Pub Date : 2024-09-18DOI: 10.1103/physreva.110.032424
Mahadevan Subramanian, Sai Vinjanampathy
The task of discriminating between two known quantum channels is a well-known binary-hypothesis-testing task. We present a variational quantum algorithm with a parameterized state preparation and two-outcome positive operator-valued measure which defines the acceptance criteria for the hypothesis test. Both the state preparation and measurement are simultaneously optimized using the success probability of single-shot discrimination as an objective function which can be calculated using localized measurements. Under constrained signal-mode photon-number quantum illumination we match the performance of known optimal two-mode probes by simulating a bosonic circuit. Our results show that variational algorithms can prepare optimal states for binary hypothesis testing with resource constraints.
{"title":"Shallow-depth variational quantum hypothesis testing","authors":"Mahadevan Subramanian, Sai Vinjanampathy","doi":"10.1103/physreva.110.032424","DOIUrl":"https://doi.org/10.1103/physreva.110.032424","url":null,"abstract":"The task of discriminating between two known quantum channels is a well-known binary-hypothesis-testing task. We present a variational quantum algorithm with a parameterized state preparation and two-outcome positive operator-valued measure which defines the acceptance criteria for the hypothesis test. Both the state preparation and measurement are simultaneously optimized using the success probability of single-shot discrimination as an objective function which can be calculated using localized measurements. Under constrained signal-mode photon-number quantum illumination we match the performance of known optimal two-mode probes by simulating a bosonic circuit. Our results show that variational algorithms can prepare optimal states for binary hypothesis testing with resource constraints.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"51 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262769","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 : 2024-09-18DOI: 10.1103/physreva.110.032423
Anuj K. Nayak, Eric Chitambar, Lav R. Varshney
Quantum memory systems are vital in quantum information processing for dependable storage and retrieval of quantum states. Inspired by classical reliability theories that synthesize reliable computing systems from unreliable components, we formalize the problem of reliable storage of quantum information using noisy components. We introduce the notion of stable quantum memories and define the storage rate as the ratio of the number of logical qubits to the total number of physical qubits as well as the circuit complexity of the decoder, which includes both quantum gates and measurements. We demonstrate that a strictly positive storage rate can be achieved by constructing a quantum memory system with quantum expander codes. Moreover, by reducing the reliable storage problem to reliable quantum communication, we provide upper bounds on the achievable storage capacity. In the case of physical qubits corrupted by noise satisfying hypercontractivity conditions, we provide a tighter upper bound on storage capacity using an entropy dissipation argument. Furthermore, observing that the time complexity of the decoder scales nontrivially with the number of physical qubits, achieving asymptotic rates may not be possible due to the induced dependence of the noise on the number of physical qubits. In this constrained nonasymptotic setting, we derive upper bounds on storage capacity using finite blocklength communication bounds. Finally, we numerically analyze the gap between upper and lower bounds in both asymptotic and nonasymptotic cases, and provide suggestions to tighten the gap.
{"title":"Reliable quantum memories with unreliable components","authors":"Anuj K. Nayak, Eric Chitambar, Lav R. Varshney","doi":"10.1103/physreva.110.032423","DOIUrl":"https://doi.org/10.1103/physreva.110.032423","url":null,"abstract":"Quantum memory systems are vital in quantum information processing for dependable storage and retrieval of quantum states. Inspired by classical reliability theories that synthesize reliable computing systems from unreliable components, we formalize the problem of reliable storage of quantum information using noisy components. We introduce the notion of stable quantum memories and define the storage rate as the ratio of the number of logical qubits to the total number of physical qubits as well as the circuit complexity of the decoder, which includes both quantum gates and measurements. We demonstrate that a strictly positive storage rate can be achieved by constructing a quantum memory system with quantum expander codes. Moreover, by reducing the reliable storage problem to reliable quantum communication, we provide upper bounds on the achievable storage capacity. In the case of physical qubits corrupted by noise satisfying hypercontractivity conditions, we provide a tighter upper bound on storage capacity using an entropy dissipation argument. Furthermore, observing that the time complexity of the decoder scales nontrivially with the number of physical qubits, achieving asymptotic rates may not be possible due to the induced dependence of the noise on the number of physical qubits. In this constrained nonasymptotic setting, we derive upper bounds on storage capacity using finite blocklength communication bounds. Finally, we numerically analyze the gap between upper and lower bounds in both asymptotic and nonasymptotic cases, and provide suggestions to tighten the gap.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"49 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262767","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 : 2024-09-18DOI: 10.1103/physreva.110.033320
Jan Major, Joachim Brand
Solitonlike localized wave solutions in a two-dimensional Fermi superfluid are studied by solving the Bogoliubov–de Gennes equations in the BCS regime of weak pairing interactions. The dispersion relations of these solitons are found to exhibit a peculiar swallow-tail shape, with cusps and multiple branches. The effective mass of the solitons is found to diverge and change sign at the cusp. This behavior is in contrast to the smooth dispersion relations and negative effective masses of solitons in the three-dimensional Fermi superfluid. The swallow-tail dispersion relations are shown to be a consequence of counterflow of the superfluid and sign-changing contributions to the superfluid current from different transverse momenta in the Bogoliubov–de Gennes formalism. The results are relevant for the understanding of solitonic excitations in two-dimensional Fermi superfluids, such as ultracold atomic gases and high-temperature superconductors.
{"title":"Swallow-tail dispersions of moving solitons in a two-dimensional fermionic superfluid","authors":"Jan Major, Joachim Brand","doi":"10.1103/physreva.110.033320","DOIUrl":"https://doi.org/10.1103/physreva.110.033320","url":null,"abstract":"Solitonlike localized wave solutions in a two-dimensional Fermi superfluid are studied by solving the Bogoliubov–de Gennes equations in the BCS regime of weak pairing interactions. The dispersion relations of these solitons are found to exhibit a peculiar swallow-tail shape, with cusps and multiple branches. The effective mass of the solitons is found to diverge and change sign at the cusp. This behavior is in contrast to the smooth dispersion relations and negative effective masses of solitons in the three-dimensional Fermi superfluid. The swallow-tail dispersion relations are shown to be a consequence of counterflow of the superfluid and sign-changing contributions to the superfluid current from different transverse momenta in the Bogoliubov–de Gennes formalism. The results are relevant for the understanding of solitonic excitations in two-dimensional Fermi superfluids, such as ultracold atomic gases and high-temperature superconductors.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"48 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262775","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 : 2024-09-18DOI: 10.1103/physreva.110.033519
S. Suzuki, A. Gerakis, K. Hara
Single-shot coherent Rayleigh-Brillouin scattering (CRBS) is modeled using direct simulation Monte Carlo (DSMC). In CRBS, an optical lattice generated by the interference of two pump lasers traps the neutral particles via the dipole force. The gradient of refractive index due to the trapped particles of the gaseous media leads to coherent scattering of a probe beam, resulting in the CRBS signal. Additionally, using a chirped laser beam, CRBS signals can be obtained in a single laser shot, shortening the measurement time of the gas flow (on the order of 100 ns). The DSMC results of single-shot CRBS assuming Maxwellian velocity distribution functions (VDFs) show good agreement with experimental data, including argon, carbon dioxide, and xenon, for different gas pressures. One of the key observations obtained from the present simulations is that the CRBS signals become asymmetric when using a fast chirp rate due to finite time for collisionless trapping and collisional thermalization.
{"title":"Effects of the chirp rate on single-shot coherent Rayleigh-Brillouin scattering","authors":"S. Suzuki, A. Gerakis, K. Hara","doi":"10.1103/physreva.110.033519","DOIUrl":"https://doi.org/10.1103/physreva.110.033519","url":null,"abstract":"Single-shot coherent Rayleigh-Brillouin scattering (CRBS) is modeled using direct simulation Monte Carlo (DSMC). In CRBS, an optical lattice generated by the interference of two pump lasers traps the neutral particles via the dipole force. The gradient of refractive index due to the trapped particles of the gaseous media leads to coherent scattering of a probe beam, resulting in the CRBS signal. Additionally, using a chirped laser beam, CRBS signals can be obtained in a single laser shot, shortening the measurement time of the gas flow (on the order of 100 ns). The DSMC results of single-shot CRBS assuming Maxwellian velocity distribution functions (VDFs) show good agreement with experimental data, including argon, carbon dioxide, and xenon, for different gas pressures. One of the key observations obtained from the present simulations is that the CRBS signals become asymmetric when using a fast chirp rate due to finite time for collisionless trapping and collisional thermalization.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"4 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262776","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 : 2024-09-18DOI: 10.1103/physreva.110.032815
V. K. Ivanov, S. S. Baturin, D. A. Glazov, A. V. Volotka
The finite-basis-set method is commonly used to calculate atomic spectra, including quantum electrodynamics contributions such as bound-electron self-energy. Still, it remains problematic and underexplored for vacuum-polarization calculations. We fill this gap by trying this approach in its application to the calculation of the vacuum-polarization charge density and the Wichmann-Kroll correction to the electron binding energy in a hydrogen-like ion. We study the convergence of the method with different types and sizes of basis sets. We cross-check our results for the Wichmann-Kroll correction by direct integration of the Green's function. As a relevant example, we consider several heavy hydrogen-like ions and evaluate the vacuum polarization correction for and electron orbitals.
有限基础集方法常用于计算原子光谱，包括量子电动力学贡献，如束缚电子自能。然而，这种方法在真空极化计算中仍然存在问题，而且探索不足。我们尝试将这种方法应用于计算真空极化电荷密度和类氢离子中电子结合能的 Wichmann-Kroll 校正，从而填补了这一空白。我们研究了该方法在使用不同类型和大小的基集时的收敛性。我们通过对格林函数的直接积分来交叉检验 Wichmann-Kroll 校正的结果。作为一个相关的例子，我们考虑了几种重的类氢离子，并评估了 S 和 P 电子轨道的真空极化修正。
{"title":"Vacuum-polarization Wichmann-Kroll correction in the finite-basis-set approach","authors":"V. K. Ivanov, S. S. Baturin, D. A. Glazov, A. V. Volotka","doi":"10.1103/physreva.110.032815","DOIUrl":"https://doi.org/10.1103/physreva.110.032815","url":null,"abstract":"The finite-basis-set method is commonly used to calculate atomic spectra, including quantum electrodynamics contributions such as bound-electron self-energy. Still, it remains problematic and underexplored for vacuum-polarization calculations. We fill this gap by trying this approach in its application to the calculation of the vacuum-polarization charge density and the Wichmann-Kroll correction to the electron binding energy in a hydrogen-like ion. We study the convergence of the method with different types and sizes of basis sets. We cross-check our results for the Wichmann-Kroll correction by direct integration of the Green's function. As a relevant example, we consider several heavy hydrogen-like ions and evaluate the vacuum polarization correction for <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>S</mi></math> and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>P</mi></math> electron orbitals.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"19 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262774","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 : 2024-09-17DOI: 10.1103/physreva.110.032812
Jungwoo Choi, Eunhwi Lee, Dahyun Yum, Kyungwon An, Junki Kim
We report the direct measurement of isotope shifts of the barium 413-nm electric quadrupole transition, which is utilized for efficient barium ion trapping via photoionization using a single coherent light source. The measured isotope shifts relative to are , , , and for isotopes with atomic numbers 137, 136, 135, and 134, respectively. We verify the measured isotopes with King plot analysis and compare the result with the formerly known shifts inferred from previous studies on neighboring transitions. The results can be used for efficient isotope selective loading of low-abundant barium ions, while careful suppression of line broadening is required for successful isotopic selectivity.
{"title":"Direct measurement of isotope shifts in the barium 6s2 S01–5d6p D1o3 transition","authors":"Jungwoo Choi, Eunhwi Lee, Dahyun Yum, Kyungwon An, Junki Kim","doi":"10.1103/physreva.110.032812","DOIUrl":"https://doi.org/10.1103/physreva.110.032812","url":null,"abstract":"We report the direct measurement of isotope shifts of the barium <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msup><mrow><mi>s</mi></mrow><mn>2</mn></msup></mrow></math> <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mmultiscripts><mi>S</mi><mn>0</mn><none></none><mprescripts></mprescripts><none></none><mn>1</mn></mmultiscripts><mtext>–</mtext><mn>5</mn><mi>d</mi><mn>6</mn><mi>p</mi><mmultiscripts><mi>D</mi><mn>1</mn><mi mathvariant=\"normal\">o</mi><mprescripts></mprescripts><none></none><mn>3</mn></mmultiscripts></mrow></math> 413-nm electric quadrupole transition, which is utilized for efficient barium ion trapping via photoionization using a single coherent light source. The measured isotope shifts relative to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mmultiscripts><mi>Ba</mi><mprescripts></mprescripts><none></none><mn>138</mn></mmultiscripts></math> are <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>392.9</mn><mo>±</mo><mn>0.9</mn><mspace width=\"0.16em\"></mspace><mi>MHz</mi></mrow></math>, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>178.1</mn><mo>±</mo><mn>0.8</mn><mspace width=\"0.16em\"></mspace><mi>MHz</mi></mrow></math>, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>401.4</mn><mo>±</mo><mn>1.2</mn><mspace width=\"0.16em\"></mspace><mi>MHz</mi></mrow></math>, and <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>124.3</mn><mo>±</mo><mn>1.3</mn><mspace width=\"0.16em\"></mspace><mi>MHz</mi></mrow></math> for isotopes with atomic numbers 137, 136, 135, and 134, respectively. We verify the measured isotopes with King plot analysis and compare the result with the formerly known shifts inferred from previous studies on neighboring transitions. The results can be used for efficient isotope selective loading of low-abundant barium ions, while careful suppression of line broadening is required for successful isotopic selectivity.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"20 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262770","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 : 2024-09-17DOI: 10.1103/physreva.110.033518
K. S. Netherwood, H. K. Riley, E. A. Muljarov
Exceptional points (EPs) in open optical systems are rigorously studied using the resonant-state expansion (RSE). A spherical resonator, specifically a homogeneous dielectric sphere in a vacuum, perturbed by two pointlike defects which break the spherical symmetry and bring the optical modes to EPs, is used as a worked example. The RSE is a nonperturbative approach encoding the information about an open optical system in matrix form in a rigorous way, and thus offering a suitable tool for studying its EPs. These are simultaneous degeneracies of the eigenvalues and corresponding eigenfunctions of the system, which are rigorously described by the RSE and illustrated for perturbed whispering-gallery modes (WGMs). An exceptional arc, which is a line of adjacent EPs, is obtained analytically for perturbed dipolar WGMs. Perturbation of high-quality WGMs with large angular momentum and their EPs are found by reducing the RSE equation to a two-state problem by means of an orthogonal transformation of a large RSE matrix. WGM pairs have opposite chirality in spherically symmetric systems and equal chirality at EPs. This chirality at EPs can be observed in circular dichroism measurements, as it manifested itself in a squared-Lorentzian part of the optical spectra, which we demonstrate here analytically and numerically in the Purcell enhancement factor for the perturbed dipolar WGMs.
利用共振态扩展（RSE）对开放光学系统中的异常点（EPs）进行了严格研究。我们以一个球形谐振器（具体来说是真空中的均质介质球）为工作实例，该谐振器受到两个点状缺陷的扰动，这两个点状缺陷打破了球形对称性，使光学模式出现了异常点。RSE 是一种非扰动方法，以矩阵形式严格编码开放光学系统的信息，从而为研究其 EPs 提供了合适的工具。这些是系统特征值和相应特征函数的同步退化，RSE 对其进行了严格描述，并对扰动耳语画廊模式（WGM）进行了说明。对于扰动双极性 WGM，可以通过分析得到一条特殊弧线，即相邻 EP 的连线。通过对大型 RSE 矩阵进行正交变换，将 RSE 方程简化为双态问题，从而找到了具有大角动量的高质量 WGM 的扰动及其 EP。在球对称系统中，WGM 对具有相反的手性，而在 EP 处则具有相等的手性。这种在 EP 处的手性可以在圆二色性测量中观察到，因为它表现在光学光谱的方形-洛伦兹部分，我们在此通过分析和数值方法证明了扰动双极 WGM 的珀塞尔增强因子。
{"title":"Exceptional points in perturbed dielectric spheres: A resonant-state expansion study","authors":"K. S. Netherwood, H. K. Riley, E. A. Muljarov","doi":"10.1103/physreva.110.033518","DOIUrl":"https://doi.org/10.1103/physreva.110.033518","url":null,"abstract":"Exceptional points (EPs) in open optical systems are rigorously studied using the resonant-state expansion (RSE). A spherical resonator, specifically a homogeneous dielectric sphere in a vacuum, perturbed by two pointlike defects which break the spherical symmetry and bring the optical modes to EPs, is used as a worked example. The RSE is a nonperturbative approach encoding the information about an open optical system in matrix form in a rigorous way, and thus offering a suitable tool for studying its EPs. These are simultaneous degeneracies of the eigenvalues and corresponding eigenfunctions of the system, which are rigorously described by the RSE and illustrated for perturbed whispering-gallery modes (WGMs). An exceptional arc, which is a line of adjacent EPs, is obtained analytically for perturbed dipolar WGMs. Perturbation of high-quality WGMs with large angular momentum and their EPs are found by reducing the RSE equation to a two-state problem by means of an orthogonal transformation of a large RSE matrix. WGM pairs have opposite chirality in spherically symmetric systems and equal chirality at EPs. This chirality at EPs can be observed in circular dichroism measurements, as it manifested itself in a squared-Lorentzian part of the optical spectra, which we demonstrate here analytically and numerically in the Purcell enhancement factor for the perturbed dipolar WGMs.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"27 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262927","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 : 2024-09-17DOI: 10.1103/physreva.110.032214
R. A. Caetano, R. M. Angelo
Based on (i) the physical principle of local causality and (ii) a certain notion of elements of reality, Einstein, Podolsky, and Rosen put forward an argument showing that physical instances may exist in which two noncommuting observables can be joint elements of the physical reality. Here, we introduce a new criterion of joint reality. We demonstrate that according to this criterion, quantum mechanics generally prevents noncommuting observables from having joint elements of reality. In addition, we introduce a measure to quantify the extent to which the criterion is violated and explore the implications of such a measure in connection with incompatibility and correlations. Our findings suggest new manners of interpreting quantum phenomena.
{"title":"Quantum violations of joint reality","authors":"R. A. Caetano, R. M. Angelo","doi":"10.1103/physreva.110.032214","DOIUrl":"https://doi.org/10.1103/physreva.110.032214","url":null,"abstract":"Based on (i) the physical principle of local causality and (ii) a certain notion of elements of reality, Einstein, Podolsky, and Rosen put forward an argument showing that physical instances may exist in which two noncommuting observables can be joint elements of the physical reality. Here, we introduce a new criterion of joint reality. We demonstrate that according to this criterion, quantum mechanics generally prevents noncommuting observables from having joint elements of reality. In addition, we introduce a measure to quantify the extent to which the criterion is violated and explore the implications of such a measure in connection with incompatibility and correlations. Our findings suggest new manners of interpreting quantum phenomena.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"134 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262923","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 : 2024-09-17DOI: 10.1103/physreva.110.032813
M. O. Araújo, J. C. de Aquino Carvalho, Ph. W. Courteille, A. Laliotis
Cooperative effects such as super- and subradiance can be observed in the fluorescence emitted by a system of atoms in vacuum after interaction with a laser beam. In the vicinity of a dielectric or metallic surface, Casimir-Polder effects can modify collective atomic frequency shifts and decay rates. In this work, we study cooperative fluorescent emission next to resonant surfaces using the coupled-dipole model. We show that cooperative effects, expected in free space, are absent when the atoms are close to a surface whose polariton resonances coincide with the dominant atomic dipole coupling. In this case, cooperative effects are overshadowed by the very fast decay of the atomic fluorescence into surface modes. We illustrate our formalism and our results by considering a line of cesium atoms in front of a sapphire surface. Finally, we propose the study of cesium atoms in front of a resonant metasurface as the most promising scenario for experimentally demonstrating the results of our study.
由 N 个原子组成的系统在真空中与激光束相互作用后发出的荧光中可以观察到超辐射和亚辐射等合作效应。在电介质或金属表面附近，卡西米尔-波德尔效应会改变原子的集体频移和衰减率。在这项工作中，我们利用耦合偶极子模型研究了共振表面附近的协同荧光发射。我们的研究表明，当原子靠近极化子共振与主要原子偶极子耦合重合的表面时，自由空间中预期的合作效应并不存在。在这种情况下，原子荧光与表面模式的快速衰减掩盖了合作效应。我们通过考虑蓝宝石表面前的一条铯 6D3/2 原子线来说明我们的形式主义和结果。最后，我们建议对共振元表面前的铯 6P3/2 原子进行研究，这是实验证明我们研究结果的最有希望的方案。
{"title":"Cooperative atomic emission from a line of atoms interacting with a resonant plane surface","authors":"M. O. Araújo, J. C. de Aquino Carvalho, Ph. W. Courteille, A. Laliotis","doi":"10.1103/physreva.110.032813","DOIUrl":"https://doi.org/10.1103/physreva.110.032813","url":null,"abstract":"Cooperative effects such as super- and subradiance can be observed in the fluorescence emitted by a system of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>N</mi></math> atoms in vacuum after interaction with a laser beam. In the vicinity of a dielectric or metallic surface, Casimir-Polder effects can modify collective atomic frequency shifts and decay rates. In this work, we study cooperative fluorescent emission next to resonant surfaces using the coupled-dipole model. We show that cooperative effects, expected in free space, are absent when the atoms are close to a surface whose polariton resonances coincide with the dominant atomic dipole coupling. In this case, cooperative effects are overshadowed by the very fast decay of the atomic fluorescence into surface modes. We illustrate our formalism and our results by considering a line of cesium <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>D</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> atoms in front of a sapphire surface. Finally, we propose the study of cesium <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>6</mn><msub><mi>P</mi><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msub></mrow></math> atoms in front of a resonant metasurface as the most promising scenario for experimentally demonstrating the results of our study.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"118 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262926","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 : 2024-09-17DOI: 10.1103/physreva.110.032421
Yanjun Ji, Kathrin F. Koenig, Ilia Polian
This paper presents strategies to improve the performance of digitized counterdiabatic quantum optimization algorithms by cooptimizing gate sequences, algorithm parameters, and qubit mapping. Demonstrations on real hardware validate the effectiveness of these strategies, leveraging both algorithmic and hardware advantages. Specifically, our approach achieves an average increase in approximation ratio of without error mitigation and 84.8% with error mitigation compared to Qiskit and Tket on IBM quantum processors. These findings provide valuable insights into the codesign of algorithm implementation, tailored to optimize qubit mapping and algorithm parameters, with broader implications for enhancing algorithm performance on near-term quantum devices.
本文介绍了通过协同优化门序列、算法参数和量子位映射来提高数字化逆绝热量子优化算法性能的策略。利用算法和硬件优势，在实际硬件上的演示验证了这些策略的有效性。具体地说，与 IBM 量子处理器上的 Qiskit 和 Tket 相比，我们的方法在没有错误缓解的情况下，近似率平均提高了 4.49 倍；在有错误缓解的情况下，近似率平均提高了 84.8%。这些发现为算法实现的代码设计提供了宝贵的见解，为优化量子比特映射和算法参数量身定制，对提高近期量子设备上的算法性能具有更广泛的意义。
{"title":"Improving the performance of digitized counterdiabatic quantum optimization via algorithm-oriented qubit mapping","authors":"Yanjun Ji, Kathrin F. Koenig, Ilia Polian","doi":"10.1103/physreva.110.032421","DOIUrl":"https://doi.org/10.1103/physreva.110.032421","url":null,"abstract":"This paper presents strategies to improve the performance of digitized counterdiabatic quantum optimization algorithms by cooptimizing gate sequences, algorithm parameters, and qubit mapping. Demonstrations on real hardware validate the effectiveness of these strategies, leveraging both algorithmic and hardware advantages. Specifically, our approach achieves an average increase in approximation ratio of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>4.49</mn><mo>×</mo></mrow></math> without error mitigation and 84.8% with error mitigation compared to Qiskit and Tket on IBM quantum processors. These findings provide valuable insights into the codesign of algorithm implementation, tailored to optimize qubit mapping and algorithm parameters, with broader implications for enhancing algorithm performance on near-term quantum devices.","PeriodicalId":20146,"journal":{"name":"Physical Review A","volume":"241 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142262925","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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