Pub Date : 2024-08-07DOI: 10.1088/1367-2630/ad69b9
Gao-Feng Jiao
The topology of feedback optical parametric amplifier (FOPA) renders a number of significant advantages over the topology of traditional optical parametric amplifier (TOPA) such as a higher degree of quantum correlation, all-phase entanglement enhancement, and the robustness of the losses. Here, we propose a feedback-assisted interferometer based on the topology of FOPA for quantum metrology. We theoretically study the phase sensitivity with the method of homodyne detection and product detection. By manipulating the feedback strength of the FOPA, the phase sensitivity can be further enhanced, and approach the quantum Cramér-Rao bound. Furthermore, we demonstrate that our proposal is superior to the SU(1,1) interferometer based on the topology of TOPA.
反馈光参量放大器（FOPA）拓扑结构与传统光参量放大器（TOPA）拓扑结构相比具有许多显著优势，如量子关联度更高、全相纠缠增强和损耗鲁棒性强等。在此，我们提出了一种基于 FOPA 拓扑的反馈辅助干涉仪，用于量子计量。我们用同调检测和乘积检测的方法从理论上研究了相位灵敏度。通过调节 FOPA 的反馈强度，相位灵敏度可以进一步提高，并接近量子克拉梅尔-拉奥约束。此外，我们还证明了我们的方案优于基于 TOPA 拓扑的 SU(1,1) 干涉仪。
{"title":"Enhanced phase sensitivity in a feedback-assisted interferometer","authors":"Gao-Feng Jiao","doi":"10.1088/1367-2630/ad69b9","DOIUrl":"https://doi.org/10.1088/1367-2630/ad69b9","url":null,"abstract":"The topology of feedback optical parametric amplifier (FOPA) renders a number of significant advantages over the topology of traditional optical parametric amplifier (TOPA) such as a higher degree of quantum correlation, all-phase entanglement enhancement, and the robustness of the losses. Here, we propose a feedback-assisted interferometer based on the topology of FOPA for quantum metrology. We theoretically study the phase sensitivity with the method of homodyne detection and product detection. By manipulating the feedback strength of the FOPA, the phase sensitivity can be further enhanced, and approach the quantum Cramér-Rao bound. Furthermore, we demonstrate that our proposal is superior to the SU(1,1) interferometer based on the topology of TOPA.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1088/1367-2630/ad67fe
Meghdad Saeedian, Chengyi Tu, Fabio Menegazzo, Paolo D’Odorico, Sandro Azaele and Samir Suweis
Games with environmental feedback have become a crucial area of study across various scientific domains, modelling the dynamic interplay between human decisions and environmental changes, and highlighting the consequences of our choices on natural resources and biodiversity. In this work, we propose a co-evolutionary model for human-environment systems that incorporates the effects of knowledge feedback and social interaction on the sustainability of common pool resources (CPRs). The model represents consumers as agents who adjust their resource extraction based on the resource’s state. These agents are connected through social networks, where links symbolize either affinity or aversion among them. The interplay between social dynamics and resource dynamics is explored, with the system’s evolution analyzed across various network topologies and initial conditions. We find that knowledge feedback can independently sustain CPRs. However, the impact of social interactions on sustainability is dual-faceted: it can either support or impede sustainability, influenced by the network’s connectivity and heterogeneity. A notable finding is the identification of a critical network mean degree, beyond which a depletion/repletion transition parallels an absorbing/active state transition in social dynamics, i.e. individual agents and their connections are/are not prone to being frozen in their social states. Furthermore, the study examines the evolution of the social network, revealing the emergence of two polarized groups where agents within each community have the same affinity. Finally, we observe an inverse relationship between system complexity and sustainability. Comparative analyses using Monte–Carlo simulations and rate equations are employed, along with analytical arguments, to reinforce the study’s findings. The model successfully captures key aspects of the human-environment system, offering valuable insights to understand how both the spread of information and social dynamics may impact the sustainability of CPRs.
{"title":"Modelling co-evolution of resource feedback and social network dynamics in human-environmental systems","authors":"Meghdad Saeedian, Chengyi Tu, Fabio Menegazzo, Paolo D’Odorico, Sandro Azaele and Samir Suweis","doi":"10.1088/1367-2630/ad67fe","DOIUrl":"https://doi.org/10.1088/1367-2630/ad67fe","url":null,"abstract":"Games with environmental feedback have become a crucial area of study across various scientific domains, modelling the dynamic interplay between human decisions and environmental changes, and highlighting the consequences of our choices on natural resources and biodiversity. In this work, we propose a co-evolutionary model for human-environment systems that incorporates the effects of knowledge feedback and social interaction on the sustainability of common pool resources (CPRs). The model represents consumers as agents who adjust their resource extraction based on the resource’s state. These agents are connected through social networks, where links symbolize either affinity or aversion among them. The interplay between social dynamics and resource dynamics is explored, with the system’s evolution analyzed across various network topologies and initial conditions. We find that knowledge feedback can independently sustain CPRs. However, the impact of social interactions on sustainability is dual-faceted: it can either support or impede sustainability, influenced by the network’s connectivity and heterogeneity. A notable finding is the identification of a critical network mean degree, beyond which a depletion/repletion transition parallels an absorbing/active state transition in social dynamics, i.e. individual agents and their connections are/are not prone to being frozen in their social states. Furthermore, the study examines the evolution of the social network, revealing the emergence of two polarized groups where agents within each community have the same affinity. Finally, we observe an inverse relationship between system complexity and sustainability. Comparative analyses using Monte–Carlo simulations and rate equations are employed, along with analytical arguments, to reinforce the study’s findings. The model successfully captures key aspects of the human-environment system, offering valuable insights to understand how both the spread of information and social dynamics may impact the sustainability of CPRs.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.1088/1367-2630/ad689b
Mordecai Waegell
In single-particle Madelung mechanics, the single-particle quantum state is interpreted as comprising an entire conserved fluid of classical point particles, with local density and local momentum (where R and S are real). The Schrödinger equation gives rise to the continuity equation for the fluid, and the Hamilton–Jacobi equation for particles of the fluid, which includes an additional density-dependent quantum potential energy term , which is all that makes the fluid behavior nonclassical. In particular, the quantum potential can become negative and create a nonclassical boost in the kinetic energy. This boost is related to superoscillations in the wavefunction, where the local frequency of Ψ exceeds its global band limit. Berry showed that for states of definite energy E, the regions of superoscillation are exactly the regions where . For energy superposition states with band-limit , the situation is slightly more complicated, and the bound is no longer . However, the fluid model provides a definite local energy for each fluid particle which allows us to define a local band limit for superoscillation, and with this definition, all regions of superoscillation are again regions where for general superpositions. An alternative interpretation of these quantities involving a reduced quantum potential is reviewed and advanced, and a parallel discussion of superoscillation in this picture is given. Detailed examples are given which illustrate the role of the quantum potential and superoscillations in a range of scenarios.
在单粒子马德龙力学中，单粒子量子态被解释为由经典点粒子组成的整个守恒流体，具有局部密度和局部动量（其中 R 和 S 为实数）。薛定谔方程产生了流体的连续性方程，以及流体粒子的汉密尔顿-贾可比方程，其中包括一个额外的与密度相关的量子势能项，这就是使流体行为非经典化的全部原因。特别是，量子势能可以变为负值，并产生非经典的动能提升。这种提升与波函数中的超振荡有关，在超振荡中，Ψ 的局部频率超过了其全局带限。贝里证明，对于能量 E 确定的态，超振荡区域正是......的区域。对于带限为Ⅴ的能量叠加态，情况略微复杂一些，约束不再是Ⅴ。然而，流体模型为每个流体粒子提供了一个确定的局部能量，这使得我们可以定义超振荡的局部带限，根据这一定义，所有超振荡区域都是一般叠加态的所在区域。我们回顾并提出了这些量的另一种解释，其中涉及量子势的降低，并对这种情况下的超振荡进行了平行讨论。还给出了详细的例子，说明量子势和超稳定在一系列情况下的作用。
{"title":"Madelung mechanics and superoscillations","authors":"Mordecai Waegell","doi":"10.1088/1367-2630/ad689b","DOIUrl":"https://doi.org/10.1088/1367-2630/ad689b","url":null,"abstract":"In single-particle Madelung mechanics, the single-particle quantum state is interpreted as comprising an entire conserved fluid of classical point particles, with local density and local momentum (where R and S are real). The Schrödinger equation gives rise to the continuity equation for the fluid, and the Hamilton–Jacobi equation for particles of the fluid, which includes an additional density-dependent quantum potential energy term , which is all that makes the fluid behavior nonclassical. In particular, the quantum potential can become negative and create a nonclassical boost in the kinetic energy. This boost is related to superoscillations in the wavefunction, where the local frequency of Ψ exceeds its global band limit. Berry showed that for states of definite energy E, the regions of superoscillation are exactly the regions where . For energy superposition states with band-limit , the situation is slightly more complicated, and the bound is no longer . However, the fluid model provides a definite local energy for each fluid particle which allows us to define a local band limit for superoscillation, and with this definition, all regions of superoscillation are again regions where for general superpositions. An alternative interpretation of these quantities involving a reduced quantum potential is reviewed and advanced, and a parallel discussion of superoscillation in this picture is given. Detailed examples are given which illustrate the role of the quantum potential and superoscillations in a range of scenarios.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141941275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1367-2630/ad64fc
Seung Park, Kyunghyun Baek, Seungjin Lee, Mahn-Soo Choi
We present a global optimization routine for the variational quantum algorithms, which utilizes the dynamic tunneling flow. Originally designed to leverage information gathered by a gradient-based optimizer around local minima, we adapt the conventional dynamic tunneling flow to exploit the distance measure of quantum states, resolving issues of extrinsic degeneracy arising from the parametrization of quantum states. Our global optimization algorithm is applied to the variational quantum eigensolver for the transverse-field Ising model to demonstrate the performance of our routine while comparing it with the conventional dynamic tunneling method, which is based on the Euclidean distance measure on the parameter space.
{"title":"Global optimization in variational quantum algorithms via dynamic tunneling method","authors":"Seung Park, Kyunghyun Baek, Seungjin Lee, Mahn-Soo Choi","doi":"10.1088/1367-2630/ad64fc","DOIUrl":"https://doi.org/10.1088/1367-2630/ad64fc","url":null,"abstract":"We present a global optimization routine for the variational quantum algorithms, which utilizes the dynamic tunneling flow. Originally designed to leverage information gathered by a gradient-based optimizer around local minima, we adapt the conventional dynamic tunneling flow to exploit the distance measure of quantum states, resolving issues of extrinsic degeneracy arising from the parametrization of quantum states. Our global optimization algorithm is applied to the variational quantum eigensolver for the transverse-field Ising model to demonstrate the performance of our routine while comparing it with the conventional dynamic tunneling method, which is based on the Euclidean distance measure on the parameter space.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1367-2630/ad60ee
A Touwen, J W F van Hofslot, T Qualm, R Borchers, R Bause, H L Bethlem, A Boeschoten, A Borschevsky, T H Fikkers, S Hoekstra, K Jungmann, V R Marshall, T B Meijknecht, M C Mooij, R G E Timmermans, W Ubachs, L Willmann, NL-eEDM collaboration
An electrostatic hexapole lens is used to manipulate the transverse properties of a beam of barium fluoride molecules from a cryogenic buffer gas source. The spatial distribution of the beam is measured by recording state-selective laser-induced fluorescence on an emccd camera, providing insight into the intensity and transverse position spread of the molecular beam. Although the high mass and unfavorable Stark shift of barium fluoride pose a considerable challenge, the number of molecules in the low-field seeking component of the N = 1 state that pass a 4 mm diameter aperture 712 mm behind the source is increased by a factor of 12. Furthermore, it is demonstrated that the molecular beam can be displaced by up to ±5 mm by moving the hexapole lens. Our measurements agree well with numerical trajectory simulations. We discuss how electrostatic lenses may be used to increase the sensitivity of beam experiments such as the search for the electric dipole moment of the electron.
{"title":"Manipulating a beam of barium fluoride molecules using an electrostatic hexapole","authors":"A Touwen, J W F van Hofslot, T Qualm, R Borchers, R Bause, H L Bethlem, A Boeschoten, A Borschevsky, T H Fikkers, S Hoekstra, K Jungmann, V R Marshall, T B Meijknecht, M C Mooij, R G E Timmermans, W Ubachs, L Willmann, NL-eEDM collaboration","doi":"10.1088/1367-2630/ad60ee","DOIUrl":"https://doi.org/10.1088/1367-2630/ad60ee","url":null,"abstract":"An electrostatic hexapole lens is used to manipulate the transverse properties of a beam of barium fluoride molecules from a cryogenic buffer gas source. The spatial distribution of the beam is measured by recording state-selective laser-induced fluorescence on an <sc>emccd</sc> camera, providing insight into the intensity and transverse position spread of the molecular beam. Although the high mass and unfavorable Stark shift of barium fluoride pose a considerable challenge, the number of molecules in the low-field seeking component of the <italic toggle=\"yes\">N</italic> = 1 state that pass a 4 mm diameter aperture 712 mm behind the source is increased by a factor of 12. Furthermore, it is demonstrated that the molecular beam can be displaced by up to ±5 mm by moving the hexapole lens. Our measurements agree well with numerical trajectory simulations. We discuss how electrostatic lenses may be used to increase the sensitivity of beam experiments such as the search for the electric dipole moment of the electron.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01DOI: 10.1088/1367-2630/ad668c
Hyunsoo Choi, Fanglin Bao, Zubin Jacob
The growth in space activity has increased the need for Space Domain Awareness (SDA) to ensure safe space operations. Imaging and detecting space targets is, however, challenging due to their dim appearance, small angular size/separation, dense distribution, and atmospheric turbulence. These challenges render space targets in ground-based imaging observations as point-like objects in the sub-Rayleigh regime, with extreme brightness contrast but a low photon budget. Here, we propose to use the recently developed quantum-accelerated imaging (QAI) for the SDA challenge. We mainly focus on three SDA challenges (1) minimal a priori assumptions (2) many-object problem (3) extreme brightness ratio. We also present results on source estimation and localization in the presence of atmospheric turbulence. QAI shows significantly improved estimation in position, brightness, and number of targets for all SDA challenges. In particular, we demonstrate up to 2.5 times better performance in source detection than highly optimized direct imaging in extreme scenarios like stars with a 1000 times brightness ratio. With over 10 000 simulations, we verify the increased resolution of our approach compared to conventional state-of-the-art direct imaging paving the way towards quantum optics approaches for SDA.
{"title":"Adaptive quantum accelerated imaging for space domain awareness","authors":"Hyunsoo Choi, Fanglin Bao, Zubin Jacob","doi":"10.1088/1367-2630/ad668c","DOIUrl":"https://doi.org/10.1088/1367-2630/ad668c","url":null,"abstract":"The growth in space activity has increased the need for Space Domain Awareness (SDA) to ensure safe space operations. Imaging and detecting space targets is, however, challenging due to their dim appearance, small angular size/separation, dense distribution, and atmospheric turbulence. These challenges render space targets in ground-based imaging observations as point-like objects in the sub-Rayleigh regime, with extreme brightness contrast but a low photon budget. Here, we propose to use the recently developed quantum-accelerated imaging (QAI) for the SDA challenge. We mainly focus on three SDA challenges (1) minimal <italic toggle=\"yes\">a priori</italic> assumptions (2) many-object problem (3) extreme brightness ratio. We also present results on source estimation and localization in the presence of atmospheric turbulence. QAI shows significantly improved estimation in position, brightness, and number of targets for all SDA challenges. In particular, we demonstrate up to 2.5 times better performance in source detection than highly optimized direct imaging in extreme scenarios like stars with a 1000 times brightness ratio. With over 10 000 simulations, we verify the increased resolution of our approach compared to conventional state-of-the-art direct imaging paving the way towards quantum optics approaches for SDA.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-31DOI: 10.1088/1367-2630/ad668b
Zijie Chen, Yuxin Geng, Xingru Chen, Feng Fu
Evolutionary game dynamics on networks typically consider the competition among simple strategies such as cooperation and defection in the Prisoner’s Dilemma and summarize the effect of population structure as network reciprocity. However, it remains largely unknown regarding the evolutionary dynamics involving multiple powerful strategies typically considered in repeated games, such as the zero-determinant (ZD) strategies that are able to enforce a linear payoff relationship between them and their co-players. Here, we consider the evolutionary dynamics of always cooperate (AllC), extortionate ZD (extortioners), and unbending players in lattice populations based on the commonly used death-birth updating. Out of the class of unbending strategies that can foster reciprocal cooperation and fairness among extortionate players, we consider a particular candidate, pre-optimized through the machine-learning method of particle swarm optimization (PSO), called PSO Gambler. We derive analytical results under weak selection and rare mutations, including pairwise fixation probabilities and long-term frequencies of strategies. In the absence of the third unbending type, extortioners can achieve a half-half split in equilibrium with unconditional cooperators for sufficiently large extortion factors. However, the presence of unbending players fundamentally changes the dynamics and tilts the system to favor unbending cooperation. Most surprisingly, extortioners cannot dominate at all regardless of how large their extortion factor is, and the long-term frequency of unbending players is maintained almost as a constant. Our analytical method is applicable to studying the evolutionary dynamics of multiple strategies in structured populations. Our work provides insights into the interplay between network reciprocity and direct reciprocity, revealing the role of unbending strategies in enforcing fairness and suppressing extortion.
{"title":"Unbending strategies shepherd cooperation and suppress extortion in spatial populations","authors":"Zijie Chen, Yuxin Geng, Xingru Chen, Feng Fu","doi":"10.1088/1367-2630/ad668b","DOIUrl":"https://doi.org/10.1088/1367-2630/ad668b","url":null,"abstract":"Evolutionary game dynamics on networks typically consider the competition among simple strategies such as cooperation and defection in the Prisoner’s Dilemma and summarize the effect of population structure as network reciprocity. However, it remains largely unknown regarding the evolutionary dynamics involving multiple powerful strategies typically considered in repeated games, such as the zero-determinant (ZD) strategies that are able to enforce a linear payoff relationship between them and their co-players. Here, we consider the evolutionary dynamics of always cooperate (AllC), extortionate ZD (extortioners), and unbending players in lattice populations based on the commonly used death-birth updating. Out of the class of unbending strategies that can foster reciprocal cooperation and fairness among extortionate players, we consider a particular candidate, pre-optimized through the machine-learning method of particle swarm optimization (PSO), called PSO Gambler. We derive analytical results under weak selection and rare mutations, including pairwise fixation probabilities and long-term frequencies of strategies. In the absence of the third unbending type, extortioners can achieve a half-half split in equilibrium with unconditional cooperators for sufficiently large extortion factors. However, the presence of unbending players fundamentally changes the dynamics and tilts the system to favor unbending cooperation. Most surprisingly, extortioners cannot dominate at all regardless of how large their extortion factor is, and the long-term frequency of unbending players is maintained almost as a constant. Our analytical method is applicable to studying the evolutionary dynamics of multiple strategies in structured populations. Our work provides insights into the interplay between network reciprocity and direct reciprocity, revealing the role of unbending strategies in enforcing fairness and suppressing extortion.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-31DOI: 10.1088/1367-2630/ad6349
Manish Patel, Debasish Chaudhuri
In this study, we investigate the behavior of inertial active Brownian particles in a d-dimensional harmonic trap in the presence of translational diffusion. While the solution of the Fokker–Planck equation is generally challenging, it can be utilized to compute the exact time evolution of all time-dependent dynamical moments using a Laplace transform approach. We present the explicit form for several moments of position and velocity in d-dimensions. An interplay of time scales assures that the effective diffusivity and steady-state kinetic temperature depend on both inertia and trap strength, unlike passive systems. The distance from equilibrium, measured by the violation of equilibrium fluctuation-dissipation and the amount of entropy production, decreases with increasing inertia and trap strength. We present detailed ‘phase diagrams’ using kurtosis of velocity and position, showing possibilities of re-entrance to equilibrium.
在本研究中，我们研究了存在平移扩散的 d 维谐波陷阱中惯性活动布朗粒子的行为。虽然福克-普朗克方程的求解通常具有挑战性，但我们可以利用拉普拉斯变换方法计算所有与时间相关的动态时刻的精确时间演化。我们介绍了 d 维中位置和速度的几个时刻的显式形式。与被动系统不同的是，时间尺度的相互作用确保了有效扩散率和稳态动力学温度同时取决于惯性和陷阱强度。随着惯性和陷阱强度的增加，以违反平衡的波动-耗散和熵产生量来衡量的平衡距离会减小。我们利用速度和位置的峰度提出了详细的 "相图"，显示了重新进入平衡的可能性。
{"title":"Exact moments for trapped active particles: inertial impact on steady-state properties and re-entrance","authors":"Manish Patel, Debasish Chaudhuri","doi":"10.1088/1367-2630/ad6349","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6349","url":null,"abstract":"In this study, we investigate the behavior of inertial active Brownian particles in a <italic toggle=\"yes\">d</italic>-dimensional harmonic trap in the presence of translational diffusion. While the solution of the Fokker–Planck equation is generally challenging, it can be utilized to compute the exact time evolution of all time-dependent dynamical moments using a Laplace transform approach. We present the explicit form for several moments of position and velocity in <italic toggle=\"yes\">d</italic>-dimensions. An interplay of time scales assures that the effective diffusivity and steady-state kinetic temperature depend on both inertia and trap strength, unlike passive systems. The distance from equilibrium, measured by the violation of equilibrium fluctuation-dissipation and the amount of entropy production, decreases with increasing inertia and trap strength. We present detailed ‘phase diagrams’ using kurtosis of velocity and position, showing possibilities of re-entrance to equilibrium.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-31DOI: 10.1088/1367-2630/ad6348
Zamir Beleño, Marcelo F Santos, Felipe Barra
The interaction of a three-level atom with the electromagnetic field of a quantum cavity in the presence of a laser field presents a rich behavior in the dispersive regime that we exploit to discuss two quantum batteries. In the first setup, we consider a single three-level atom interacting sequentially with many cavities, each in a thermal state. We show that under this process, the atom converges towards an equilibrium state that displays population inversion. In the second setup, a stream of atoms in a thermal state interacts sequentially with a single cavity initially in a thermal state at the same temperature as the atoms. We show that the cavity’s energy increases continuously as the stream of atoms continues to cross, and the cavity does not reach an equilibrium state. After many atoms have traveled, the cavity’s state becomes active, storing extractable energy that increases in proportion to the work done by the laser. However, the same dynamics may involve only two cavity levels in an interesting limit called the highly selective regime. In that regime, the cavity reaches an equilibrium state similar to the one of the atom in the first scenario. The charging process we propose is robust. We discuss its thermodynamics and evaluate the energy supplied by the laser, the energy stored in the battery, and, thus, the device’s efficiency. We also analyze the role of damping.
{"title":"Laser powered dissipative quantum batteries in atom-cavity QED","authors":"Zamir Beleño, Marcelo F Santos, Felipe Barra","doi":"10.1088/1367-2630/ad6348","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6348","url":null,"abstract":"The interaction of a three-level atom with the electromagnetic field of a quantum cavity in the presence of a laser field presents a rich behavior in the dispersive regime that we exploit to discuss two quantum batteries. In the first setup, we consider a single three-level atom interacting sequentially with many cavities, each in a thermal state. We show that under this process, the atom converges towards an equilibrium state that displays population inversion. In the second setup, a stream of atoms in a thermal state interacts sequentially with a single cavity initially in a thermal state at the same temperature as the atoms. We show that the cavity’s energy increases continuously as the stream of atoms continues to cross, and the cavity does not reach an equilibrium state. After many atoms have traveled, the cavity’s state becomes active, storing extractable energy that increases in proportion to the work done by the laser. However, the same dynamics may involve only two cavity levels in an interesting limit called the highly selective regime. In that regime, the cavity reaches an equilibrium state similar to the one of the atom in the first scenario. The charging process we propose is robust. We discuss its thermodynamics and evaluate the energy supplied by the laser, the energy stored in the battery, and, thus, the device’s efficiency. We also analyze the role of damping.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-30DOI: 10.1088/1367-2630/ad6584
Fanglin Bao, Leif Bauer, Adrián E Rubio López, Ziyi Yang, Xueji Wang, Zubin Jacob
Photon statistics of an optical field can be used for quantum optical sensing in low light level scenarios free of bulky optical components. However, photon-number-resolving detection to unravel the photon statistics is challenging. Here, we propose a novel detection approach, that we call ‘photon discerning’, which uses adaptive photon thresholding for photon statistical estimation without recording exact photon numbers. Our photon discerner is motivated by the field of neural networks where tunable thresholds have proven efficient for information extraction in machine learning tasks. The photon discerner maximizes Fisher information per photon by iteratively choosing the optimal threshold in real-time to approach the shot noise limit. Our proposed scheme of adaptive photon thresholding leads to unique remote-sensing applications of quantum degree of linear polarization camera and quantum LiDAR. We investigate optimal thresholds and show that the optimal photon threshold can be counter-intuitive (not equal to 1) even for weak signals (mean photon number much less than 1), due to the photon bunching effect. We also put forth a superconducting nanowire realization of the photon discerner which can be experimentally implemented in the near-term. We show that the adaptivity of our photon discerner enables it to beat realistic photon-number-resolving detectors with limited photon-number resolution in certain applications. Our work suggests a new class of detectors for information-theory driven, compact, and learning-based quantum optical sensing.
{"title":"Photon discerner: adaptive quantum optical sensing near the shot noise limit","authors":"Fanglin Bao, Leif Bauer, Adrián E Rubio López, Ziyi Yang, Xueji Wang, Zubin Jacob","doi":"10.1088/1367-2630/ad6584","DOIUrl":"https://doi.org/10.1088/1367-2630/ad6584","url":null,"abstract":"Photon statistics of an optical field can be used for quantum optical sensing in low light level scenarios free of bulky optical components. However, photon-number-resolving detection to unravel the photon statistics is challenging. Here, we propose a novel detection approach, that we call ‘photon discerning’, which uses adaptive photon thresholding for photon statistical estimation without recording exact photon numbers. Our photon discerner is motivated by the field of neural networks where tunable thresholds have proven efficient for information extraction in machine learning tasks. The photon discerner maximizes Fisher information per photon by iteratively choosing the optimal threshold in real-time to approach the shot noise limit. Our proposed scheme of adaptive photon thresholding leads to unique remote-sensing applications of quantum degree of linear polarization camera and quantum LiDAR. We investigate optimal thresholds and show that the optimal photon threshold can be counter-intuitive (not equal to 1) even for weak signals (mean photon number much less than 1), due to the photon bunching effect. We also put forth a superconducting nanowire realization of the photon discerner which can be experimentally implemented in the near-term. We show that the adaptivity of our photon discerner enables it to beat realistic photon-number-resolving detectors with limited photon-number resolution in certain applications. Our work suggests a new class of detectors for information-theory driven, compact, and learning-based quantum optical sensing.","PeriodicalId":19181,"journal":{"name":"New Journal of Physics","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141866914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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