a Quantum Two-Level System with Applications to Photoemission from Metals.

We theoretically study a novel up-converted luminescence from a two-level molecule coupled with an auxiliary system such as an anharmonic LC resonator and a metallic nano-antenna. The auxiliary system is assumed to be strongly driven by a continuous wave laser so that a Mollow triplet appears in the luminescent spectrum. When the peak energy of the upper Mollow triplet sideband is tuned to the molecular excited level, the intensity of the up-converted luminescence is considerably enhanced. At the same time, the population of the two-level molecule is inverted. We also discuss the conditions for high photoemission efficiency in the up-converted luminescence under a highly inverted population. This result indicates the potential applications in future single-molecule lasers.We theoretically study a novel up-converted luminescence from a two-level molecule coupled with an auxiliary system such as an anharmonic LC resonator and a metallic nano-antenna. The auxiliary system is assumed to be strongly driven by a continuous wave laser so that a Mollow triplet appears in the luminescent spectrum. When the peak energy of the upper Mollow triplet sideband is tuned to the molecular excited level, the intensity of the up-converted luminescence is considerably enhanced. At the same time, the population of the two-level molecule is inverted. We also discuss the conditions for high photoemission efficiency in the up-converted luminescence under a highly inverted population. This result indicates the potential applications in future single-molecule lasers.

Journal of the Physical Society of JapanAug 25, 20142 citations

New many-body approach to photoemission and spectral functions

Carl-Olof Almbladh, Claudio Verdozzi

Bulletin of the American Physical SocietyMar 7, 20070 citations

Theory of core-level photoemission and the x-ray edge singularity across the Mott transition

Pablo S. Cornaglia, Antoine Georges

The zero-temperature core-level photoemission spectrum of a Hubbard system is studied across the metal to Mott insulator transition using dynamical mean-field theory and Wilson's numerical renormalization group [Rev. Mod. Phys. 47, 773 (1975)]. An asymmetric power-law divergence is obtained in the metallic phase with an exponent $\ensuremath{\alpha}(U,Q)\ensuremath{-}1$, which depends on the strength of both the Hubbard interaction $U$ and the core-hole potential $Q$ . For $Q\ensuremath{\lesssim}{U}_{c}∕2$, $\ensuremath{\alpha}$ decreases with increasing $U$ and vanishes at the transition $(U\ensuremath{\rightarrow}{U}_{c})$ leading to a symmetric peak in the insulating phase. For $Q\ensuremath{\gtrsim}{U}_{c}∕2$, $\ensuremath{\alpha}$ remains finite, close to the transition, but the integrated intensity of the power law vanishes and there is no associated peak in the insulator. The weight and position of the remaining peaks in the spectra can be understood within a molecular orbital approach.The zero-temperature core-level photoemission spectrum of a Hubbard system is studied across the metal to Mott insulator transition using dynamical mean-field theory and Wilson's numerical renormalization group [Rev. Mod. Phys. 47, 773 (1975)]. An asymmetric power-law divergence is obtained in the metallic phase with an exponent $\ensuremath{\alpha}(U,Q)\ensuremath{-}1$, which depends on the strength of both the Hubbard interaction $U$ and the core-hole potential $Q$. For $Q\ensuremath{\lesssim}{U}_{c}∕2$, $\ensuremath{\alpha}$ decreases with increasing $U$ and vanishes at the transition $(U\ensuremath{\rightarrow}{U}_{c})$ leading to a symmetric peak in the insulating phase. For $Q\ensuremath{\gtrsim}{U}_{c}∕2$, $\ensuremath{\alpha}$ remains finite, close to the transition, but the integrated intensity of the power law vanishes and there is no associated peak in the insulator. The weight and position of the remaining peaks in the spectra can be understood within a molecular orbital approach.

arXiv:cond-mat/0607693Physical Review BMar 12, 200729 citations

Tracking adiabaticity in nonequilibrium many-body systems using x-ray photoemission from metals as a stringent test

Gustavo Diniz, Felipe D. Picoli, L. Nunes de Oliveira +1 more

The level of adiabaticity determines many properties of time-dependent quantum systems. However, a reliable and easy-to-apply criterion to check and track it remains an open question, especially for complex many-body systems. Here we test techniques based on metrics which have been recently proposed to quantitatively characterize and track adiabaticity. We investigate the time evolution of x-ray photoemission in metals, which displays a strongly out-of-equilibrium character, continuum energy spectrum, and experiences the Anderson orthogonality catastrophe: a nightmarish scenario for this type of test. Our results show that the metrics-based methods remains valid. In particular, we demonstrate that the natural local density distance is able not only to track adiabaticity, but also to provide information not captured by the corresponding Bures' or trace distances about the system's dynamics. In the process, we establish an explicit upper limit for this local density distance in terms of the trace distance, and derive a simple analytical solution that accurately describes the time evolution of a Fermi gas with a localized scattering potential for a large range of parameters. We also demonstrate that, for x-ray photoemission, the quantum adiabatic criterion, as commonly used, fails to predict and track adiabaticity. The local particle density is typically much simpler to compute than the corresponding quantum state and it is experimentally measurable: this makes the method tested extremely appealing.The level of adiabaticity determines many properties of time-dependent quantum systems. However, a reliable and easy-to-apply criterion to check and track it remains an open question, especially for complex many-body systems. Here we test techniques based on metrics which have been recently proposed to quantitatively characterize and track adiabaticity. We investigate the time evolution of x-ray photoemission in metals, which displays a strongly out-of-equilibrium character, continuum energy spectrum, and experiences the Anderson orthogonality catastrophe: a nightmarish scenario for this type of test. Our results show that the metrics-based methods remains valid. In particular, we demonstrate that the natural local density distance is able not only to track adiabaticity, but also to provide information not captured by the corresponding Bures' or trace distances about the system's dynamics. In the process, we establish an explicit upper limit for this local density distance in terms of the trace distance, and derive a simple analytical solution that accurately describes the time evolution of a Fermi gas with a localized scattering potential for a large range of parameters. We also demonstrate that, for x-ray photoemission, the quantum adiabatic criterion, as commonly used, fails to predict and track adiabaticity. The local particle density is typically much simpler to compute than the corresponding quantum state and it is experimentally measurable: this makes the method tested extremely appealing.

arXiv:2502.11313Physical Review AJan 9, 20261 citation

U

and the core-hole potential

Q

. For $Q\ensuremath{\lesssim}{U}_{c}∕2$, $\ensuremath{\alpha}$ decreases with increasing

U

and vanishes at the transition $(U\ensuremath{\rightarrow}{U}_{c})$ leading to a symmetric peak in the insulating phase. For $Q\ensuremath{\gtrsim}{U}_{c}∕2$, $\ensuremath{\alpha}$ remains finite, close to the transition, but the integrated intensity of the power law vanishes and there is no associated peak in the insulator. The weight and position of the remaining peaks in the spectra can be understood within a molecular orbital approach.