Entanglement and quantum correlations between atoms are not usually considered key ingredients of the superradiant phase transition.Here we consider the Tavis–Cummings model,a solvable system of two-levels atoms,coup...Entanglement and quantum correlations between atoms are not usually considered key ingredients of the superradiant phase transition.Here we consider the Tavis–Cummings model,a solvable system of two-levels atoms,coupled with a single-mode quantized electromagnetic field.This system undergoes a superradiant phase transition,even in a finite-size framework,accompanied by a spontaneous symmetry breaking,and an infinite sequence of energy level crossings.We find approximated expressions for the ground state,its energy,and the position of the level crossings,valid in the limit of a very large number of photons with respect to that of the atoms.In that same limit,we find that the number of photons scales quadratically with the coupling strength,and linearly with the system size,providing a new insight into the superradiance phenomenon.Resorting to novel multipartite measures,we then demonstrate that this quantum phase transition is accompanied by a crossover in the quantum correlations and entanglement between the atoms(qubits).The latters therefore represent suited order parameters for this transition.Finally,we show that these properties of the quantum phase transition persist in the thermodynamic limit.展开更多
In the present paper we address the general problem of selective electrodynamic interactions between DNA and protein,which is motivated by decades of theoretical study and our very recent experimental findings providi...In the present paper we address the general problem of selective electrodynamic interactions between DNA and protein,which is motivated by decades of theoretical study and our very recent experimental findings providing a first evidence for their activation.Inspired by the Davydov and Holstein-Fröhlich models describing electron motion along biomolecules,and using a model Hamiltonian written in second quantization,the timedependent variational principle is used to derive the dynamical equations of the system.We demonstrate the efficacy of this second-quantized model for a well-documented biochemical system consisting of a restriction enzyme,EcoRI,which binds selectively to a palindromic six-base-pair target within a DNA oligonucleotide sequence to catalyze a DNA doublestrand cleavage.The time-domain Fourier spectra of the electron currents numerically computed for the DNA fragment and for the EcoRI enzyme,respectively,exhibit a cross-correlation spectrum with a sharp co-resonance peak.When the target DNA recognition sequence is randomized,this sharp co-resonance peak is replaced with a broad and noisy spectrum.Such a sequence-dependent charge transfer phenomenology is suggestive of a potentially rich variety of selective electrodynamic interactions influencing the coordinated activity of DNA substrates,enzymes,transcription factors,ligands,and other proteins under realistic biochemical conditions characterized by electron-phonon excitations.展开更多
We show that the manifold of quantum states is endowed with a rich and nontrivial geometric structure.We derive the Fubini−Study metric of the projective Hilbert space of a multi-qubit quantum system,endowing it with ...We show that the manifold of quantum states is endowed with a rich and nontrivial geometric structure.We derive the Fubini−Study metric of the projective Hilbert space of a multi-qubit quantum system,endowing it with a Riemannian metric structure,and investigate its deep link with the entanglement of the states of this space.As a measure,we adopt the entanglement distance E preliminary proposed in Phys.Rev.A 101,042129(2020).Our analysis shows that entanglement has a geometric interpretation:E(|ψ>)is the minimum value of the sum of the squared distances between|ψ>and its conjugate states,namely the statesυ^(μ).σ^(μ)|ψ>,whereυ^(μ)are unit vectors andμruns on the number of parties.Within the proposed geometric approach,we derive a general method to determine when two states are not the same state up to the action of local unitary operators.Furthermore,we prove that the entanglement distance,along with its convex roof expansion to mixed states,fulfils the three conditions required for an entanglement measure,that is:i)E(|ψ>)=0 iff|ψ>is fully separable;ii)E is invariant under local unitary transformations;iii)E does not increase under local operation and classical communications.Two different proofs are provided for this latter property.We also show that in the case of two qubits pure states,the entanglement distance for a state|ψ>coincides with two times the square of the concurrence of this state.We propose a generalization of the entanglement distance to continuous variable systems.Finally,we apply the proposed geometric approach to the study of the entanglement magnitude and the equivalence classes properties,of three families of states linked to the Greenberger−Horne−Zeilinger states,the Briegel Raussendorf states and the W states.As an example of application for the case of a system with continuous variables,we have considered a system of two coupled Glauber coherent states.展开更多
Background Plankton is the essential ecological category that occupies the lower levels of aquatic trophic networks,representing a good indicator of environmental change.However,most studies deal with distribution of ...Background Plankton is the essential ecological category that occupies the lower levels of aquatic trophic networks,representing a good indicator of environmental change.However,most studies deal with distribution of single species or taxa and do not take into account the complex of biological interactions of the real world that rule the ecological processes.Results This study focused on analyzing Antarctic marine phytoplankton,mesozooplankton,and microzooplankton,examining their biological interactions and co-existences.Field data yielded 1053 biological interaction values,762 coexistence values,and 15 zero values.Six phytoplankton assemblages and six copepod species were selected based on their abundance and ecological roles.Using 23 environmental descriptors,we modelled the distribution of taxa to accurately represent their occurrences.Sampling was conducted during the 2016–2017 Italian National Antarctic Programme(PNRA)‘P-ROSE’project in the East Ross Sea.Machine learning techniques were applied to the occurrence data to generate 48 predictive species distribution maps(SDMs),producing 3D maps for the entire Ross Sea area.These models quantitatively predicted the occurrences of each copepod and phytoplankton assemblage,providing crucial insights into potential variations in biotic and trophic interactions,with signifcant implications for the management and conservation of Antarctic marine resources.The Receiver Operating Characteristic(ROC)results indicated the highest model efciency,for Cyanophyta(74%)among phytoplankton assemblages and Paralabidocera antarctica(83%)among copepod communities.The SDMs revealed distinct spatial heterogeneity in the Ross Sea area,with an average Relative Index of Occurrence values of 0.28(min:0;max:0.65)for phytoplankton assemblages and 0.39(min:0;max:0.71)for copepods.Conclusion The results of this study are essential for a science-based management for one of the world’s most pristine ecosystems and addressing potential climate-induced alterations in species interactions.Our study emphasizes the importance of considering biological interactions in planktonic studies,employing open access and machine learning for measurable and repeatable distribution modelling,and providing crucial ecological insights for informed conservation strategies in the face of environmental change.展开更多
基金the RESEARCH SUPPORT PLAN 2022-Call for applications for funding allocation to research projects curiosity driven(F CUR)-Project“Entanglement Protection of Qubits’Dynamics in a Cavity”-EPQDC and the support by the Italian National Group of Mathematical Physics(GNFM-INdAM)INFN Pisa for the financial support to this activity.
文摘Entanglement and quantum correlations between atoms are not usually considered key ingredients of the superradiant phase transition.Here we consider the Tavis–Cummings model,a solvable system of two-levels atoms,coupled with a single-mode quantized electromagnetic field.This system undergoes a superradiant phase transition,even in a finite-size framework,accompanied by a spontaneous symmetry breaking,and an infinite sequence of energy level crossings.We find approximated expressions for the ground state,its energy,and the position of the level crossings,valid in the limit of a very large number of photons with respect to that of the atoms.In that same limit,we find that the number of photons scales quadratically with the coupling strength,and linearly with the system size,providing a new insight into the superradiance phenomenon.Resorting to novel multipartite measures,we then demonstrate that this quantum phase transition is accompanied by a crossover in the quantum correlations and entanglement between the atoms(qubits).The latters therefore represent suited order parameters for this transition.Finally,we show that these properties of the quantum phase transition persist in the thermodynamic limit.
文摘In the present paper we address the general problem of selective electrodynamic interactions between DNA and protein,which is motivated by decades of theoretical study and our very recent experimental findings providing a first evidence for their activation.Inspired by the Davydov and Holstein-Fröhlich models describing electron motion along biomolecules,and using a model Hamiltonian written in second quantization,the timedependent variational principle is used to derive the dynamical equations of the system.We demonstrate the efficacy of this second-quantized model for a well-documented biochemical system consisting of a restriction enzyme,EcoRI,which binds selectively to a palindromic six-base-pair target within a DNA oligonucleotide sequence to catalyze a DNA doublestrand cleavage.The time-domain Fourier spectra of the electron currents numerically computed for the DNA fragment and for the EcoRI enzyme,respectively,exhibit a cross-correlation spectrum with a sharp co-resonance peak.When the target DNA recognition sequence is randomized,this sharp co-resonance peak is replaced with a broad and noisy spectrum.Such a sequence-dependent charge transfer phenomenology is suggestive of a potentially rich variety of selective electrodynamic interactions influencing the coordinated activity of DNA substrates,enzymes,transcription factors,ligands,and other proteins under realistic biochemical conditions characterized by electron-phonon excitations.
基金support from the Research Support Plan 2022-Call for applications for funding allocation to research projects curiosity driven(F CUR)-Project“Entanglement Protection of Qubits’Dynamics in a Cavity”-EPQDCthe support by the Italian National Group of Mathematical Physics(GNFM-INdAM)financial support to this activity.
文摘We show that the manifold of quantum states is endowed with a rich and nontrivial geometric structure.We derive the Fubini−Study metric of the projective Hilbert space of a multi-qubit quantum system,endowing it with a Riemannian metric structure,and investigate its deep link with the entanglement of the states of this space.As a measure,we adopt the entanglement distance E preliminary proposed in Phys.Rev.A 101,042129(2020).Our analysis shows that entanglement has a geometric interpretation:E(|ψ>)is the minimum value of the sum of the squared distances between|ψ>and its conjugate states,namely the statesυ^(μ).σ^(μ)|ψ>,whereυ^(μ)are unit vectors andμruns on the number of parties.Within the proposed geometric approach,we derive a general method to determine when two states are not the same state up to the action of local unitary operators.Furthermore,we prove that the entanglement distance,along with its convex roof expansion to mixed states,fulfils the three conditions required for an entanglement measure,that is:i)E(|ψ>)=0 iff|ψ>is fully separable;ii)E is invariant under local unitary transformations;iii)E does not increase under local operation and classical communications.Two different proofs are provided for this latter property.We also show that in the case of two qubits pure states,the entanglement distance for a state|ψ>coincides with two times the square of the concurrence of this state.We propose a generalization of the entanglement distance to continuous variable systems.Finally,we apply the proposed geometric approach to the study of the entanglement magnitude and the equivalence classes properties,of three families of states linked to the Greenberger−Horne−Zeilinger states,the Briegel Raussendorf states and the W states.As an example of application for the case of a system with continuous variables,we have considered a system of two coupled Glauber coherent states.
文摘Background Plankton is the essential ecological category that occupies the lower levels of aquatic trophic networks,representing a good indicator of environmental change.However,most studies deal with distribution of single species or taxa and do not take into account the complex of biological interactions of the real world that rule the ecological processes.Results This study focused on analyzing Antarctic marine phytoplankton,mesozooplankton,and microzooplankton,examining their biological interactions and co-existences.Field data yielded 1053 biological interaction values,762 coexistence values,and 15 zero values.Six phytoplankton assemblages and six copepod species were selected based on their abundance and ecological roles.Using 23 environmental descriptors,we modelled the distribution of taxa to accurately represent their occurrences.Sampling was conducted during the 2016–2017 Italian National Antarctic Programme(PNRA)‘P-ROSE’project in the East Ross Sea.Machine learning techniques were applied to the occurrence data to generate 48 predictive species distribution maps(SDMs),producing 3D maps for the entire Ross Sea area.These models quantitatively predicted the occurrences of each copepod and phytoplankton assemblage,providing crucial insights into potential variations in biotic and trophic interactions,with signifcant implications for the management and conservation of Antarctic marine resources.The Receiver Operating Characteristic(ROC)results indicated the highest model efciency,for Cyanophyta(74%)among phytoplankton assemblages and Paralabidocera antarctica(83%)among copepod communities.The SDMs revealed distinct spatial heterogeneity in the Ross Sea area,with an average Relative Index of Occurrence values of 0.28(min:0;max:0.65)for phytoplankton assemblages and 0.39(min:0;max:0.71)for copepods.Conclusion The results of this study are essential for a science-based management for one of the world’s most pristine ecosystems and addressing potential climate-induced alterations in species interactions.Our study emphasizes the importance of considering biological interactions in planktonic studies,employing open access and machine learning for measurable and repeatable distribution modelling,and providing crucial ecological insights for informed conservation strategies in the face of environmental change.
