Pub Date : 2024-09-16DOI: 10.1088/1361-6455/ad76ef
Reinhold Blümel, Andrii Maksymov and Ming Li
Realistic fault-tolerant quantum computing at reasonable overhead requires two-qubit gates with the highest possible fidelity. Typically, an infidelity of is recommended in the literature. Focusing on the phase-sensitive architecture used in laboratories and by commercial companies to implement quantum computers, we show that even under noise-free, ideal conditions, neglecting the carrier term and linearizing the Lamb–Dicke term in the Hamiltonian used for control-pulse construction for generating Mølmer–Sørensen XX gates based on the Raman scheme are not justified if the goal is an infidelity target of . We obtain these results with a gate simulator code that, in addition to the computational space, explicitly takes the most relevant part of the phonon space into account. With the help of a Magnus expansion carried to the third order, keeping terms up to the fourth order in the Lamb–Dicke parameters, we identify the leading sources of coherent errors, which we show can be eliminated by adding a single linear equation to the phase-space closure conditions and subsequently adjusting the amplitude of the control pulse (calibration). This way, we obtain XX gates with infidelities .
要想以合理的开销实现容错量子计算，就需要尽可能高保真的双量子比特门。通常，文献中推荐的保真度为。我们重点研究了实验室和商业公司用于实现量子计算机的相敏架构，结果表明，即使在无噪声的理想条件下，如果目标是保真度达到......，那么忽略载流子项和线性化基于拉曼方案生成默尔默-索伦森 XX 门的控制脉冲构建所用哈密顿中的 Lamb-Dicke 项都是不合理的。 我们利用门模拟器代码获得了这些结果，该代码除了计算空间外，还明确考虑了声子空间中最相关的部分。在马格努斯三阶扩展的帮助下，我们确定了相干误差的主要来源，并在相空间闭合条件中添加了一个线性方程，随后调整了控制脉冲的振幅（校准），从而消除了相干误差。这样，我们就可以得到具有不可靠度的 XX 门。
{"title":"Toward a Mølmer Sørensen gate with .9999 fidelity","authors":"Reinhold Blümel, Andrii Maksymov and Ming Li","doi":"10.1088/1361-6455/ad76ef","DOIUrl":"https://doi.org/10.1088/1361-6455/ad76ef","url":null,"abstract":"Realistic fault-tolerant quantum computing at reasonable overhead requires two-qubit gates with the highest possible fidelity. Typically, an infidelity of is recommended in the literature. Focusing on the phase-sensitive architecture used in laboratories and by commercial companies to implement quantum computers, we show that even under noise-free, ideal conditions, neglecting the carrier term and linearizing the Lamb–Dicke term in the Hamiltonian used for control-pulse construction for generating Mølmer–Sørensen XX gates based on the Raman scheme are not justified if the goal is an infidelity target of . We obtain these results with a gate simulator code that, in addition to the computational space, explicitly takes the most relevant part of the phonon space into account. With the help of a Magnus expansion carried to the third order, keeping terms up to the fourth order in the Lamb–Dicke parameters, we identify the leading sources of coherent errors, which we show can be eliminated by adding a single linear equation to the phase-space closure conditions and subsequently adjusting the amplitude of the control pulse (calibration). This way, we obtain XX gates with infidelities .","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"3 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-16DOI: 10.1088/1361-6455/ad6b62
Jérémy R Rouxel, Riccardo Mincigrucci, Danny Fainozzi and Claudio Masciovecchio
Measuring natural circular dichroism in the x-ray regime to extract stereochemical information from chiral molecules in solution remains a challenge. This is primarily due to technical limitations of the existing synchrotron sources, which hinder access to measurements of local chirality by exploiting core hole electronic transitions. In response to this challenge, we propose an alternative approach: utilizing XFEL-based cross-polarization x-ray transient grating (XTG). This method provides an indirect means to measure x-ray circular dichroism (XCD). Notably, our findings reveal that the signal emerges only once the excited cores have undergone dephasing through relaxation. XTG is now routinely measured in the XUV regime and has recently been made available for hard x-rays. Free electron lasers now offer polarization controls, and XTG can be extended to various polarization states for the two pump beams, making XCD measured by XTG feasible with the current state-of-the-art technology.
在 X 射线系统中测量自然圆二色性以提取溶液中手性分子的立体化学信息仍然是一项挑战。这主要是由于现有同步辐射源的技术限制，阻碍了通过利用核心空穴电子跃迁测量局部手性。为了应对这一挑战，我们提出了另一种方法：利用基于 XFEL 的交叉偏振 X 射线瞬态光栅 (XTG)。这种方法提供了一种间接测量 X 射线圆二色性（XCD）的方法。值得注意的是，我们的研究结果表明，只有在受激核心经过弛豫去相之后，信号才会出现。XTG 现已在 XUV 系统中进行常规测量，最近还可用于硬 X 射线。自由电子激光器现在提供偏振控制，XTG 可以扩展到两个泵浦光束的各种偏振态，这使得用 XTG 测量 XCD 在当前最先进的技术条件下变得可行。
{"title":"X-ray circular dichroism measured by cross-polarization x-ray transient grating","authors":"Jérémy R Rouxel, Riccardo Mincigrucci, Danny Fainozzi and Claudio Masciovecchio","doi":"10.1088/1361-6455/ad6b62","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b62","url":null,"abstract":"Measuring natural circular dichroism in the x-ray regime to extract stereochemical information from chiral molecules in solution remains a challenge. This is primarily due to technical limitations of the existing synchrotron sources, which hinder access to measurements of local chirality by exploiting core hole electronic transitions. In response to this challenge, we propose an alternative approach: utilizing XFEL-based cross-polarization x-ray transient grating (XTG). This method provides an indirect means to measure x-ray circular dichroism (XCD). Notably, our findings reveal that the signal emerges only once the excited cores have undergone dephasing through relaxation. XTG is now routinely measured in the XUV regime and has recently been made available for hard x-rays. Free electron lasers now offer polarization controls, and XTG can be extended to various polarization states for the two pump beams, making XCD measured by XTG feasible with the current state-of-the-art technology.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"14 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-15DOI: 10.1088/1361-6455/ad7552
Caelan Brooks and Kunal K Das
We examine the spectrum and quantum states of small lattices with cylindrical and toroidal topology subject to a scalar gauge potential that introduces a position dependent phase in the inter-site coupling. Equivalency of gauges assumed in infinite lattices is generally lost due to the periodic boundary conditions, and conditions that restore it are identified. We trace the impact of various system parameters including gauge choice, boundary conditions and inter-site coupling strengths, and an additional axial field. We find gauge dependent appearance of avoided crossings and persistent degeneracies, and we show their impact on the associated eigenstates. Smaller lattices develop prominent gaps in spectral lines associated with edge states, which are suppressed in the thermodynamic limit. Toroidal lattices have counterparts of most of the features observed in cylindrical lattices, but notably they display a transition from localization to delocalization determined by the relation between the field parameter and the number of lattice sites.
{"title":"Quantum states and spectra of small cylindrical and toroidal lattices","authors":"Caelan Brooks and Kunal K Das","doi":"10.1088/1361-6455/ad7552","DOIUrl":"https://doi.org/10.1088/1361-6455/ad7552","url":null,"abstract":"We examine the spectrum and quantum states of small lattices with cylindrical and toroidal topology subject to a scalar gauge potential that introduces a position dependent phase in the inter-site coupling. Equivalency of gauges assumed in infinite lattices is generally lost due to the periodic boundary conditions, and conditions that restore it are identified. We trace the impact of various system parameters including gauge choice, boundary conditions and inter-site coupling strengths, and an additional axial field. We find gauge dependent appearance of avoided crossings and persistent degeneracies, and we show their impact on the associated eigenstates. Smaller lattices develop prominent gaps in spectral lines associated with edge states, which are suppressed in the thermodynamic limit. Toroidal lattices have counterparts of most of the features observed in cylindrical lattices, but notably they display a transition from localization to delocalization determined by the relation between the field parameter and the number of lattice sites.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"13 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-10DOI: 10.1088/1361-6455/ad76f0
C L Vaillant, M P A Jones and R M Potvliege
Newly calculated multichannel quantum defect theory parameters and channel fractions are presented for the singlet and triplet S, P and D series and singlet F series of strontium. These results correct those reported in Vaillant et al (2014 J. Phys. B: At. Mol. Opt. Phys.47 155001).
新计算的多通道量子缺陷理论参数和通道分数用于锶的单重和三重 S、P 和 D 系列以及单重 F 系列。这些结果修正了 Vaillant 等人（2014 J. Phys. B: At. Mol. Opt. Phys.47 155001）报告的结果。
{"title":"Addendum: Multichannel quantum defect theory of strontium bound Rydberg states (2014 J. Phys. B: At. Mol. Opt. Phys. 47 155001)","authors":"C L Vaillant, M P A Jones and R M Potvliege","doi":"10.1088/1361-6455/ad76f0","DOIUrl":"https://doi.org/10.1088/1361-6455/ad76f0","url":null,"abstract":"Newly calculated multichannel quantum defect theory parameters and channel fractions are presented for the singlet and triplet S, P and D series and singlet F series of strontium. These results correct those reported in Vaillant et al (2014 J. Phys. B: At. Mol. Opt. Phys.47 155001).","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"3 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-09DOI: 10.1088/1361-6455/ad75f6
I I Fabrikant and H B Ambalampitiya
We study the process of laser-assisted radiative recombination of an electron with a proton in a cold hydrogen plasma employing the semiclassical Kramers’ approach which involves calculation of classical trajectories in combined laser and Coulomb fields and the use of the correspondence principle. Due to the Coulomb focusing effect, recombination is the most effective when the initial electron momentum is parallel to the laser polarization. Orders of magnitude enhancement of the cross section, as compared to the laser-free case, is observed in this case. With increasing angle between the electron momentum and polarization, the recombination cross section drops. However, even after averaging over Maxwellian velocity distribution we obtain a substantial enhancement of the recombination rate constant, as compared to the zero-field case. For the field intensities in the range 30–350 MW cm−2, the enhancement occurs in the region of the radiation wavelength from 5 to 20 µm and for the plasma temperature from 20 to 300 K.
{"title":"Laser-assisted radiative recombination in a cold hydrogen plasma","authors":"I I Fabrikant and H B Ambalampitiya","doi":"10.1088/1361-6455/ad75f6","DOIUrl":"https://doi.org/10.1088/1361-6455/ad75f6","url":null,"abstract":"We study the process of laser-assisted radiative recombination of an electron with a proton in a cold hydrogen plasma employing the semiclassical Kramers’ approach which involves calculation of classical trajectories in combined laser and Coulomb fields and the use of the correspondence principle. Due to the Coulomb focusing effect, recombination is the most effective when the initial electron momentum is parallel to the laser polarization. Orders of magnitude enhancement of the cross section, as compared to the laser-free case, is observed in this case. With increasing angle between the electron momentum and polarization, the recombination cross section drops. However, even after averaging over Maxwellian velocity distribution we obtain a substantial enhancement of the recombination rate constant, as compared to the zero-field case. For the field intensities in the range 30–350 MW cm−2, the enhancement occurs in the region of the radiation wavelength from 5 to 20 µm and for the plasma temperature from 20 to 300 K.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"34-35 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-09DOI: 10.1088/1361-6455/ad717b
A Hosier, 0000-0001-6675-8509Dipti3, S A Blundell, R Silwal, A Lapierre, J D Gillaspy, G Gwinner, J N Tan, A A Kwiatkowski, Y Wang, H Staiger, A C C Villari, Yu Ralchenko, E Takacs
We describe a novel technique to determine absolute nuclear radii of high-Z nuclides. Utilizing accurate theoretical atomic structure calculations together with precise measurements of extreme ultraviolet transitions in highly charged ions this method allows for precise determinations of absolute nuclear charge radii based upon the well-known nuclear radii of their neighboring elements. This method can work for elements without stable isotopes, and its accuracy may be competitive with current methods (electron scattering and muonic x-ray spectroscopy).
我们描述了一种测定高Z 核素绝对核半径的新技术。利用精确的原子结构理论计算和对高电荷离子的极紫外跃迁的精确测量，这种方法可以根据众所周知的邻近元素的核半径来精确测定绝对核电荷半径。这种方法适用于没有稳定同位素的元素，其准确性可与目前的方法（电子散射和μ介子 X 射线光谱法）相媲美。
{"title":"Absolute nuclear charge radius by Na-like spectral line separation in high-Z elements","authors":"A Hosier, 0000-0001-6675-8509Dipti3, S A Blundell, R Silwal, A Lapierre, J D Gillaspy, G Gwinner, J N Tan, A A Kwiatkowski, Y Wang, H Staiger, A C C Villari, Yu Ralchenko, E Takacs","doi":"10.1088/1361-6455/ad717b","DOIUrl":"https://doi.org/10.1088/1361-6455/ad717b","url":null,"abstract":"We describe a novel technique to determine absolute nuclear radii of high-<italic toggle=\"yes\">Z</italic> nuclides. Utilizing accurate theoretical atomic structure calculations together with precise measurements of extreme ultraviolet transitions in highly charged ions this method allows for precise determinations of absolute nuclear charge radii based upon the well-known nuclear radii of their neighboring elements. This method can work for elements without stable isotopes, and its accuracy may be competitive with current methods (electron scattering and muonic x-ray spectroscopy).","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"26 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-06DOI: 10.1088/1361-6455/ad7551
Ichiro Inoue, Beata Ziaja
In this perspective article we propose and discuss a possible technique of in-depth material processing based on undersurface focusing of intense x-ray pulses. Currently, x-ray free-electron lasers can produce such intense x-ray pulses with femtosecond pulse durations, reaching intensities sufficiently high to cause ultrafast melting of a material after a single laser shot. Here, on the example of silicon crystal we will demonstrate that with a proper choice of pulse parameters and focusing parameters, the already existing nanofocusing setup has a capability to focus hard x rays down to several hundreds micrometers below the material surface. This can trigger the required structural modification in the focal point, without damaging the material above. Potential applications of the new technique are discussed.
在这篇展望文章中，我们提出并讨论了一种基于强 X 射线脉冲表面下聚焦的材料深度加工技术。目前，X 射线自由电子激光器可以产生飞秒脉冲持续时间的强 X 射线脉冲，其强度足以在一次激光发射后导致材料超快熔化。在这里，我们将以硅晶体为例，证明只要正确选择脉冲参数和聚焦参数，现有的纳米聚焦装置就有能力将硬 X 射线聚焦到材料表面以下数百微米处。这样就能在焦点处引发所需的结构改变，而不会损坏上面的材料。本文讨论了这项新技术的潜在应用。
{"title":"Perspective for in-volume machining of solid materials by undersurface focusing of x-ray pulses","authors":"Ichiro Inoue, Beata Ziaja","doi":"10.1088/1361-6455/ad7551","DOIUrl":"https://doi.org/10.1088/1361-6455/ad7551","url":null,"abstract":"In this perspective article we propose and discuss a possible technique of in-depth material processing based on undersurface focusing of intense x-ray pulses. Currently, x-ray free-electron lasers can produce such intense x-ray pulses with femtosecond pulse durations, reaching intensities sufficiently high to cause ultrafast melting of a material after a single laser shot. Here, on the example of silicon crystal we will demonstrate that with a proper choice of pulse parameters and focusing parameters, the already existing nanofocusing setup has a capability to focus hard x rays down to several hundreds micrometers below the material surface. This can trigger the required structural modification in the focal point, without damaging the material above. Potential applications of the new technique are discussed.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"2 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-06DOI: 10.1088/1361-6455/ad7431
Kareem Hegazy, Phil Bucksbaum, Martin Centurion, James Cryan, Renkai Li, Ming-Fu Lin, Bryan Moore, Pedro Nunes, Xiaozhe Shen, Stephen Weathersby, Jie Yang, Xijie Wang, Thomas Wolf
As the simplest nitroaromatic compound, nitrobenzene is an interesting model system to explore the rich photochemistry of nitroaromatic compounds. Previous investigations of nitrobenzene’s photochemical dynamics have probed structural and electronic properties. These investigations paint, at times, a convoluted and sometimes contradictory description of the photochemical landscape. We investigate the ultrafast dynamics of nitrobenzene triggered by photoexcitation at 267 nm for the first time using a structural probe with femtosecond time resolution. Our probe complements previous measurements of nitrobenzene’s electronic structure evolution and aids in determining the photochemical dynamics with less ambiguity. We employ megaelectronvolt ultrafast electron diffraction to follow nitrobenzene’s structural evolution within the first 5 ps after photoexcitation. We observe ground state recovery within 160±60 fs through nonadiabatic dynamics. Based on comparisons of the experimental signal with molecular dynamics simulations, we exclude a significant population of the triplet manifold. Furthermore, we do not observe fragmentation of nitrobenzene within the investigated time window, which indicates that previously observed photofragmentation reactions take place in the vibrationally ‘hot’ ground state on timescales considerably beyond 5 ps.
{"title":"Tracking dissociation pathways of nitrobenzene via mega-electron-volt ultrafast electron diffraction","authors":"Kareem Hegazy, Phil Bucksbaum, Martin Centurion, James Cryan, Renkai Li, Ming-Fu Lin, Bryan Moore, Pedro Nunes, Xiaozhe Shen, Stephen Weathersby, Jie Yang, Xijie Wang, Thomas Wolf","doi":"10.1088/1361-6455/ad7431","DOIUrl":"https://doi.org/10.1088/1361-6455/ad7431","url":null,"abstract":"As the simplest nitroaromatic compound, nitrobenzene is an interesting model system to explore the rich photochemistry of nitroaromatic compounds. Previous investigations of nitrobenzene’s photochemical dynamics have probed structural and electronic properties. These investigations paint, at times, a convoluted and sometimes contradictory description of the photochemical landscape. We investigate the ultrafast dynamics of nitrobenzene triggered by photoexcitation at 267 nm for the first time using a structural probe with femtosecond time resolution. Our probe complements previous measurements of nitrobenzene’s electronic structure evolution and aids in determining the photochemical dynamics with less ambiguity. We employ megaelectronvolt ultrafast electron diffraction to follow nitrobenzene’s structural evolution within the first 5 ps after photoexcitation. We observe ground state recovery within <inline-formula>\u0000<tex-math><?CDATA $160 pm 60$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mn>160</mml:mn><mml:mo>±</mml:mo><mml:mn>60</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"bad7431ieqn1.gif\"></inline-graphic></inline-formula> fs through nonadiabatic dynamics. Based on comparisons of the experimental signal with molecular dynamics simulations, we exclude a significant population of the triplet manifold. Furthermore, we do not observe fragmentation of nitrobenzene within the investigated time window, which indicates that previously observed photofragmentation reactions take place in the vibrationally ‘hot’ ground state on timescales considerably beyond 5 ps.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"161 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-09-06DOI: 10.1088/1361-6455/ad7458
T Vibel, M B Christensen, R M F Andersen, L N Stokholm, K Pawłowski, K Rzążewski, M A Kristensen, J J Arlt
The investigation of atom number fluctuations in quantum gases at finite temperatures showcases the ongoing challenges in understanding complex quantum systems. Recently, the microcanonical nature of atom number fluctuations in weakly interacting Bose–Einstein condensates was observed. This motivates an investigation of the thermal component of partially condensed Bose gases, due to the conservation of the total atom number. Here, we present a combined analysis of both components, including a comprehensive analysis of the uncertainties in the preparation and parameter extraction of partially condensed quantum gases. This enables a complementary observation of the thermal atom number fluctuations and yields and improved value of the peak BEC atom number fluctuations ΔNp,02=(3.7±7)×105 close to the critical temperature. This corresponds to a reduction by 41% with respect to previous analysis and corroborates the microcanonical nature of the fluctuations. The analysis of noise contributions due to the preparation and evaluation of partially condensed Bose gases is based on Monte Carlo simulations of optical density profiles. Importantly, this allows for an estimation of the technical noise contributions to the atom number and temperature, which is generally applicable in the field of ultracold atoms.
{"title":"Atom number fluctuations in Bose gases—statistical analysis of parameter estimation","authors":"T Vibel, M B Christensen, R M F Andersen, L N Stokholm, K Pawłowski, K Rzążewski, M A Kristensen, J J Arlt","doi":"10.1088/1361-6455/ad7458","DOIUrl":"https://doi.org/10.1088/1361-6455/ad7458","url":null,"abstract":"The investigation of atom number fluctuations in quantum gases at finite temperatures showcases the ongoing challenges in understanding complex quantum systems. Recently, the microcanonical nature of atom number fluctuations in weakly interacting Bose–Einstein condensates was observed. This motivates an investigation of the thermal component of partially condensed Bose gases, due to the conservation of the total atom number. Here, we present a combined analysis of both components, including a comprehensive analysis of the uncertainties in the preparation and parameter extraction of partially condensed quantum gases. This enables a complementary observation of the thermal atom number fluctuations and yields and improved value of the peak BEC atom number fluctuations <inline-formula>\u0000<tex-math><?CDATA $Delta N_mathrm{p,0}^2 = (3.7pm7)times10^5$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:msubsup><mml:mi>N</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">p</mml:mi><mml:mo>,</mml:mo><mml:mn>0</mml:mn></mml:mrow><mml:mn>2</mml:mn></mml:msubsup><mml:mo>=</mml:mo><mml:mo stretchy=\"false\">(</mml:mo><mml:mn>3.7</mml:mn><mml:mo>±</mml:mo><mml:mn>7</mml:mn><mml:mo stretchy=\"false\">)</mml:mo><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>5</mml:mn></mml:msup></mml:mrow></mml:math><inline-graphic xlink:href=\"bad7458ieqn1.gif\"></inline-graphic></inline-formula> close to the critical temperature. This corresponds to a reduction by 41% with respect to previous analysis and corroborates the microcanonical nature of the fluctuations. The analysis of noise contributions due to the preparation and evaluation of partially condensed Bose gases is based on Monte Carlo simulations of optical density profiles. Importantly, this allows for an estimation of the technical noise contributions to the atom number and temperature, which is generally applicable in the field of ultracold atoms.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"68 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2024-08-30DOI: 10.1088/1361-6455/ad6b63
Vladyslav Unukovych, Andrii Sotnikov
We study an SU(4)-symmetric ultracold fermionic mixture in a cubic optical lattice with a variable tunneling amplitude along one particular crystallographic axis in the crossover region from the two- to three-dimensional spatial geometry. To theoretically analyze the emerging magnetic phases and physical observables, we describe the system within the framework of the Fermi–Hubbard model and apply dynamical mean-field theory. We show that in two limiting cases of anisotropy, there are two phases with different antiferromagnetic orderings in the zero temperature limit and we determine a region of their coexistence. We also study the stability regions of different magnetically ordered states and density profiles of the gas in the harmonic optical trap.
{"title":"Anisotropy-driven magnetic phase transitions in SU(4)-symmetric Fermi gas in three-dimensional optical lattices","authors":"Vladyslav Unukovych, Andrii Sotnikov","doi":"10.1088/1361-6455/ad6b63","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6b63","url":null,"abstract":"We study an SU(4)-symmetric ultracold fermionic mixture in a cubic optical lattice with a variable tunneling amplitude along one particular crystallographic axis in the crossover region from the two- to three-dimensional spatial geometry. To theoretically analyze the emerging magnetic phases and physical observables, we describe the system within the framework of the Fermi–Hubbard model and apply dynamical mean-field theory. We show that in two limiting cases of anisotropy, there are two phases with different antiferromagnetic orderings in the zero temperature limit and we determine a region of their coexistence. We also study the stability regions of different magnetically ordered states and density profiles of the gas in the harmonic optical trap.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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：