Pub Date : 2024-07-02DOI: 10.1209/0295-5075/ad5e1c
Sudip Mandal, R. S. Grewal, Swarupananda Pradhan
The atomic population trapped in irrelevant atomic states is a limiting factor for sensors based on laser-atom interaction. Using a bi-chromatic light field along with a specific combination of magnetic fields, we show a significant increase in the amplitude (i.e., more than seven times) of a two-photon coherent population trapping (CPT) resonance, which can be effectively used for atomic magnetometry. This increase in amplitude can be explained through enhanced optical pumping via the transfer of population to the relevant Zeeman states. Our experimental observations are consistent with the theoretical calculations carried out for a realistic three-level atomic system using density matrix formalism. We further discuss the optimum condition for enhanced optical pumping by adjusting the ground-state decoherence rate. Enhanced optical pumping through the manipulation of the magnetic field is quite important and is of great interest in the field of quantum technology.
{"title":"Enhanced optical pumping using mutually orthogonal magnetic fields for quantum sensing","authors":"Sudip Mandal, R. S. Grewal, Swarupananda Pradhan","doi":"10.1209/0295-5075/ad5e1c","DOIUrl":"https://doi.org/10.1209/0295-5075/ad5e1c","url":null,"abstract":"\u0000 The atomic population trapped in irrelevant atomic states is a limiting factor for sensors based on laser-atom interaction. Using a bi-chromatic light field along with a specific combination of magnetic fields, we show a significant increase in the amplitude (i.e., more than seven times) of a two-photon coherent population trapping (CPT) resonance, which can be effectively used for atomic magnetometry. This increase in amplitude can be explained through enhanced optical pumping via the transfer of population to the relevant Zeeman states. Our experimental observations are consistent with the theoretical calculations carried out for a realistic three-level atomic system using density matrix formalism. We further discuss the optimum condition for enhanced optical pumping by adjusting the ground-state decoherence rate. Enhanced optical pumping through the manipulation of the magnetic field is quite important and is of great interest in the field of quantum technology.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"11 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141684215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1209/0295-5075/ad5d87
Martial Morisse, Stuti Joshi, J. Mika, J. Capella, Robin Kaiser, Romain Bachelard, Lukas Slodicka, M. Hugbart
Light is characterized by its electric field, yet quantum optics has revealed the importance of monitoring photon-photon correlations at all orders. We here present a comparative study of two experimental setups, composed of cold and warm Rubidium atoms, respectively, which allow us to probe and compare photon correlations. The former operates in the quantum regime where spontaneous emission dominates, whereas the latter exhibits a temperature-limited coherence time. We demonstrate our capability to measure photon correlations up to the fourth order which could be useful to better characterize light scattered by cold atoms beyond the chaotic statistics.
{"title":"Temporal coherences of atomic chaotic light sources: The Siegert relation and its generalisation to higher order correlation functions","authors":"Martial Morisse, Stuti Joshi, J. Mika, J. Capella, Robin Kaiser, Romain Bachelard, Lukas Slodicka, M. Hugbart","doi":"10.1209/0295-5075/ad5d87","DOIUrl":"https://doi.org/10.1209/0295-5075/ad5d87","url":null,"abstract":"\u0000 Light is characterized by its electric field, yet quantum optics has revealed the importance of monitoring photon-photon correlations at all orders. We here present a comparative study of two experimental setups, composed of cold and warm Rubidium atoms, respectively, which allow us to probe and compare photon correlations. The former operates in the quantum regime where spontaneous emission dominates, whereas the latter exhibits a temperature-limited coherence time. We demonstrate our capability to measure photon correlations up to the fourth order which could be useful to better characterize light scattered by cold atoms beyond the chaotic statistics.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"94 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141697503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a method is theoretically proposed to obtain a novel movable second-order Helmholtz resonator by adding a perforated plate inside the cavity of the Helmholtz resonator that can be freely tuned up and down. Through software simulation, it is concluded that the resonator meets the design objective of saving production costs that when the manufactured physical object is required to change the structural parameters, it only needs to be dynamically adjusted on this basis, rather than needing to reproduce a new physical object with new structural parameters. Meanwhile, it has excellent acoustic characteristics, with a stop band in the range of 80-610Hz at the low frequency and a bandpass acoustic focusing characteristic in the range of 4050-5250Hz. It can achieve directional adjustable focus acoustic focusing for plane waves incident at any angle, and directional adjustable focus acoustic focusing for cylindrical wave incidence, with excellent focusing effect. The added perforated plate changes the resonator one-item structure model and can be reused to meet different structural parameters.
{"title":"Broadband characteristics and bandpass acoustic focusing via movable second-order Helmoltz resonator","authors":"Mengchun Yang, Jinyu Zhao, Zihao Liu, Shulei Gong, Yuan Liu, Yongchang Li","doi":"10.1209/0295-5075/ad56c4","DOIUrl":"https://doi.org/10.1209/0295-5075/ad56c4","url":null,"abstract":"\u0000 In this paper, a method is theoretically proposed to obtain a novel movable second-order Helmholtz resonator by adding a perforated plate inside the cavity of the Helmholtz resonator that can be freely tuned up and down. Through software simulation, it is concluded that the resonator meets the design objective of saving production costs that when the manufactured physical object is required to change the structural parameters, it only needs to be dynamically adjusted on this basis, rather than needing to reproduce a new physical object with new structural parameters. Meanwhile, it has excellent acoustic characteristics, with a stop band in the range of 80-610Hz at the low frequency and a bandpass acoustic focusing characteristic in the range of 4050-5250Hz. It can achieve directional adjustable focus acoustic focusing for plane waves incident at any angle, and directional adjustable focus acoustic focusing for cylindrical wave incidence, with excellent focusing effect. The added perforated plate changes the resonator one-item structure model and can be reused to meet different structural parameters.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"42 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.1209/0295-5075/ad56c3
A. Kolovsky
We revisit the problem of two-terminal transport of non-interacting Fermi particles in a mesoscopic device. First, we generalize the transport problem by including into consideration relaxation processes in contacts (which are characterized by the contact self-thermalization rate $gamma$) and then solve it by using the master equation approach. In the limit $gammarightarrow0$ the obtained results are shown to reproduce those of the Landauer theory. Thus, the presented analysis proves correspondence between the Landauer and master-equation approaches to quantum transport, -- the problem which waited its solution for decades
{"title":"Deriving Landauer's result by using the master equation approach","authors":"A. Kolovsky","doi":"10.1209/0295-5075/ad56c3","DOIUrl":"https://doi.org/10.1209/0295-5075/ad56c3","url":null,"abstract":"\u0000 We revisit the problem of two-terminal transport of non-interacting Fermi particles in a mesoscopic device. First, we generalize the transport problem by including into consideration relaxation processes in contacts (which are characterized by the contact self-thermalization rate $gamma$) and then solve it by using the master equation approach. In the limit $gammarightarrow0$ the obtained results are shown to reproduce those of the Landauer theory. Thus, the presented analysis proves correspondence between the Landauer and master-equation approaches to quantum transport, -- the problem which waited its solution for decades","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"16 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141356373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.1209/0295-5075/ad56c2
Abhay Srivastav, Vivek Pandey, A. Pati
Given the initial and final states of a quantum system, the speed of transportation of state vector in the projective Hilbert space governs the quantum speed limit. Here, we ask the question what happens to the quantum speed limit under continuous measurement process. We model the continuous measurement process by a non-Hermitian Hamiltonian which keeps the evolution of the system Schr{"o}dinger-like even under the process of measurement. Using this specific measurement model, we prove that under continuous measurement, the speed of transportation of a quantum system tends to zero. Interestingly, we also find that for small time scale, there is an enhancement of quantum speed even if the measurement strength is finite. Our findings can have applications in quantum computing and quantum control where dynamics is governed by both unitary and measurement processes.
{"title":"Effect of measurements on quantum speed limit","authors":"Abhay Srivastav, Vivek Pandey, A. Pati","doi":"10.1209/0295-5075/ad56c2","DOIUrl":"https://doi.org/10.1209/0295-5075/ad56c2","url":null,"abstract":"\u0000 Given the initial and final states of a quantum system, the speed of transportation of state vector in the projective Hilbert space governs the quantum speed limit. Here, we ask the question what happens to the quantum speed limit under continuous measurement process. We model the continuous measurement process by a non-Hermitian Hamiltonian which keeps the evolution of the system Schr{\"o}dinger-like even under the process of measurement. Using this specific measurement model, we prove that under continuous measurement, the speed of transportation of a quantum system tends to zero. Interestingly, we also find that for small time scale, there is an enhancement of quantum speed even if the measurement strength is finite. Our findings can have applications in quantum computing and quantum control where dynamics is governed by both unitary and measurement processes.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"63 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141360127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-06DOI: 10.1209/0295-5075/ad54ec
Oleg K. Cheremnykh, V. Lashkin
We present an exact solution to the problem of a self-consistent equilibrium force-free magnetic flux rope. Unlike other approaches, we use magnetostatic equations and assume only a relatively rapid decrease in the axial magnetic field at infinity. For the first time we obtain a new nonlinear equation for the axial current density, the derivation of which does not require any phenomenological assumptions. From the resulting nonlinear equation, we analytically find the radial profiles of the components of the magnetic field strength and current density.
{"title":"Self-consistent equilibrium of a force-free magnetic flux rope","authors":"Oleg K. Cheremnykh, V. Lashkin","doi":"10.1209/0295-5075/ad54ec","DOIUrl":"https://doi.org/10.1209/0295-5075/ad54ec","url":null,"abstract":"\u0000 We present an exact solution to the problem of a self-consistent equilibrium force-free magnetic flux rope. Unlike other approaches, we use magnetostatic equations and assume only a relatively rapid decrease in the axial magnetic field at infinity. For the first time we obtain a new nonlinear equation for the axial current density, the derivation of which does not require any phenomenological assumptions. From the resulting nonlinear equation, we analytically find the radial profiles of the components of the magnetic field strength and current density.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"106 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141377859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1209/0295-5075/ad5469
M. Georgiev
An exact classical approach to the calculation of electron's self-energy and anomalous g-factor is reported. The electron's intrinsic dynamics, related electrodynamics and occurrence of anomalous magnetic moment are completely determined. A unique regularization of the electromagnetic field scalar potential underlying all results is derived. Fundamental transcendental equation satisfied by the electron's anomalous g-factor is obtained, with solution a_e=0.0011596521800027(65), matching the experimentally measured value reported in the literature to 0.59 parts per trillion. Field representation of the electron intrinsic and orbital dynamics in atoms is discussed.
报告采用精确的经典方法计算了电子的自能和反常 g 因子。电子的本征动力学、相关电动力学和反常磁矩的发生都已完全确定。推导出了作为所有结果基础的电磁场标量势的独特正则化。得到了满足电子反常 g 因子的基本超越方程，解 a_e=0.0011596521800027(65)，与文献报道的实验测量值万亿分之 0.59 相符。讨论了原子中电子本征和轨道动力学的场表示。
{"title":"Exact classical approach to the electron's self-energy and anomalous g-factor","authors":"M. Georgiev","doi":"10.1209/0295-5075/ad5469","DOIUrl":"https://doi.org/10.1209/0295-5075/ad5469","url":null,"abstract":"\u0000 An exact classical approach to the calculation of electron's self-energy and anomalous g-factor is reported. The electron's intrinsic dynamics, related electrodynamics and occurrence of anomalous magnetic moment are completely determined. A unique regularization of the electromagnetic field scalar potential underlying all results is derived. Fundamental transcendental equation satisfied by the electron's anomalous g-factor is obtained, with solution a_e=0.0011596521800027(65), matching the experimentally measured value reported in the literature to 0.59 parts per trillion. Field representation of the electron intrinsic and orbital dynamics in atoms is discussed.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"84 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-03DOI: 10.1209/0295-5075/ad5374
Léonie Dagoudo, F. A. Dossa, G. Y. Avossevou
We study the quantum characteristics of the Dirac oscillator within the framework of Heisenberg's generalized uncertainty principle. This principle leads to the appearance of a minimal length of the order of the Planck length. Hidden symmetries are identified to solve the model algebraically. The presence of the minimal length leads to a quadratic dependence of the energy spectrum on the quantum number $n$, implying the hard confinement property of the system. Thermodynamic properties are calculated using the canonical partition function. The latter is well determined by the method based on Epstein's zeta function. The results reveal that the minimal length has a significant effect on the thermodynamic properties.
{"title":"Algebraic solution and thermodynamic properties for the one- and two-dimensional Dirac oscillator with minimal length uncertainty relations","authors":"Léonie Dagoudo, F. A. Dossa, G. Y. Avossevou","doi":"10.1209/0295-5075/ad5374","DOIUrl":"https://doi.org/10.1209/0295-5075/ad5374","url":null,"abstract":"\u0000 We study the quantum characteristics of the Dirac oscillator within the framework of Heisenberg's generalized uncertainty principle. This principle leads to the appearance of a minimal length of the order of the Planck length. Hidden symmetries are identified to solve the model algebraically. The presence of the minimal length leads to a quadratic dependence of the energy spectrum on the quantum number $n$, implying the hard confinement property of the system. Thermodynamic properties are calculated using the canonical partition function. The latter is well determined by the method based on Epstein's zeta function. The results reveal that the minimal length has a significant effect on the thermodynamic properties.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"5 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141269397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-23DOI: 10.1209/0295-5075/ad4fbb
G. L. Klimchitskaya, Alexander S. Korotkov, Vera V. Loboda, V. Mostepanenko
The Casimir force caused by the electromagnetic fluctuations is computed in the configurations of micro- and nanoelectromechanical pressure sensors using Si membranes and either Si or Au-coated Si substrates. It is shown that if, under the influence of external pressure, the membrane-substrate separation drops to below 100 nm, the Casimir force makes a profound effect on the sensor functioning. There exists the maximum value of external pressure depending on the sensor parameters such that it finds itself in a state of unstable equilibrium. For this and larger pressures, the Casimir force leads to a collapse of the sensor, which loses its functionality. For any smaller external pressures, there exist two equilibrium positions, one of which is unstable and another one is stable, at smaller and larger membrane-substrate separations, respectively. The latter can be safely used for the pressure measurements. Possible applications of the ontained results in the design of micro and nano pressure sensors of next generations with further decreased dimensions are discussed.
{"title":"Role of the Casimir force in micro- and nanoelectromechanical pressure sensors","authors":"G. L. Klimchitskaya, Alexander S. Korotkov, Vera V. Loboda, V. Mostepanenko","doi":"10.1209/0295-5075/ad4fbb","DOIUrl":"https://doi.org/10.1209/0295-5075/ad4fbb","url":null,"abstract":"\u0000 The Casimir force caused by the electromagnetic fluctuations is computed in the configurations of micro- and nanoelectromechanical pressure sensors using Si membranes and either Si or Au-coated Si substrates. It is shown that if, under the influence of external pressure, the membrane-substrate separation drops to below 100 nm, the Casimir force makes a profound effect on the sensor functioning. There exists the maximum value of external pressure depending on the sensor parameters such that it finds itself in a state of unstable equilibrium. For this and larger pressures, the Casimir force leads to a collapse of the sensor, which loses its functionality. For any smaller external pressures, there exist two equilibrium positions, one of which is unstable and another one is stable, at smaller and larger membrane-substrate separations, respectively. The latter can be safely used for the pressure measurements. Possible applications of the ontained results in the design of micro and nano pressure sensors of next generations with further decreased dimensions are discussed.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"58 48","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141102592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-22DOI: 10.1209/0295-5075/ad4f0f
Charli Chinmayee Pal, Prasanta Kumar Mahapatra
A solid-state experiment based on quantum tunneling is proposed to reproduce the natural numbers and prime numbers as resonant tunneling energies in a double barrier system (DBS). For getting the prime numbers as eigenvalues the well potential is considered as the superposition of a smooth potential which is estimated using semi-classical approach and a weak local fluctuating potential. We use the transfer matrix approach and finite element method by taking only the smooth part of the potential to obtain resonant energies which reproduces the local average prime density and the local average prime gap exactly. The methodology when applied to a quadratic potential of the well, produces whole numbers as eigenvalues except for a constant zero-point energy-the energy levels of a simple harmonic oscillator.
{"title":"Exact prime density reproduced through resonant tunneling across a doublebarrier system","authors":"Charli Chinmayee Pal, Prasanta Kumar Mahapatra","doi":"10.1209/0295-5075/ad4f0f","DOIUrl":"https://doi.org/10.1209/0295-5075/ad4f0f","url":null,"abstract":"\u0000 A solid-state experiment based on quantum tunneling is proposed to reproduce the natural numbers and prime numbers as resonant tunneling energies in a double barrier system (DBS). For getting the prime numbers as eigenvalues the well potential is considered as the superposition of a smooth potential which is estimated using semi-classical approach and a weak local fluctuating potential. We use the transfer matrix approach and finite element method by taking only the smooth part of the potential to obtain resonant energies which reproduces the local average prime density and the local average prime gap exactly. The methodology when applied to a quadratic potential of the well, produces whole numbers as eigenvalues except for a constant zero-point energy-the energy levels of a simple harmonic oscillator.","PeriodicalId":503117,"journal":{"name":"Europhysics Letters","volume":"52 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141108642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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