Pub Date : 2024-08-08DOI: 10.21468/scipostphys.17.2.039
Matteo Caldara, Andrea Richaud, Pietro Massignan, Alexander L. Fetter
Recent advances in cold-atom platforms have made real-time dynamics accessible, renewing interest in the motion of superfluid vortices in two-dimensional domains. Here we show that the energy and the trajectories of arbitrary vortex configurations may be computed on a complicated (curved or bounded) surface, provided that one knows a conformal map that links the latter to a simpler domain (like the full plane, or a circular boundary). We also prove that Hamilton's equations based on the vortex energy agree with the complex dynamical equations for the vortex dynamics, demonstrating that the vortex trajectories are constant-energy curves. We use these ideas to study the dynamics of vortices in a two-dimensional incompressible superfluid with an elliptical boundary, and we derive an analytical expression for the complex potential describing the hydrodynamic flow throughout the fluid. For a vortex inside an elliptical boundary, the orbits are nearly self-similar ellipses.
{"title":"Conformal maps and superfluid vortex dynamics on curved and bounded surfaces: The case of an elliptical boundary","authors":"Matteo Caldara, Andrea Richaud, Pietro Massignan, Alexander L. Fetter","doi":"10.21468/scipostphys.17.2.039","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.039","url":null,"abstract":"Recent advances in cold-atom platforms have made real-time dynamics accessible, renewing interest in the motion of superfluid vortices in two-dimensional domains. Here we show that the energy and the trajectories of arbitrary vortex configurations may be computed on a complicated (curved or bounded) surface, provided that one knows a conformal map that links the latter to a simpler domain (like the full plane, or a circular boundary). We also prove that Hamilton's equations based on the vortex energy agree with the complex dynamical equations for the vortex dynamics, demonstrating that the vortex trajectories are constant-energy curves. We use these ideas to study the dynamics of vortices in a two-dimensional incompressible superfluid with an elliptical boundary, and we derive an analytical expression for the complex potential describing the hydrodynamic flow throughout the fluid. For a vortex inside an elliptical boundary, the orbits are nearly self-similar ellipses.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"6 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.21468/scipostphys.17.2.038
Pierre Le Doussal, Naftali R. Smith, Nathan Argaman
We consider a system of $N$ spinless fermions, interacting with each other via a power-law interaction $epsilon/r^n$, and trapped in an external harmonic potential $V(r) = r^2/2$, in $d=1,2,3$ dimensions. For any $0 < n < d+2$, we obtain the ground-state energy $E_N$ of the system perturbatively in $epsilon$, $E_{N}=E_{N}^{≤ft(0)}+epsilon E_{N}^{≤ft(1)}+O≤ft(epsilon^{2})$. We calculate $E_{N}^{≤ft(1)}$ exactly, assuming that $N$ is such that the "outer shell" is filled. For the case of $n=1$ (corresponding to a Coulomb interaction for $d=3$), we extract the $N gg 1$ behavior of $E_{N}^{≤ft(1)}$, focusing on the corrections to the exchange term with respect to the leading-order term that is predicted from the local density approximation applied to the Thomas-Fermi approximate density distribution. The leading correction contains a logarithmic divergence, and is of particular importance in the context of density functional theory. We also study the effect of the interactions on the fermions' spatial density. Finally, we find that our result for $E_{N}^{≤ft(1)}$ significantly simplifies in the case where $n$ is even.
{"title":"Exact first-order effect of interactions on the ground-state energy of harmonically-confined fermions","authors":"Pierre Le Doussal, Naftali R. Smith, Nathan Argaman","doi":"10.21468/scipostphys.17.2.038","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.038","url":null,"abstract":"We consider a system of $N$ spinless fermions, interacting with each other via a power-law interaction $epsilon/r^n$, and trapped in an external harmonic potential $V(r) = r^2/2$, in $d=1,2,3$ dimensions. For any $0 < n < d+2$, we obtain the ground-state energy $E_N$ of the system perturbatively in $epsilon$, $E_{N}=E_{N}^{≤ft(0)}+epsilon E_{N}^{≤ft(1)}+O≤ft(epsilon^{2})$. We calculate $E_{N}^{≤ft(1)}$ exactly, assuming that $N$ is such that the \"outer shell\" is filled. For the case of $n=1$ (corresponding to a Coulomb interaction for $d=3$), we extract the $N gg 1$ behavior of $E_{N}^{≤ft(1)}$, focusing on the corrections to the exchange term with respect to the leading-order term that is predicted from the local density approximation applied to the Thomas-Fermi approximate density distribution. The leading correction contains a logarithmic divergence, and is of particular importance in the context of density functional theory. We also study the effect of the interactions on the fermions' spatial density. Finally, we find that our result for $E_{N}^{≤ft(1)}$ significantly simplifies in the case where $n$ is even.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.21468/scipostphys.17.2.036
Arnob Kumar Ghosh, Annica M. Black-Schaffer
Condensed matter systems are continuously subjected to dissipation, which often has adverse effects on quantum phenomena. We focus on the impact of dissipation on a superconducting Rashba nanowire. We reveal that the system can still host Majorana zero-modes (MZMs) with a finite lifetime in the presence of dissipation. Most interestingly, dissipation can also generate two kinds of dissipative boundary states: four robust zero-modes (RZMs) and two MZMs, in the regime where the non-dissipative system is topologically trivial. The MZMs appear via bulk gap closing and are topologically characterized by a winding number. The RZMs are not associated with any bulk states and possess no winding number, but their emergence is instead tied to exceptional points. Further, we confirm the stability of the dissipation-induced RZMs and MZMs in the presence of random disorder. Our study paves the way for both realizing and stabilizing MZMs in an experimental setup, driven by dissipation.
{"title":"Majorana zero-modes in a dissipative Rashba nanowire","authors":"Arnob Kumar Ghosh, Annica M. Black-Schaffer","doi":"10.21468/scipostphys.17.2.036","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.036","url":null,"abstract":"Condensed matter systems are continuously subjected to dissipation, which often has adverse effects on quantum phenomena. We focus on the impact of dissipation on a superconducting Rashba nanowire. We reveal that the system can still host Majorana zero-modes (MZMs) with a finite lifetime in the presence of dissipation. Most interestingly, dissipation can also generate two kinds of dissipative boundary states: four robust zero-modes (RZMs) and two MZMs, in the regime where the non-dissipative system is topologically trivial. The MZMs appear via bulk gap closing and are topologically characterized by a winding number. The RZMs are not associated with any bulk states and possess no winding number, but their emergence is instead tied to exceptional points. Further, we confirm the stability of the dissipation-induced RZMs and MZMs in the presence of random disorder. Our study paves the way for both realizing and stabilizing MZMs in an experimental setup, driven by dissipation.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"163 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.21468/scipostphyscore.7.3.051
Pierre Wulles, Sergey E. Skipetrov
lattice of two-level atoms coupled by the in-plane electromagnetic field may exhibit band gaps that can be opened either by applying an external magnetic field or by breaking the symmetry between the two triangular sublattices of which the honeycomb one is a superposition. We establish the conditions of band gap opening, compute the width of the gap, and characterize its topological property by a topological index (Chern number). The topological nature of the band gap leads to inversion of the population imbalance between the two triangular sublattices for modes with frequencies near band edges. It also prohibits a transition to the trivial limit of infinitely spaced, noninteracting atoms without closing the spectral gap. Surrounding the lattice by a Fabry-Pérot cavity with small intermirror spacing $d < pi/k_0$, where $k_0$ is the free-space wave number at the atomic resonance frequency, renders the system Hermitian by suppressing the leakage of energy out of the atomic plane without modifying its topological properties. In contrast, a larger $d$ allows for propagating optical modes that are built up due to reflections at the cavity mirrors and have frequencies inside the band gap of the free-standing lattice, thus closing the latter.
{"title":"Topological photonic band gaps in honeycomb atomic arrays","authors":"Pierre Wulles, Sergey E. Skipetrov","doi":"10.21468/scipostphyscore.7.3.051","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.051","url":null,"abstract":"lattice of two-level atoms coupled by the in-plane electromagnetic field may exhibit band gaps that can be opened either by applying an external magnetic field or by breaking the symmetry between the two triangular sublattices of which the honeycomb one is a superposition. We establish the conditions of band gap opening, compute the width of the gap, and characterize its topological property by a topological index (Chern number). The topological nature of the band gap leads to inversion of the population imbalance between the two triangular sublattices for modes with frequencies near band edges. It also prohibits a transition to the trivial limit of infinitely spaced, noninteracting atoms without closing the spectral gap. Surrounding the lattice by a Fabry-Pérot cavity with small intermirror spacing $d < pi/k_0$, where $k_0$ is the free-space wave number at the atomic resonance frequency, renders the system Hermitian by suppressing the leakage of energy out of the atomic plane without modifying its topological properties. In contrast, a larger $d$ allows for propagating optical modes that are built up due to reflections at the cavity mirrors and have frequencies inside the band gap of the free-standing lattice, thus closing the latter.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"35 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.21468/scipostphys.17.2.037
Jorge Luis Huamani Correa, Michal P. Nowak
We theoretically study the superconducting diode effect in a three-terminal Josephson junction. The diode effect in superconducting systems is typically related to the presence of a difference in the critical currents for currents flowing in the opposite direction. We show that in multi-terminal systems this effect occurs naturally without the need of the presence of any spin interactions and is a result of the presence of a relative shift between the Andreev bound states carrying the supercurrent. On an example of a three-terminal junction, we demonstrate that the non-reciprocal current in one of the superconducting contacts can be induced by proper phase biasing of the other contacts, provided that there are at least two Andreev bound states in the system and the symmetry of the system is broken. This result is confirmed in numerical models describing the junctions in both the short- and long-regime. By optimizing the geometry of the junction, we show that the efficiency of the realized superconducting diode exceeds 35%. We relate our predictions to recent experiments on multi-terminal junctions, in which non-reciprocal supercurrents were observed.
{"title":"Theory of universal diode effect in three-terminal Josephson junctions","authors":"Jorge Luis Huamani Correa, Michal P. Nowak","doi":"10.21468/scipostphys.17.2.037","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.037","url":null,"abstract":"We theoretically study the superconducting diode effect in a three-terminal Josephson junction. The diode effect in superconducting systems is typically related to the presence of a difference in the critical currents for currents flowing in the opposite direction. We show that in multi-terminal systems this effect occurs naturally without the need of the presence of any spin interactions and is a result of the presence of a relative shift between the Andreev bound states carrying the supercurrent. On an example of a three-terminal junction, we demonstrate that the non-reciprocal current in one of the superconducting contacts can be induced by proper phase biasing of the other contacts, provided that there are at least two Andreev bound states in the system and the symmetry of the system is broken. This result is confirmed in numerical models describing the junctions in both the short- and long-regime. By optimizing the geometry of the junction, we show that the efficiency of the realized superconducting diode exceeds 35%. We relate our predictions to recent experiments on multi-terminal junctions, in which non-reciprocal supercurrents were observed.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.21468/scipostphys.17.2.035
Elisabetta Armanini, Luca Griguolo, Luigi Guerrini
We compute the expectation values of BPS Wilson loops in the mass-deformed ABJM theory using the Fermi gas technique. We obtain explicit results in terms of Airy functions, effectively resumming the full 1/N expansion up to exponentially small terms. These expressions enable us to derive multi-point correlation functions for topological operators belonging to the stress tensor multiplet, in the presence of a 1/2-BPS Wilson line. From the one-point correlator, we recover the ABJM Bremsstrahlung function, confirming nicely previous results obtained through latitude Wilson loops. Likewise, higher point correlators can be used to extract iteratively new defect CFT data for higher dimensional topological operators. We present a detailed example of the dimension-two operator appearing in the OPE of two stress tensor multiplets.
{"title":"BPS Wilson loops in mass-deformed ABJM theory: Fermi gas expansions and new defect CFT data","authors":"Elisabetta Armanini, Luca Griguolo, Luigi Guerrini","doi":"10.21468/scipostphys.17.2.035","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.035","url":null,"abstract":"We compute the expectation values of BPS Wilson loops in the mass-deformed ABJM theory using the Fermi gas technique. We obtain explicit results in terms of Airy functions, effectively resumming the full 1/N expansion up to exponentially small terms. These expressions enable us to derive multi-point correlation functions for topological operators belonging to the stress tensor multiplet, in the presence of a 1/2-BPS Wilson line. From the one-point correlator, we recover the ABJM Bremsstrahlung function, confirming nicely previous results obtained through latitude Wilson loops. Likewise, higher point correlators can be used to extract iteratively new defect CFT data for higher dimensional topological operators. We present a detailed example of the dimension-two operator appearing in the OPE of two stress tensor multiplets.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"22 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.21468/scipostphys.17.2.034
Alexander Nikolaenko, Ya-Hui Zhang
Heavy fermion criticality has been a long-standing problem in condensed matter physics. Here we study a one-dimensional Kondo lattice model through numerical simulation and observe signatures of local criticality. We vary the Kondo coupling $J_K$ at fixed doping x. At large positive $J_K$, we confirm the expected conventional Luttinger liquid phase with $2k_F=frac{1+x}{2}$ (in units of $2pi$), an analogue of the heavy Fermi liquid (HFL) in the higher dimension. In the $J_K ≤ 0$ side, our simulation finds the existence of a fractional Luttinger liquid (LL$star$) phase with $2k_F=frac{x}{2}$, accompanied by a gapless spin mode originating from localized spin moments, which serves as an analogue of the fractional Fermi liquid (FL$star$) phase in higher dimensions. The LL$star$ phase becomes unstable and transitions to a spin-gapped Luther-Emery (LE) liquid phase at small positive $J_K$. Then we mainly focus on the "critical regime" between the LE phase and the LL phase. Approaching the critical point from the spin-gapped LE phase, we often find that the spin gap vanishes continuously, while the spin-spin correlation length in real space stays finite and small. For a certain range of doping, in a point (or narrow region) of $J_K$, the dynamical spin structure factor obtained through the time-evolving block decimation (TEBD) simulation shows dispersion-less spin fluctuations in a finite range of momentum space above a small energy scale (around $0.035 J$) that is limited by the TEBD accuracy. All of these results are unexpected for a regular gapless phase (or critical point) described by conformal field theory (CFT). Instead, they are more consistent with exotic ultra-local criticality with an infinite dynamical exponent $z=+$. The numerical discovery here may have important implications on our general theoretical understanding of the strange metals in heavy fermion systems. Lastly, we propose to simulate the model in a bilayer optical lattice with a potential difference.
重费米子临界是凝聚态物理学中一个长期存在的问题。在这里，我们通过数值模拟研究了一维近藤晶格模型，并观察到局部临界的特征。我们在固定掺杂x的条件下改变近藤耦合$J_K$。在大的正$J_K$条件下，我们证实了预期的传统鲁丁格液相，即2k_F=frac{1+x}{2}$（单位为$2pi$），这是高维重费米液体（HFL）的类似物。在 $J_K ≤ 0$ 边，我们的模拟发现存在一个分数卢丁格液体（LL$star$）相，其单位为$2k_F=frac{x}{2}$，伴随着一个源自局部自旋力矩的无间隙自旋模式，它是高维中分数费米液体（FL$star$）相的类似物。LL$star$相变得不稳定，并在小正$J_K$时过渡到自旋盖帽的卢瑟-埃默里（LE）液相。然后，我们主要关注 LE 相和 LL 相之间的 "临界机制"。从自旋掺杂的 LE 相接近临界点时，我们经常会发现自旋间隙连续消失，而实际空间中的自旋-自旋相关长度保持有限且很小。在一定的掺杂范围内，在$J_K$的一个点（或窄区域），通过时间渐变分块模拟（TEBD）得到的动态自旋结构因子显示，在有限的动量空间范围内，在小能量尺度（约 0.035 J$）以上无色散自旋波动，这受到 TEBD 精度的限制。所有这些结果都出乎共形场论（CFT）所描述的规则无隙相（或临界点）的意料。相反，它们更符合具有无限动态指数 $z=+$ 的奇异超局域临界。这里的数值发现可能对我们从理论上理解重费米子系统中的奇异金属具有重要意义。最后，我们提议在具有势差的双层光学晶格中模拟该模型。
{"title":"Numerical signatures of ultra-local criticality in a one dimensional Kondo lattice model","authors":"Alexander Nikolaenko, Ya-Hui Zhang","doi":"10.21468/scipostphys.17.2.034","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.034","url":null,"abstract":"Heavy fermion criticality has been a long-standing problem in condensed matter physics. Here we study a one-dimensional Kondo lattice model through numerical simulation and observe signatures of local criticality. We vary the Kondo coupling $J_K$ at fixed doping x. At large positive $J_K$, we confirm the expected conventional Luttinger liquid phase with $2k_F=frac{1+x}{2}$ (in units of $2pi$), an analogue of the heavy Fermi liquid (HFL) in the higher dimension. In the $J_K ≤ 0$ side, our simulation finds the existence of a fractional Luttinger liquid (LL$star$) phase with $2k_F=frac{x}{2}$, accompanied by a gapless spin mode originating from localized spin moments, which serves as an analogue of the fractional Fermi liquid (FL$star$) phase in higher dimensions. The LL$star$ phase becomes unstable and transitions to a spin-gapped Luther-Emery (LE) liquid phase at small positive $J_K$. Then we mainly focus on the \"critical regime\" between the LE phase and the LL phase. Approaching the critical point from the spin-gapped LE phase, we often find that the spin gap vanishes continuously, while the spin-spin correlation length in real space stays finite and small. For a certain range of doping, in a point (or narrow region) of $J_K$, the dynamical spin structure factor obtained through the time-evolving block decimation (TEBD) simulation shows dispersion-less spin fluctuations in a finite range of momentum space above a small energy scale (around $0.035 J$) that is limited by the TEBD accuracy. All of these results are unexpected for a regular gapless phase (or critical point) described by conformal field theory (CFT). Instead, they are more consistent with exotic ultra-local criticality with an infinite dynamical exponent $z=+$. The numerical discovery here may have important implications on our general theoretical understanding of the strange metals in heavy fermion systems. Lastly, we propose to simulate the model in a bilayer optical lattice with a potential difference.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"92 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.21468/scipostphyscore.7.3.050
Gianpaolo Torre, Jovan Odavić, Pierre Fromholz, Salvatore Marco Giampaolo, Fabio Franchini
Topological order comes in different forms, and its classification and detection is an important field of modern research. In this work, we show that the Disconnected Entanglement Entropy, a measure originally introduced to identify topological phases, is also able to unveil the long-range entanglement (LRE) carried by a single, fractionalized excitation. We show this by considering a quantum, delocalized domain wall excitation that can be introduced into a system by inducing geometric frustration in an antiferromagnetic spin chain. Furthermore, we show that the LRE of such systems is resilient against a quantum quench and the introduction of disorder, as it happens in traditional symmetry-protected topological phases. All these evidences establish the existence of a new phase induced by frustration with topological features despite not being of the usual type.
{"title":"Long-range entanglement and topological excitations","authors":"Gianpaolo Torre, Jovan Odavić, Pierre Fromholz, Salvatore Marco Giampaolo, Fabio Franchini","doi":"10.21468/scipostphyscore.7.3.050","DOIUrl":"https://doi.org/10.21468/scipostphyscore.7.3.050","url":null,"abstract":"Topological order comes in different forms, and its classification and detection is an important field of modern research. In this work, we show that the Disconnected Entanglement Entropy, a measure originally introduced to identify topological phases, is also able to unveil the long-range entanglement (LRE) carried by a single, fractionalized excitation. We show this by considering a quantum, delocalized domain wall excitation that can be introduced into a system by inducing geometric frustration in an antiferromagnetic spin chain. Furthermore, we show that the LRE of such systems is resilient against a quantum quench and the introduction of disorder, as it happens in traditional symmetry-protected topological phases. All these evidences establish the existence of a new phase induced by frustration with topological features despite not being of the usual type.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"51 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-05DOI: 10.21468/scipostphys.17.2.033
Soumyabrata Saha, Tridib Sadhu
We revisit the one-dimensional model of the symmetric simple exclusion process slowly coupled with two unequal reservoirs at the boundaries. In its non-equilibrium stationary state, the large deviations functions of density and current have been recently derived using exact microscopic analysis by Derrida, Hirschberg and Sadhu in [J. Stat. Phys. 182, 15 (2021)]. We present an independent derivation using the hydrodynamic approach of the macroscopic fluctuation theory (MFT). The slow coupling introduces additional boundary terms in the MFT-Action, which modifies the spatial boundary conditions for the associated variational problem. For the density large deviations, we explicitly solve the corresponding Euler-Lagrange equations using a simple local transformation of the optimal fields. For the current large deviations, our solution is obtained using the additivity principle. In addition to recovering the expression of the large deviations functions, our solution describes the most probable path for these rare fluctuations.
{"title":"Large deviations in the symmetric simple exclusion process with slow boundaries: A hydrodynamic perspective","authors":"Soumyabrata Saha, Tridib Sadhu","doi":"10.21468/scipostphys.17.2.033","DOIUrl":"https://doi.org/10.21468/scipostphys.17.2.033","url":null,"abstract":"We revisit the one-dimensional model of the symmetric simple exclusion process slowly coupled with two unequal reservoirs at the boundaries. In its non-equilibrium stationary state, the large deviations functions of density and current have been recently derived using exact microscopic analysis by Derrida, Hirschberg and Sadhu in [J. Stat. Phys. 182, 15 (2021)]. We present an independent derivation using the hydrodynamic approach of the macroscopic fluctuation theory (MFT). The slow coupling introduces additional boundary terms in the MFT-Action, which modifies the spatial boundary conditions for the associated variational problem. For the density large deviations, we explicitly solve the corresponding Euler-Lagrange equations using a simple local transformation of the optimal fields. For the current large deviations, our solution is obtained using the additivity principle. In addition to recovering the expression of the large deviations functions, our solution describes the most probable path for these rare fluctuations.","PeriodicalId":21682,"journal":{"name":"SciPost Physics","volume":"49 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141938843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-02DOI: 10.21468/scipostphys.17.2.032
Matthew Gorton, Anne Green
Primordial black holes (PBHs) can make up all of the dark matter (DM) if their mass, $m$, is in the so-called "asteroid-mass window", $10^{17} g ≲ m ≲ 10^{22} g$. Observational constraints on the abundance of PBHs are usually calculated assuming they all have the same mass, however this is unlikely to be a good approximation. PBHs formed from the collapse of large density perturbations during radiation domination are expected to have an extended mass function (MF), due to the effects of critical collapse. The PBH MF is often assumed to be lognormal, however it has recently been shown that other functions are a better fit to numerically calculated MFs. We recalculate both current and potential future constraints for these improved fitting functions. We find that for current constraints the asteroid-mass window narrows, but remains open (i.e. all of the DM can be in the form of PBHs) unless the PBH MF is wider than expected. Future evaporation and microlensing constraints may together exclude all of the DM being in PBHs, depending on the width of the PBH MF and also the shape of its low and high mass tails.
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