laser fields are applied to monitor the absorption spectrum in the system. Two transparent states are predicted. One is due to the electromagnetically induced transparency and the other is due to the electron-photon interaction. For certain experimental conditions these transparent states merge into one transparent state. The effect of plasmon frequencies has also been studied. It is found that the system can be switched from a transparent state to an absorbing state just by changing the frequency of plasmons. This study can be used to makes new types of optical devices such as switches and optical transistors.

Physical Review A•Jan 28, 2009•30 citations
The absorption of light is one of the most fundamental processes in condensed-matter physics and optics. Here we investigate under which conditions laser light is absorbed by a crystalline material as an electromagnetic wave with delocalized properties or rather as photons that cause discrete, localized, nanometer-sized consequences. We excite the first-order phase transition of vanadium dioxide with laser pulses of sufficient frequency to overcome the band gap but with insufficient pulse energy to overcome the latent heat. According to Maxwell's equations and Bloch theory, no transition should occur, because nowhere in the material is enough energy. Nevertheless, we observe with ultrafast electron diffraction a disordered crystal geometry with nanometer-sized spots of switched material that grow and diminish with time. The amount of localized spots matches approximately to the number of photons in the absorbed laser wave. Two optical experiments substantiate this phenomenon, and simulations reproduce all measurements results. We discuss whether crystals defects, temperature, or a genuine wavefunction collapse can explain the discovered phenomenon. Practically, the reported absorption mechanism enables local consequences at substantially higher energy than average and provides insight into symmetry breaks and non-thermal fluctuations within complex materials.
Under appropriate conditions, absorption of light by a solid can initiate a process by which it is cooled. In particular, energy is extracted from a material when its absorption of a photon is followed by emission of a photon of higher energy. This up-conversion requires some of the solid's electrons to garner energy from atomic vibrations. Here, two schemes for laser cooling via localized electronic states are addressed. The first scheme utilizes the ground state and an excited state of a localized center. In this two-level scheme, the cooling process is initiated with photon absorption in the extreme low-energy tail of a localized state's vibrationally broadened absorption spectrum. The subsequent atomic relaxation transfers energy of especially large vibratory atomic strains into electrical energy that is then extracted via photon emission. The second scheme involves the ground state and two excited states of a localized center. Cooling is facilitated when (i) the photoexcitation of an electron from its ground state to the lower excited level is followed by (ii) electron-phonon-induced promotion to the uppermost level and the subsequent (iii) return of the electron to its ground state with emission of a photon of higher energy than that of the absorbed photon. However, competing relaxation processes contribute to heating. The net cooling power per unit volume is maximized for both schemes, thereby determining characteristics of localized electronic systems that foster optical cooling. The cooling power per unit volume is greatest at high temperatures and falls rapidly as the thermal energy is reduced below each system's luminescence Stokes shift. Moreover, cooling via the three-level scheme is most effective when (i) the energy separation between excited states is smaller than the thermal energy and (ii) the degeneracy of the highest-lying excited state is much larger than that of the center's middle level. These restrictive conditions appear to be satisfied for the three-level systems that to date exhibit laser cooling at or somewhat below room temperature: severely localized crystal-field-split fff-electron states of rare-earth ions.
Interactions between light and molecular matter featuring photon absorption are commonly associated with excitation of individual chromophores. Subsequent relaxation is achieved through numerous mechanisms, such as scattering and energy transfer to neighbouring chromophores. The efficiency of such processes depends on many factors, including the intensity and wavelength of the optical input, the absorption cross-section of the molecule and the relative orientation of molecular components. New photonic materials are developed on the principle that such factors are controllable, duly tailoring the system to suit new technological applications. The parameters that determine the linear response in multicomponent materials are typically assessed within the theoretical framework of classical optics. However, with improved interest and capability in fabricating nanoscale structures (especially those that exhibit quantum effects), it is becoming increasingly relevant to develop theory that more faithfully represents how individual photons engage with matter. In such constructs, the interaction of materials with optical waves and photons is highly dependent on local molecular environment, therefore surrounding structures and ancillary species exert forms of influence on the photophysical processes inherent within dielectric media. At optical wavelengths where the secondary structure displays little intrinsic optical absorption, the role of such components is often interpreted as modifying the input through a corrective local index of refraction. Although expedient in the discussion of bulk properties of a macroscopic medium, it is reasonably supposed at a local chromophore-photon level that optical mechanisms operate in a different fashion. Using a fully quantized approach to the representation of local molecular electronic structure and electrodynamics, this research develops rigorous theory and a corresponding physical interpretation of how photon absorption, scattering and energy transfer are modified by vicinal, non-absorbing chromophores. The results provide insight into the mechanisms achieved within multi-chromophore systems, highlighting factors that assist in the optimization of optical characteristics in designer materials.
Abstract: Starting from the physical intuition that light (massless fields) is delocalized while massive matter is localized, we develop a three-dimensional quantum field theory model to study photon absorption by a material detector. The detector is modeled as a two-level system coupled to a massless scalar field via a linear interaction. We consider three progressively realistic scenarios: (i) a point-like detector absorbing an s-wave spherical photon, (ii) a point-like detector absorbing a plane-wave photon, and (iii) a finite-size detector with a spatial distribution. Using Fermi's golden rule, we compute the transition rates and absorption cross sections. We show that for a point detector, the absorption cross section for s-wave photons is finite and frequency-independent, and for plane-wave photons it is independent of the incident direction. For a finite-size detector, the absorption efficiency is modulated by a form factor that suppresses absorption when the photon wavelength is shorter than the detector size. This provides a quantitative explanation for why microscopic objects (atoms) absorb light efficiently, while macroscopic objects are transparent or reflective. Our model offers an operational understanding of how a localized detector registers an event from a delocalized quantum field, linking quantum measurement theory with concrete detector models.
Photonic crystals are optical materials that have an intricate structure with length scales of the order of the wavelength of light. The flow of photons is controlled in a manner analogous to how electrons propagate through semiconductor crystals, i.e., by Bragg diffraction and the formation of band structures. If the interaction between light and matter is made strong, multiple diffraction and multiple scattering effects dominate. A main research goal is the realization of a "photonic band gap", that is, a frequency range for which no light can propagate in a crystal in any direction, which causes radical modifications of the density of radiative states. Important consequences of photonic band gaps are the complete control over spontaneous and stimulated emission of light, as well as over the propagation of light, in particular photon localization. This opens up the possibility to achieve a "cage for light": trap photons and do with them whatever one chooses. In this talk we will also review means for making such structures, and recent experimental advances in optical experiments.
Light emission occurs as a result of interaction between light and matter. Let us assume a two-level atom with levels 1 (ground state) and 2 (excited state). The energies of the ground and excited states are E 1 and E 2 , respectively, and the energy difference is therefore given by the difference ΔE 12 =E 2 −E 1 . When light with photons of energy equal to this difference is absorbed by the atomic or molecular system, an electron will be excited from level 1 to level 2. The energy of the photons is given by ΔE 12 =E 12 =hν 12 (h is Planck's constant and 1→2 is the frequency of light resulting from the level 1→2 transition). This energy is absorbed by an atom or a molecule that has energy levels, separated by ΔE, where these energy levels are the ground and the excited states. This kind of “quantum jump” of an electron between two states occurs in atomic systems between electronic levels; it can be extended to molecular systems, where vibrational and translational energy levels participate in the quantum jump. The interaction between light and matter involves the transition of electrons between different states. This interaction results in the absorption of photons (stimulated absorption) as well as spontaneous and stimulated emission. These processes can be described using Einstein's A and B coefficients, as will be described in the next paragraphs.
Quantum optics of metallic photonic crystals is studied in this paper. Crystals are made from metallic spheres and a background dielectric material. The refractive index of the metallic spheres depends on the frequencies of the incident light and plasmons whereas the refractive index of the background material is a constant. Crystals are lightly doped with four-level nanoparticles. It is considered that nanoparticles are interacting with the metallic crystals via electron-photon interaction in the dipole approximation. The probe and pump laser fields are applied to monitor the absorption spectrum in the system. Two transparent states are predicted. One is due to the electromagnetically induced transparency and the other is due to the electron-photon interaction. For certain experimental conditions these transparent states merge into one transparent state. The effect of plasmon frequencies has also been studied. It is found that the system can be switched from a transparent state to an absorbing state just by changing the frequency of plasmons. This study can be used to makes new types of optical devices such as switches and optical transistors.