Pub Date : 2024-08-12DOI: 10.1103/physreva.110.023312
Jeff Maki, Fei Zhou
Conformal symmetry heavily constrains the dynamics of nonrelativistic quantum gases tuned to a nearby quantum critical point. One important consequence of this symmetry is that entropy production can be absent in far-away-from-equilibrium dynamics of strongly interacting three-dimensional (3D) and one-dimensional (1D) quantum gases placed inside an adjustable harmonic trapping potential. This can lead to an oscillatory fully revivable many-body dynamic state, which is reflected in many physical observables. In this article we further investigate the consequences of conformal symmetry on (a) the zero-temperature autocorrelation function, (b) the Wigner distribution function, and (c) the von Neumann entanglement entropy. A direct calculation of these quantities for generic strongly interacting systems is usually extremely difficult. However, we have derived the general structures of these functions in the nonequilibrium dynamics when their dynamics are constrained by conformal symmetry. We obtain our results for (a) by utilizing an operator-state correspondence which connects the imaginary time evolution of primary operators to different initial states of harmonically trapped gases, while the dynamics of the functions in (b) and (c) are derived from conformal invariant density matrices.
{"title":"Signatures of conformal symmetry in the dynamics of quantum gases: A cyclic quantum state and entanglement entropy","authors":"Jeff Maki, Fei Zhou","doi":"10.1103/physreva.110.023312","DOIUrl":"https://doi.org/10.1103/physreva.110.023312","url":null,"abstract":"Conformal symmetry heavily constrains the dynamics of nonrelativistic quantum gases tuned to a nearby quantum critical point. One important consequence of this symmetry is that entropy production can be absent in far-away-from-equilibrium dynamics of strongly interacting three-dimensional (3D) and one-dimensional (1D) quantum gases placed inside an adjustable harmonic trapping potential. This can lead to an oscillatory fully revivable many-body dynamic state, which is reflected in many physical observables. In this article we further investigate the consequences of conformal symmetry on (a) the zero-temperature autocorrelation function, (b) the Wigner distribution function, and (c) the von Neumann entanglement entropy. A direct calculation of these quantities for generic strongly interacting systems is usually extremely difficult. However, we have derived the general structures of these functions in the nonequilibrium dynamics when their dynamics are constrained by conformal symmetry. We obtain our results for (a) by utilizing an operator-state correspondence which connects the imaginary time evolution of primary operators to different initial states of harmonically trapped gases, while the dynamics of the functions in (b) and (c) are derived from conformal invariant density matrices.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943309","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}
Spin-orbit interaction (SOI) due to the tight focusing of light in optical tweezers has led to exciting and exotic avenues towards inducing rotation in microscopic particles. However, instances where the back action of the particles influences and modifies SOI effects so as to induce rotational motion are rarely known. Here we tightly focus a vector beam having radial/azimuthal polarization carrying no intrinsic angular momentum into a refractive index stratified medium and observe the orbital rotation of birefringent particles around the beam propagation axis. In order to validate our experimental findings, we perform numerical simulations of the governing equations. Our simulations reveal that the interaction of light with a birefringent particle gives rise to inhomogeneous spin currents near the focus, resulting in a finite spin momentum. This spin momentum combines with the canonical momentum to finally generate an origin-dependent orbital angular momentum, which is manifested in the rotation of the birefringent particles around the beam axis. Our study describes a unique modulation of the SOI of light due to its interaction with anisotropic particles that can open up new avenues for exotic and complex particle manipulation in optical tweezers.
光学镊子对光线的紧密聚焦所产生的自旋轨道相互作用（SOI）为诱导微观粒子旋转提供了令人兴奋的奇特途径。然而，粒子的反作用会影响和改变 SOI 效应，从而诱发旋转运动的情况却鲜为人知。在这里，我们将不携带固有角动量的径向/方位偏振矢量光束紧密聚焦到折射率分层介质中，观察双折射粒子围绕光束传播轴的轨道旋转。为了验证实验结果，我们对控制方程进行了数值模拟。模拟结果表明，光与双折射粒子的相互作用会在焦点附近产生不均匀的自旋电流，从而产生有限的自旋动量。这种自旋动量与标准动量相结合，最终产生了与原点相关的轨道角动量，表现为双折射粒子绕光束轴的旋转。我们的研究描述了由于光与各向异性粒子的相互作用而对光的 SOI 产生的独特调制，这为在光镊中进行奇特而复杂的粒子操纵开辟了新的途径。
{"title":"Inhomogeneous-spin-momentum-induced orbital motion of birefringent particles in tight focusing of vector beams in optical tweezers","authors":"Ram Nandan Kumar, Anand Dev Ranjan, Sauvik Roy, Subhasish Dutta Gupta, Nirmalya Ghosh, Ayan Banerjee","doi":"10.1103/physreva.110.023512","DOIUrl":"https://doi.org/10.1103/physreva.110.023512","url":null,"abstract":"Spin-orbit interaction (SOI) due to the tight focusing of light in optical tweezers has led to exciting and exotic avenues towards inducing rotation in microscopic particles. However, instances where the back action of the particles influences and modifies SOI effects so as to induce rotational motion are rarely known. Here we tightly focus a vector beam having radial/azimuthal polarization carrying no intrinsic angular momentum into a refractive index stratified medium and observe the orbital rotation of birefringent particles around the beam propagation axis. In order to validate our experimental findings, we perform numerical simulations of the governing equations. Our simulations reveal that the interaction of light with a birefringent particle gives rise to inhomogeneous spin currents near the focus, resulting in a finite spin momentum. This spin momentum combines with the canonical momentum to finally generate an origin-dependent orbital angular momentum, which is manifested in the rotation of the birefringent particles around the beam axis. Our study describes a unique modulation of the SOI of light due to its interaction with anisotropic particles that can open up new avenues for exotic and complex particle manipulation in optical tweezers.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943307","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}
We investigate violations of Leggett-Garg inequalities (LGIs) for a harmonic oscillator and a -dimensional chiral scalar field with coherent-state projectors, which is equivalent to a heterodyne-type measurement scheme. For the harmonic oscillator, we found that the vacuum and thermal states violated the LGIs by evaluating the two-time quasiprobability distribution function. In particular, we demonstrate that the value of the two-time quasiprobability reaches for a squeezed coherent-state projector, which is equivalent to of the Lüders bound corresponding to the maximal violation of the LGIs. We also find a violation of the LGIs for the local mode of a quantum chiral scalar field by constructing a coherent-state projector similar to the harmonic-oscillator case. In contrast with the harmonic oscillator, the periodicity in the time direction of the quasiprobability disappears, which is related to the existence of quantum entanglement between the local mode and its complementary degrees of freedom.
{"title":"Large violation of Leggett-Garg inequalities with coherent-state projectors for a harmonic oscillator and chiral scalar field","authors":"Tomoya Hirotani, Akira Matsumura, Yasusada Nambu, Kazuhiro Yamamoto","doi":"10.1103/physreva.110.022217","DOIUrl":"https://doi.org/10.1103/physreva.110.022217","url":null,"abstract":"We investigate violations of Leggett-Garg inequalities (LGIs) for a harmonic oscillator and a <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>(</mo><mn>1</mn><mo>+</mo><mn>1</mn><mo>)</mo></mrow></math>-dimensional chiral scalar field with coherent-state projectors, which is equivalent to a heterodyne-type measurement scheme. For the harmonic oscillator, we found that the vacuum and thermal states violated the LGIs by evaluating the two-time quasiprobability distribution function. In particular, we demonstrate that the value of the two-time quasiprobability reaches <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>−</mo><mn>0.123</mn></mrow></math> for a squeezed coherent-state projector, which is equivalent to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>98</mn><mo>%</mo></mrow></math> of the Lüders bound corresponding to the maximal violation of the LGIs. We also find a violation of the LGIs for the local mode of a quantum chiral scalar field by constructing a coherent-state projector similar to the harmonic-oscillator case. In contrast with the harmonic oscillator, the periodicity in the time direction of the quasiprobability disappears, which is related to the existence of quantum entanglement between the local mode and its complementary degrees of freedom.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943406","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 : 2024-08-09DOI: 10.1103/physreva.110.022414
Frieder Lindel, Alexa Herter, Valentin Gebhart, Jérôme Faist, Stefan Yoshi Buhmann
In many states of the quantum electromagnetic field, including the vacuum state, entanglement exists between different space-time regions—even spacelike separated ones. These correlations can be harvested and, thereby, detected by quantum systems which locally interact with the field. Here, we propose an experimental implementation of such an entanglement-harvesting scheme which is based on electro-optic sampling (EOS). We demonstrate that state-of-the-art EOS experiments enable one to harvest entanglement from the vacuum field and to study quantum correlations within general THz fields. We further show how Bell nonlocality present in the vacuum field can be probed. Finally, we introduce an approach to mitigate shot noise in single-beam EOS configurations. These findings pave the way for experimental inquiries into foundational properties of relativistic quantum field theory, and empower EOS as a diagnostic tool in THz quantum optics.
在量子电磁场的许多状态下，包括真空状态，不同时空区域--甚至是相距甚远的时空区域--之间存在着纠缠。这些相关性可以被局部与电磁场相互作用的量子系统捕获并探测到。在这里，我们提出了一种基于电光采样（EOS）的纠缠捕获实验方案。我们证明，最先进的 EOS 实验能够从真空场中收获纠缠，并研究一般太赫兹场中的量子相关性。我们进一步展示了如何探测真空场中存在的贝尔非局域性。最后，我们介绍了一种在单光束 EOS 配置中减轻射出噪声的方法。这些发现为相对论量子场论基础特性的实验探索铺平了道路，并使 EOS 成为太赫兹量子光学的诊断工具。
{"title":"Entanglement harvesting from electromagnetic quantum fields","authors":"Frieder Lindel, Alexa Herter, Valentin Gebhart, Jérôme Faist, Stefan Yoshi Buhmann","doi":"10.1103/physreva.110.022414","DOIUrl":"https://doi.org/10.1103/physreva.110.022414","url":null,"abstract":"In many states of the quantum electromagnetic field, including the vacuum state, entanglement exists between different space-time regions—even spacelike separated ones. These correlations can be harvested and, thereby, detected by quantum systems which locally interact with the field. Here, we propose an experimental implementation of such an entanglement-harvesting scheme which is based on electro-optic sampling (EOS). We demonstrate that state-of-the-art EOS experiments enable one to harvest entanglement from the vacuum field and to study quantum correlations within general THz fields. We further show how Bell nonlocality present in the vacuum field can be probed. Finally, we introduce an approach to mitigate shot noise in single-beam EOS configurations. These findings pave the way for experimental inquiries into foundational properties of relativistic quantum field theory, and empower EOS as a diagnostic tool in THz quantum optics.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943311","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 : 2024-08-08DOI: 10.1103/physreva.110.022607
Yifan Hong, Matteo Marinelli, Adam M. Kaufman, Andrew Lucas
The surface code is a quantum error-correcting code for one logical qubit, protected by spatially localized parity checks in two dimensions. Due to fundamental constraints from spatial locality, storing more logical qubits requires either sacrificing the robustness of the surface code against errors or increasing the number of physical qubits. We bound the minimal number of spatially nonlocal parity checks necessary to add logical qubits to a surface code while maintaining, or improving, robustness to errors. We saturate the lower limit of this bound, when the number of added logical qubits is a constant, using a family of hypergraph product codes, interpolating between the surface code and constant-rate low-density parity-check codes. Fault-tolerant protocols for logical gates in the quantum code can be inherited from its classical parent codes. We provide near-term practical implementations of this code for hardware based on trapped ions or neutral atoms in mobile optical tweezers. Long-range-enhanced surface codes outperform conventional surface codes using hundreds of physical qubits, and they represent a practical strategy to enhance the robustness of logical qubits to errors in near-term devices.
{"title":"Long-range-enhanced surface codes","authors":"Yifan Hong, Matteo Marinelli, Adam M. Kaufman, Andrew Lucas","doi":"10.1103/physreva.110.022607","DOIUrl":"https://doi.org/10.1103/physreva.110.022607","url":null,"abstract":"The surface code is a quantum error-correcting code for one logical qubit, protected by spatially localized parity checks in two dimensions. Due to fundamental constraints from spatial locality, storing more logical qubits requires either sacrificing the robustness of the surface code against errors or increasing the number of physical qubits. We bound the minimal number of spatially nonlocal parity checks necessary to add logical qubits to a surface code while maintaining, or improving, robustness to errors. We saturate the lower limit of this bound, when the number of added logical qubits is a constant, using a family of hypergraph product codes, interpolating between the surface code and constant-rate low-density parity-check codes. Fault-tolerant protocols for logical gates in the quantum code can be inherited from its classical parent codes. We provide near-term practical implementations of this code for hardware based on trapped ions or neutral atoms in mobile optical tweezers. Long-range-enhanced surface codes outperform conventional surface codes using hundreds of physical qubits, and they represent a practical strategy to enhance the robustness of logical qubits to errors in near-term devices.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943410","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 : 2024-08-08DOI: 10.1103/physreva.110.023309
Alexander Yu. Cherny
The confinement-induced resonances for trapped bosons in the cigar-shaped and pancake geometries are studied within the generalized Gross-Pitaevskii equations, which are a simplified version of the Hartree-Fock-Bogoliubov approximation. Although the Hartree-Fock-Bogoliubov method is considered applicable only for small interparticle interactions, the resonance denominators for the chemical potential are obtained in both quasi-one and quasi-two dimensions. A useful integral representation of the one-particle Green's function are found for the cylindrical confinement. We find the position of a smoothed resonance for the chemical potential in the pancake geometry at positive scattering length.
{"title":"Confinement-induced resonance from the generalized Gross-Pitaevskii equations","authors":"Alexander Yu. Cherny","doi":"10.1103/physreva.110.023309","DOIUrl":"https://doi.org/10.1103/physreva.110.023309","url":null,"abstract":"The confinement-induced resonances for trapped bosons in the cigar-shaped and pancake geometries are studied within the generalized Gross-Pitaevskii equations, which are a simplified version of the Hartree-Fock-Bogoliubov approximation. Although the Hartree-Fock-Bogoliubov method is considered applicable only for small interparticle interactions, the resonance denominators for the chemical potential are obtained in both quasi-one and quasi-two dimensions. A useful integral representation of the one-particle Green's function are found for the cylindrical confinement. We find the position of a smoothed resonance for the chemical potential in the pancake geometry at positive scattering length.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943413","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}
Matter-wave interferometers with microparticles will enable the next generation of quantum sensors to probe minute quantum phase information. Therefore, estimating the loss of coherence and the degree of entanglement degradation for such interferometers is essential. In this paper, we provide a noise analysis in frequency-space focusing on electromagnetic sources of dephasing. We assume that our matter-wave interferometer has a residual charge or dipole which can interact with a neighboring particle in the ambience. We investigate the dephasing due to the Coulomb, charge-induced dipole, charge-permanent dipole, and dipole-dipole interactions. All these interactions constitute electromagnetically driven dephasing channels that can affect single or multiple interferometers. As an example, we apply the obtained formulas to situations with two adjacent microparticles, which can provide insight for the noise analysis in the quantum gravity-induced entanglement of masses (QGEM) protocol and the c-not gate: we compute the dephasing due to a gas of environmental particles interacting via dipole-dipole and charge-charge couplings, respectively. To obtain simple analytical dephasing formulas, we employ uniform probability distributions for the impact parameter and for the angles characterizing the relative orientation with respect to the interferometer and a Gaussian distribution for the velocities of the environmental particles. In both cases, we show that the dephasing rate grows with the number density of particles present in the vacuum chamber, as expected.
{"title":"Dephasing due to electromagnetic interactions in spatial qubits","authors":"Martine Schut, Herre Bosma, MengZhi Wu, Marko Toroš, Sougato Bose, Anupam Mazumdar","doi":"10.1103/physreva.110.022412","DOIUrl":"https://doi.org/10.1103/physreva.110.022412","url":null,"abstract":"Matter-wave interferometers with microparticles will enable the next generation of quantum sensors to probe minute quantum phase information. Therefore, estimating the loss of coherence and the degree of entanglement degradation for such interferometers is essential. In this paper, we provide a noise analysis in frequency-space focusing on electromagnetic sources of dephasing. We assume that our matter-wave interferometer has a residual charge or dipole which can interact with a neighboring particle in the ambience. We investigate the dephasing due to the Coulomb, charge-induced dipole, charge-permanent dipole, and dipole-dipole interactions. All these interactions constitute electromagnetically driven dephasing channels that can affect single or multiple interferometers. As an example, we apply the obtained formulas to situations with two adjacent microparticles, which can provide insight for the noise analysis in the quantum gravity-induced entanglement of masses (QGEM) protocol and the <span>c-not</span> gate: we compute the dephasing due to a gas of environmental particles interacting via dipole-dipole and charge-charge couplings, respectively. To obtain simple analytical dephasing formulas, we employ uniform probability distributions for the impact parameter and for the angles characterizing the relative orientation with respect to the interferometer and a Gaussian distribution for the velocities of the environmental particles. In both cases, we show that the dephasing rate grows with the number density of particles present in the vacuum chamber, as expected.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943416","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 : 2024-08-08DOI: 10.1103/physreva.110.023712
Mihai A. Macovei
The quantum dynamics of a dense and dipole-dipole-coupled ensemble of two-level emitters interacting via their environmental thermostat is investigated. The static dipole-dipole interaction strengths are being considered strong enough but smaller than the transition frequency. Therefore, the established thermal equilibrium of ensemble's quantum dynamics is described with respect to the dipole-dipole-coupling strengths. We have demonstrated the quantum nature of the spontaneously scattered light field in this process for weaker thermal baths as well as non-negligible dipole-dipole couplings compared to the emitter's transition frequency. Furthermore, the collectively emitted photon intensity suppresses or enhances depending on the environmental thermal baths' intensities.
{"title":"Dense dipole-dipole-coupled two-level systems in a thermal bath","authors":"Mihai A. Macovei","doi":"10.1103/physreva.110.023712","DOIUrl":"https://doi.org/10.1103/physreva.110.023712","url":null,"abstract":"The quantum dynamics of a dense and dipole-dipole-coupled ensemble of two-level emitters interacting via their environmental thermostat is investigated. The static dipole-dipole interaction strengths are being considered strong enough but smaller than the transition frequency. Therefore, the established thermal equilibrium of ensemble's quantum dynamics is described with respect to the dipole-dipole-coupling strengths. We have demonstrated the quantum nature of the spontaneously scattered light field in this process for weaker thermal baths as well as non-negligible dipole-dipole couplings compared to the emitter's transition frequency. Furthermore, the collectively emitted photon intensity suppresses or enhances depending on the environmental thermal baths' intensities.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943408","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 : 2024-08-08DOI: 10.1103/physreva.110.023104
Wanzhu He, Ning Sun, Xiaosong Zhu, Liang Li, Pengfei Lan, Peixiang Lu
Under intense laser fields, atoms undergo core polarization, i.e., redistribution of the electron density around the nucleus. We systematically investigate the effect of core polarization on high-order harmonic generation (HHG) from solids using time-dependent density-functional theory in a laser-driven linear chain of atoms. It is shown that the presence of core polarization induces substantial variations in HHG compared with the results with a frozen core. Our study further provides insight into these phenomena by combining an approach that distinguishes the effects of core polarization from different shells and compares the contributions of inner and outer shells. Ultimately, we propose and demonstrate a two-color pump-probe scheme to effectively control the core-polarization effects, specifically by activating inner-shell electrons. This work highlights the significance of multielectron effects for solids and demonstrates the feasibility of manipulating the physical properties of materials through core polarization.
{"title":"Laser-induced core-polarization effects in high-order harmonic generation from solids","authors":"Wanzhu He, Ning Sun, Xiaosong Zhu, Liang Li, Pengfei Lan, Peixiang Lu","doi":"10.1103/physreva.110.023104","DOIUrl":"https://doi.org/10.1103/physreva.110.023104","url":null,"abstract":"Under intense laser fields, atoms undergo core polarization, i.e., redistribution of the electron density around the nucleus. We systematically investigate the effect of core polarization on high-order harmonic generation (HHG) from solids using time-dependent density-functional theory in a laser-driven linear chain of atoms. It is shown that the presence of core polarization induces substantial variations in HHG compared with the results with a frozen core. Our study further provides insight into these phenomena by combining an approach that distinguishes the effects of core polarization from different shells and compares the contributions of inner and outer shells. Ultimately, we propose and demonstrate a two-color pump-probe scheme to effectively control the core-polarization effects, specifically by activating inner-shell electrons. This work highlights the significance of multielectron effects for solids and demonstrates the feasibility of manipulating the physical properties of materials through core polarization.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943412","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 : 2024-08-08DOI: 10.1103/physreva.110.022411
Tak Hur, Israel F. Araujo, Daniel K. Park
Quantum embedding is a fundamental prerequisite for applying quantum machine learning techniques to classical data and has substantial impacts on performance outcomes. In this study, we present neural quantum embedding (NQE), a method that efficiently optimizes quantum embedding beyond the limitations of positive and trace-preserving maps by leveraging classical deep-learning techniques. NQE enhances the lower bound of the empirical risk, leading to substantial improvements in classification performance. Moreover, NQE improves robustness against noise. To validate the effectiveness of NQE, we conduct experiments on IBM quantum devices for image data classification, resulting in a remarkable accuracy enhancement from 0.52 to 0.96. In addition, numerical analyses highlight that NQE simultaneously improves the trainability and generalization performance of quantum neural networks, as well as of the quantum kernel method.
{"title":"Neural quantum embedding: Pushing the limits of quantum supervised learning","authors":"Tak Hur, Israel F. Araujo, Daniel K. Park","doi":"10.1103/physreva.110.022411","DOIUrl":"https://doi.org/10.1103/physreva.110.022411","url":null,"abstract":"Quantum embedding is a fundamental prerequisite for applying quantum machine learning techniques to classical data and has substantial impacts on performance outcomes. In this study, we present neural quantum embedding (NQE), a method that efficiently optimizes quantum embedding beyond the limitations of positive and trace-preserving maps by leveraging classical deep-learning techniques. NQE enhances the lower bound of the empirical risk, leading to substantial improvements in classification performance. Moreover, NQE improves robustness against noise. To validate the effectiveness of NQE, we conduct experiments on IBM quantum devices for image data classification, resulting in a remarkable accuracy enhancement from 0.52 to 0.96. In addition, numerical analyses highlight that NQE simultaneously improves the trainability and generalization performance of quantum neural networks, as well as of the quantum kernel method.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141943420","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：