Pub Date : 2024-09-19DOI: 10.1103/physrevresearch.6.l032070
Pyae Hein Htet, Debasish Das, Eric Lauga
Flagellated bacteria are hydrodynamically attracted to rigid walls, yet past work shows a “hovering” state where they swim stably at a finite height above surfaces. We use numerics and theory to reveal the physical origin of hovering. Simulations first show that hovering requires an elongated cell body and results from a tilt away from the wall. Theoretical models then identify two essential asymmetries: the response of width-asymmetric cells to active flows created by length-asymmetric cells. A minimal model reconciles near- and far-field hydrodynamics, capturing all key features of hovering.
{"title":"Hydrodynamic hovering of swimming bacteria above surfaces","authors":"Pyae Hein Htet, Debasish Das, Eric Lauga","doi":"10.1103/physrevresearch.6.l032070","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032070","url":null,"abstract":"Flagellated bacteria are hydrodynamically attracted to rigid walls, yet past work shows a “hovering” state where they swim stably at a finite height above surfaces. We use numerics and theory to reveal the physical origin of hovering. Simulations first show that hovering requires an elongated cell body and results from a tilt away from the wall. Theoretical models then identify two essential asymmetries: the response of width-asymmetric cells to active flows created by length-asymmetric cells. A minimal model reconciles near- and far-field hydrodynamics, capturing all key features of hovering.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"194 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1103/physrevresearch.6.033318
Ming Li, Youjin Deng
The site percolation on the triangular lattice stands out as one of the few exactly solved statistical systems. By initially configuring critical percolation clusters of this model and randomly reassigning the color of each percolation cluster, we obtain coarse-grained configurations by merging adjacent clusters that share the same color. It is shown that the process can be infinitely iterated in the infinite-lattice limit, leading to an iterative site percolation model. We conjecture from the self-matching argument that percolation clusters remain fractal for any finite generation, which can even take any positive real number by a generalized process. Extensive simulations are performed, and, from the generation-dependent fractal dimension, a continuous family of previously unknown universalities is revealed.
{"title":"Iterative site percolation on triangular lattice","authors":"Ming Li, Youjin Deng","doi":"10.1103/physrevresearch.6.033318","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033318","url":null,"abstract":"The site percolation on the triangular lattice stands out as one of the few exactly solved statistical systems. By initially configuring critical percolation clusters of this model and randomly reassigning the color of each percolation cluster, we obtain coarse-grained configurations by merging adjacent clusters that share the same color. It is shown that the process can be infinitely iterated in the infinite-lattice limit, leading to an iterative site percolation model. We conjecture from the self-matching argument that percolation clusters remain fractal for any finite generation, which can even take any positive real number by a generalized process. Extensive simulations are performed, and, from the generation-dependent fractal dimension, a continuous family of previously unknown universalities is revealed.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1103/physrevresearch.6.033319
Ming Li, Junfeng Wang, Youjin Deng
Explosive percolation (EP) has received significant research attention due to its rich and anomalous phenomena near criticality. In our recent study [Phys. Rev. Lett.130, 147101 (2023)], we demonstrated that the correct critical behaviors of EP in infinite dimensions (complete graph) can be accurately extracted using the event-based method, with finite-size scaling behaviors still described by the standard finite-size scaling theory. We perform an extensive simulation of EPs on hypercubic lattices ranging from dimensions to 6, and find that the critical behaviors consistently obey the standard finite-size scaling theory. Consequently, we obtain a high-precision determination of the percolation thresholds and critical exponents, revealing that EPs governed by the product and sum rules belong to different universality classes. Remarkably, despite the mean of the dynamic pseudocritical point deviating from the infinite-lattice criticality by a distance determined by the -dependent correlation-length exponent, follows a normal (Gaussian) distribution across all dimensions, with a standard deviation proportional to , where denotes the system volume. A theoretical argument associated with the central-limit theorem is further proposed to understand the probability distribution of . These findings offer a comprehensive understanding of critical behaviors in EPs across various dimensions, revealing a different dimension-dependence compared to standard bond percolation.
爆炸性渗滤（EP）因其临界点附近丰富的反常现象而备受研究关注。在我们最近的研究[Phys. Rev. Lett. 130, 147101 (2023)]中，我们证明了使用基于事件的方法可以准确地提取无限维（完整图）EP 的正确临界行为，而有限尺寸缩放行为仍由标准的有限尺寸缩放理论描述。我们在维数从 d=2 到 6 的超立方晶格上对 EP 进行了大量模拟，发现临界行为始终遵循标准有限尺寸缩放理论。因此，我们获得了渗流阈值和临界指数的高精度测定，揭示了由积规则和和规则支配的 EP 属于不同的普遍性类别。值得注意的是，尽管动态伪临界点 TL 的平均值偏离无限晶格临界点的距离由依赖于 d 的相关长度指数决定，但 TL 在所有维度上都遵循正态（高斯）分布，标准偏差与 1/V 成正比，其中 V 表示系统体积。为理解 TL 的概率分布，进一步提出了与中心极限定理相关的理论论证。这些发现为我们全面理解 EP 在不同维度上的临界行为提供了依据，揭示了与标准键渗流不同的维度依赖性。
{"title":"Explosive percolation in finite dimensions","authors":"Ming Li, Junfeng Wang, Youjin Deng","doi":"10.1103/physrevresearch.6.033319","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033319","url":null,"abstract":"Explosive percolation (EP) has received significant research attention due to its rich and anomalous phenomena near criticality. In our recent study [<span>Phys. Rev. Lett.</span> <b>130</b>, 147101 (2023)], we demonstrated that the correct critical behaviors of EP in infinite dimensions (complete graph) can be accurately extracted using the event-based method, with finite-size scaling behaviors still described by the standard finite-size scaling theory. We perform an extensive simulation of EPs on hypercubic lattices ranging from dimensions <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>d</mi><mo>=</mo><mn>2</mn></mrow></math> to 6, and find that the critical behaviors consistently obey the standard finite-size scaling theory. Consequently, we obtain a high-precision determination of the percolation thresholds and critical exponents, revealing that EPs governed by the product and sum rules belong to different universality classes. Remarkably, despite the mean of the dynamic pseudocritical point <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"script\">T</mi><mi>L</mi></msub></math> deviating from the infinite-lattice criticality by a distance determined by the <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>d</mi></math>-dependent correlation-length exponent, <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"script\">T</mi><mi>L</mi></msub></math> follows a normal (Gaussian) distribution across all dimensions, with a standard deviation proportional to <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mn>1</mn><mo>/</mo><msqrt><mi>V</mi></msqrt></mrow></math>, where <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>V</mi></math> denotes the system volume. A theoretical argument associated with the central-limit theorem is further proposed to understand the probability distribution of <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi mathvariant=\"script\">T</mi><mi>L</mi></msub></math>. These findings offer a comprehensive understanding of critical behaviors in EPs across various dimensions, revealing a different dimension-dependence compared to standard bond percolation.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.033314
Bradraj Pandey, Satoshi Okamoto, Elbio Dagotto
Motivated by recent experimental reports of Majorana zero modes (MZMs) in quantum-dot systems at the “sweet spot,” where the electronic hopping is equal to the superconducting coupling , we study the time-dependent spectroscopy corresponding to the nontrivial fusion of MZMs. The term “nontrivial” refers to the fusion of Majoranas from different original pairs of MZMs, each with well-defined parities. We employ an experimentally accessible time-dependent real-space local density-of-states (LDOS) method to investigate the nontrivial MZM fusion outcomes in canonical chains and in a Y-shaped array of interacting electrons. In the case of quantum-dot chains where two pairs of MZMs are initially disconnected, after fusion we find equal-height peaks in the electron and hole components of the LDOS, signaling nontrivial fusion into both the vacuum and fermion channels with equal weight. For -junction quantum-dot chains, where the superconducting phase has opposite signs on the left and right portions of the chain, after the nontrivial fusion we observed the formation of an exotic two-site MZM near the center of the chain, coexisting with another single-site MZM. Furthermore, we also studied the fusion of three MZMs in the Y-shaped geometry. In this case, after the fusion we observed the novel formation of another exotic multisite MZM, with properties depending on the connection and geometry of the central region of the Y-shaped quantum-dot array.
最近有实验报告称量子点系统中的马约拉纳零模（Majorana zero modes，MZMs）处于 "甜蜜点"，即电子跳跃th等于超导耦合Δ，受此启发，我们研究了与MZMs非微不足道的融合相对应的随时间变化的光谱学。 术语 "非微不足道 "指的是来自不同原始MZMs对的马约拉纳的融合，每个MZMs对都有明确的奇偶性。我们采用一种可通过实验获得的、与时间相关的实空间局部态密度（LDOS）方法来研究经典链和相互作用电子的 Y 形阵列中的非难 MZM 融合结果。在量子点链中，两对 MZM 最初是断开的，在融合之后，我们发现 LDOS 的电子和空穴分量出现了等高的峰值，这表明非微观融合进入了真空 I 和费米子 Ψ 频道，且权重相等。对于π交界量子点链，超导相在链的左右两侧具有相反的符号，在非微不足道的融合之后，我们观察到在链中心附近形成了奇异的双位点 MZM，并与另一个单位点 MZM 共存。此外，我们还研究了 Y 形几何中三个 MZM 的融合。在这种情况下，我们观察到融合后形成了另一种奇特的多位 MZM，其特性取决于 Y 形量子点阵列中心区域的连接和几何形状。
{"title":"Nontrivial fusion of Majorana zero modes in interacting quantum-dot arrays","authors":"Bradraj Pandey, Satoshi Okamoto, Elbio Dagotto","doi":"10.1103/physrevresearch.6.033314","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033314","url":null,"abstract":"Motivated by recent experimental reports of Majorana zero modes (MZMs) in quantum-dot systems at the “sweet spot,” where the electronic hopping <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>t</mi><mi>h</mi></msub></math> is equal to the superconducting coupling <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">Δ</mi></math>, we study the time-dependent spectroscopy corresponding to the <i>nontrivial</i> fusion of MZMs. The term “nontrivial” refers to the fusion of Majoranas from different original pairs of MZMs, each with well-defined parities. We employ an experimentally accessible time-dependent real-space local density-of-states (LDOS) method to investigate the nontrivial MZM fusion outcomes in canonical chains and in a Y-shaped array of interacting electrons. In the case of quantum-dot chains where two pairs of MZMs are initially disconnected, after fusion we find equal-height peaks in the electron and hole components of the LDOS, signaling nontrivial fusion into both the vacuum <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>I</mi></math> and fermion <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi mathvariant=\"normal\">Ψ</mi></math> channels with equal weight. For <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>π</mi></math>-junction quantum-dot chains, where the superconducting phase has opposite signs on the left and right portions of the chain, after the nontrivial fusion we observed the formation of an exotic two-site MZM near the center of the chain, coexisting with another single-site MZM. Furthermore, we also studied the fusion of three MZMs in the Y-shaped geometry. In this case, after the fusion we observed the novel formation of another exotic multisite MZM, with properties depending on the connection and geometry of the central region of the Y-shaped quantum-dot array.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.l032068
Zecheng Shen, Jiarui Liu, Hao-Xin Wang, Yao Wang
Identifying the minimal model for cuprates is crucial for explaining the high- pairing mechanism. Recent photoemission experiments have suggested a significant near-neighbor attractive interaction in cuprate chains, favoring pairing instability. To determine its strength, we systematically investigate the dynamical spin structure factors using the density matrix renormalization group. Our analysis quantitatively reveals a notable softening in the two-spinon continuum, particularly evident in the intense spectrum at large momentum. This softening is primarily driven by the renormalization of the superexchange interaction, as determined by a comparison with the slave-boson theory. We also demonstrate the feasibility of detecting this spectral shift in thin-film samples using resonant inelastic x-ray scattering. Therefore, this provides a distinctive fingerprint for the attractive interaction, motivating future experiments to unveil essential ingredients in cuprates.
确定铜氧化物的最小模型对于解释高锝配对机制至关重要。最近的光辐射实验表明，在铜氧化物链中存在显著的近邻吸引力相互作用 V，这有利于配对的不稳定性。为了确定其强度，我们利用密度矩阵重正化群系统地研究了动态自旋结构因子 S(q,ω)。我们的定量分析揭示了双自旋子连续体的显著软化，尤其是在大动量下的强谱中更为明显。这种软化主要是由超交换相互作用的重正化驱动的，这是由与从玻色子理论的比较确定的。我们还证明了利用共振非弹性 X 射线散射在薄膜样品中探测这种光谱偏移的可行性。因此，这为有吸引力的相互作用提供了一个独特的指纹，促使未来的实验揭示铜氧化物的基本成分。
{"title":"Signatures of the attractive interaction in spin spectra of one-dimensional cuprate chains","authors":"Zecheng Shen, Jiarui Liu, Hao-Xin Wang, Yao Wang","doi":"10.1103/physrevresearch.6.l032068","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032068","url":null,"abstract":"Identifying the minimal model for cuprates is crucial for explaining the high-<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub><mi>T</mi><mi>c</mi></msub></math> pairing mechanism. Recent photoemission experiments have suggested a significant near-neighbor attractive interaction <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>V</mi></math> in cuprate chains, favoring pairing instability. To determine its strength, we systematically investigate the dynamical spin structure factors <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>S</mi><mo>(</mo><mi>q</mi><mo>,</mo><mi>ω</mi><mo>)</mo></mrow></math> using the density matrix renormalization group. Our analysis quantitatively reveals a notable softening in the two-spinon continuum, particularly evident in the intense spectrum at large momentum. This softening is primarily driven by the renormalization of the superexchange interaction, as determined by a comparison with the slave-boson theory. We also demonstrate the feasibility of detecting this spectral shift in thin-film samples using resonant inelastic x-ray scattering. Therefore, this provides a distinctive fingerprint for the attractive interaction, motivating future experiments to unveil essential ingredients in cuprates.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.033312
J. Griff-McMahon, S. Malko, V. Valenzuela-Villaseca, C. A. Walsh, G. Fiksel, M. J. Rosenberg, D. B. Schaeffer, W. Fox
Magnetic fields generated from a laser-foil interaction are measured with high fidelity using a proton radiography scheme with in situ x-ray fiducials. In contrast to prior findings under similar experimental conditions, this technique reveals the self-generated, Biermann-battery fields extend beyond the edge of the expanding plasma plume to a radius of over 3.5 mm by = ns. An analysis of two monoenergetic proton populations confirms that proton deflection is dominated by magnetic fields far from the interaction ( mm) and electric fields are insignificant. The results are not captured in state-of-the-art magnetohydrodynamics simulations and suggest the need to consider additional physics mechanisms for the magnetic field generation and transport in laser-solid interactions.
利用质子射线成像方案和原位 X 射线靶标，对激光-箔片相互作用产生的磁场进行了高保真测量。与之前在类似实验条件下的发现不同，该技术揭示了自产生的比尔曼电池磁场在 t=+1.4 ns 时超出了膨胀等离子体羽流的边缘，半径超过 3.5 mm。对两个单能质子群的分析证实，质子偏转主要由远离相互作用（2 毫米）的磁场主导，而电场则微不足道。最先进的磁流体力学模拟无法捕捉到这些结果，这表明需要考虑激光-固体相互作用中磁场产生和传输的其他物理机制。
{"title":"Measurements of extended magnetic fields in laser-solid interaction","authors":"J. Griff-McMahon, S. Malko, V. Valenzuela-Villaseca, C. A. Walsh, G. Fiksel, M. J. Rosenberg, D. B. Schaeffer, W. Fox","doi":"10.1103/physrevresearch.6.033312","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033312","url":null,"abstract":"Magnetic fields generated from a laser-foil interaction are measured with high fidelity using a proton radiography scheme with <i>in situ</i> x-ray fiducials. In contrast to prior findings under similar experimental conditions, this technique reveals the self-generated, Biermann-battery fields extend beyond the edge of the expanding plasma plume to a radius of over 3.5 mm by <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mi>t</mi></math>=<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mo>+</mo><mn>1.4</mn></math> ns. An analysis of two monoenergetic proton populations confirms that proton deflection is dominated by magnetic fields far from the interaction (<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mo>></mo><mn>2</mn></mrow></math> mm) and electric fields are insignificant. The results are not captured in state-of-the-art magnetohydrodynamics simulations and suggest the need to consider additional physics mechanisms for the magnetic field generation and transport in laser-solid interactions.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"194 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.033315
Simon K. Yung, Lorcán O. Conlon, Jie Zhao, Ping Koy Lam, Syed M. Assad
Measurement estimation bounds for local quantum multiparameter estimation, which provide lower bounds on possible measurement uncertainties, have so far been formulated in two ways: by extending the classical Cramér-Rao bound (e.g., the quantum Cramér-Rao bound and the Nagaoka Cramér-Rao bound) and by incorporating the parameter estimation framework with the uncertainty principle, as in the Lu-Wang uncertainty relation. In this work, we present a general framework that allows a direct comparison between these different types of estimation limits. Specifically, we compare the attainability of the Nagaoka Cramér-Rao bound and the Lu-Wang uncertainty relation, using analytical and numerical techniques. We show that these two limits can provide different information about the physically attainable precision. We present an example where both limits provide the same attainable precision and an example where the Lu-Wang uncertainty relation is not attainable even for pure states. We further demonstrate that the unattainability in the latter case arises because the figure of merit underpinning the Lu-Wang uncertainty relation (the difference between the quantum and classical Fisher information matrices) does not necessarily agree with the conventionally used figure of merit (mean-squared error). The results offer insights into the general attainability and applicability of the Lu-Wang uncertainty relation. Furthermore, our proposed framework for comparing bounds of different types may prove useful in other settings.
{"title":"Comparison of estimation limits for quantum two-parameter estimation","authors":"Simon K. Yung, Lorcán O. Conlon, Jie Zhao, Ping Koy Lam, Syed M. Assad","doi":"10.1103/physrevresearch.6.033315","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033315","url":null,"abstract":"Measurement estimation bounds for local quantum multiparameter estimation, which provide lower bounds on possible measurement uncertainties, have so far been formulated in two ways: by extending the classical Cramér-Rao bound (e.g., the quantum Cramér-Rao bound and the Nagaoka Cramér-Rao bound) and by incorporating the parameter estimation framework with the uncertainty principle, as in the Lu-Wang uncertainty relation. In this work, we present a general framework that allows a direct comparison between these different types of estimation limits. Specifically, we compare the attainability of the Nagaoka Cramér-Rao bound and the Lu-Wang uncertainty relation, using analytical and numerical techniques. We show that these two limits can provide different information about the physically attainable precision. We present an example where both limits provide the same attainable precision and an example where the Lu-Wang uncertainty relation is not attainable even for pure states. We further demonstrate that the unattainability in the latter case arises because the figure of merit underpinning the Lu-Wang uncertainty relation (the difference between the quantum and classical Fisher information matrices) does not necessarily agree with the conventionally used figure of merit (mean-squared error). The results offer insights into the general attainability and applicability of the Lu-Wang uncertainty relation. Furthermore, our proposed framework for comparing bounds of different types may prove useful in other settings.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.l032069
Zong-Kai Liu, Kong-Hao Sun, Albert Cabot, Federico Carollo, Jun Zhang, Zheng-Yuan Zhang, Li-Hua Zhang, Bang Liu, Tian-Yu Han, Qing Li, Yu Ma, Han-Chao Chen, Igor Lesanovsky, Dong-Sheng Ding, Bao-Sen Shi
Quantum many-body systems near phase transitions respond collectively to externally applied perturbations. We explore this phenomenon in a laser-driven dissipative Rydberg gas that is tuned to a bistable regime. Here two metastable phases coexist, which feature a low and high density of Rydberg atoms, respectively. The ensuing collective dynamics, which we monitor in situ, is characterized by stochastic collective jumps between these two macroscopically distinct many-body phases. We show that the statistics of these jumps can be controlled using a dual-tone microwave field. In particular, we find that the distribution of jump times develops peaks corresponding to subharmonics of the relative microwave detuning. Our study demonstrates the control of collective statistical properties of dissipative quantum many-body systems without the necessity of fine-tuning or of ultracold temperatures. Such robust many-body phenomena may find technological applications in sensing.
{"title":"Emergence of subharmonics in a microwave driven dissipative Rydberg gas","authors":"Zong-Kai Liu, Kong-Hao Sun, Albert Cabot, Federico Carollo, Jun Zhang, Zheng-Yuan Zhang, Li-Hua Zhang, Bang Liu, Tian-Yu Han, Qing Li, Yu Ma, Han-Chao Chen, Igor Lesanovsky, Dong-Sheng Ding, Bao-Sen Shi","doi":"10.1103/physrevresearch.6.l032069","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.l032069","url":null,"abstract":"Quantum many-body systems near phase transitions respond collectively to externally applied perturbations. We explore this phenomenon in a laser-driven dissipative Rydberg gas that is tuned to a bistable regime. Here two metastable phases coexist, which feature a low and high density of Rydberg atoms, respectively. The ensuing collective dynamics, which we monitor <i>in situ</i>, is characterized by stochastic collective jumps between these two macroscopically distinct many-body phases. We show that the statistics of these jumps can be controlled using a dual-tone microwave field. In particular, we find that the distribution of jump times develops peaks corresponding to subharmonics of the relative microwave detuning. Our study demonstrates the control of collective statistical properties of dissipative quantum many-body systems without the necessity of fine-tuning or of ultracold temperatures. Such robust many-body phenomena may find technological applications in sensing.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.033313
Dhruv Devulapalli, Eddie Schoute, Aniruddha Bapat, Andrew M. Childs, Alexey V. Gorshkov
We study the problem of implementing arbitrary permutations of qubits under interaction constraints in quantum systems that allow for arbitrarily fast local operations and classical communication (LOCC). In particular, we show examples of speedups over swap-based and more general unitary routing methods by distributing entanglement and using LOCC to perform quantum teleportation. We further describe an example of an interaction graph for which teleportation gives a logarithmic speedup in the worst-case routing time over swap-based routing. We also study limits on the speedup afforded by quantum teleportation—showing an upper bound on the separation in routing time for any interaction graph—and give tighter bounds for some common classes of graphs.
{"title":"Quantum routing with teleportation","authors":"Dhruv Devulapalli, Eddie Schoute, Aniruddha Bapat, Andrew M. Childs, Alexey V. Gorshkov","doi":"10.1103/physrevresearch.6.033313","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033313","url":null,"abstract":"We study the problem of implementing arbitrary permutations of qubits under interaction constraints in quantum systems that allow for arbitrarily fast local operations and classical communication (LOCC). In particular, we show examples of speedups over swap-based and more general unitary routing methods by distributing entanglement and using LOCC to perform quantum teleportation. We further describe an example of an interaction graph for which teleportation gives a logarithmic speedup in the worst-case routing time over swap-based routing. We also study limits on the speedup afforded by quantum teleportation—showing an <math xmlns=\"http://www.w3.org/1998/Math/MathML\"><mrow><mi>O</mi><mo>(</mo><msqrt><mrow><mi>N</mi><mo form=\"prefix\">log</mo><mi>N</mi></mrow></msqrt><mo>)</mo></mrow></math> upper bound on the separation in routing time for any interaction graph—and give tighter bounds for some common classes of graphs.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1103/physrevresearch.6.033311
Kritika Jain, Lewis Ruks, Fam le Kien, Thomas Busch
We study the interaction of emitters with a composite waveguide formed from two parallel optical nanofibers in regimes of experimental importance for atomic gases or solid-state emitters. Using the exact dyadic Green's function we comprehensively investigate the coupling efficiency and the fiber-induced Lamb shift accounting for variations in emitter positions and fiber configurations. This reveals coupling efficiencies and Purcell factors that are enhanced considerably beyond those using a single fiber waveguide, and robustness in the figures of merit. We finally investigate resonant dipole-dipole interactions and the generation of entanglement between two emitters mediated through the composite waveguide under excitation. We show that the concurrence can be enhanced for two fiber systems, such that entanglement may be present even in cases where it is zero for a single fiber. All-fiber systems are simple in construction and benefit from a wealth of existing telecommunications technologies, while enjoying strong couplings to emitters and offering interesting light-matter functionalities specific to slot waveguides.
{"title":"Strong dipole-dipole interactions via enhanced light-matter coupling in composite nanofiber waveguides","authors":"Kritika Jain, Lewis Ruks, Fam le Kien, Thomas Busch","doi":"10.1103/physrevresearch.6.033311","DOIUrl":"https://doi.org/10.1103/physrevresearch.6.033311","url":null,"abstract":"We study the interaction of emitters with a composite waveguide formed from two parallel optical nanofibers in regimes of experimental importance for atomic gases or solid-state emitters. Using the exact dyadic Green's function we comprehensively investigate the coupling efficiency and the fiber-induced Lamb shift accounting for variations in emitter positions and fiber configurations. This reveals coupling efficiencies and Purcell factors that are enhanced considerably beyond those using a single fiber waveguide, and robustness in the figures of merit. We finally investigate resonant dipole-dipole interactions and the generation of entanglement between two emitters mediated through the composite waveguide under excitation. We show that the concurrence can be enhanced for two fiber systems, such that entanglement may be present even in cases where it is zero for a single fiber. All-fiber systems are simple in construction and benefit from a wealth of existing telecommunications technologies, while enjoying strong couplings to emitters and offering interesting light-matter functionalities specific to slot waveguides.","PeriodicalId":20546,"journal":{"name":"Physical Review Research","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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