Found 696 results, showing the newest relevant preprints. Sort by relevancy only.Update me on new preprints

Improved stability for 2D attractive Bose gases

This implies, using previous results, that the

**many**-**body**ground states and dynamics converge to the NLS ones for an extended range of diluteness parameters. Expand abstract. We study the ground-state energy of N attractive bosons in the plane. The interaction is scaled for the gas to be dilute, so that the corresponding mean-field problem is a local non-linear Schr{\"o}dinger (NLS) equation. We improve the conditions under which one can prove that the

**many**-**body**problem is stable (of the second kind). This implies, using previous results, that the**many**-**body**ground states and dynamics converge to the NLS ones for an extended range of diluteness parameters.4 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Entanglement Hamiltonian of **Many**-**body** Dynamics in Strongly-correlated
Systems

These findings not only provide crucial information on how equilibrium statistical mechanics emerges in

**many**-**body**dynamics, but also add a tool to exploring quantum dynamics from perspective of entanglement Hamiltonian. Expand abstract. A powerful perspective in understanding non-equilibrium quantum dynamics is through the time evolution of its entanglement content. Yet apart from a few guiding principles for the entanglement entropy, to date, not much else is known about the refined characters of entanglement propagation. Here, we unveil signatures of the entanglement evolving and information propagation out-of-equilibrium, from the view of entanglement Hamiltonian. As a prototypical example, we study quantum quench dynamics of a one-dimensional Bose-Hubbard model by means of time-dependent density-matrix renormalization group simulation. Before reaching equilibration, it is found that a current operator emerges in entanglement Hamiltonian, implying that entanglement spreading is carried by particle flow. In the long-time limit subsystem enters a steady phase, evidenced by the dynamic convergence of the entanglement Hamiltonian to the expectation of a thermal ensemble. Importantly, entanglement temperature of steady state is spatially independent, which provides an intuitive trait of equilibrium. We demonstrate that these features are consistent with predictions from conformal field theory. These findings not only provide crucial information on how equilibrium statistical mechanics emerges in

**many**-**body**dynamics, but also add a tool to exploring quantum dynamics from perspective of entanglement Hamiltonian.4 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Optimal Selection of Structural Degree of Freedoms for Spceial Microscopic States to Characterize Disordered Structures

Despite this fact, our recent study reveals that a single (and a few additional) microscopic state (called projection state: PS), whose structure can be known a priori without r equiring thermodynamic information, can universally characterize equiibrium properties for disordered states, where their sturctures depends on configurational geometry before... Expand abstract.

For classical discrete systems under constant composition, statistical mechanics tells us that a set of microscopic state dominantly contributing to thermodynamically equilibrium state should depend on temperature as well as on

**many**-**body**interaction (i.e. thermodynamic information), through Boltzamann factor of exp(-bE). Despite this fact, our recent study reveals that a single (and a few additional) microscopic state (called projection state: PS), whose structure can be known a priori without r equiring thermodynamic information, can universally characterize equiibrium properties for disordered states, where their sturctures depends on configurational geometry before applying**many**-**body**interaction to the system. Although mathematical condition for the structures of PS have been rigorously established, practically effective condition for constructing the stuructures, especially for which set of a finite structural degree of freedoms (SDF) should be selected for considered coordination has not been clarified so far. We here tuckle this problem, proposing a quantitative and systematic criteria for an optimal set of SDFs. The present proposal enables to effectively constructing PSs for a limited system size, and also providing new insight into which set of SDFs should generally affects equilibrium properties along a chosen coordination, without using any thermodynamic information.4 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Many-**body** localization in the two dimensional Bose-Hubbard model

For any considered (local) interaction we find a mobility edge that terminates at sufficiently large disorder strength, implying the existence of a

**many**-**body**localized phase. Expand abstract. When dealing with

**many**-**body**localization, one of the hardest tasks is the investigation in more than one spatial dimension and for bosons. We investigate the disorder driven localization of the two dimensional Bose-Hubbard model by evaluating the full low energy quasi-particle spectrum via a recently developed fluctuation operator expansion. For any considered (local) interaction we find a mobility edge that terminates at sufficiently large disorder strength, implying the existence of a**many**-**body**localized phase. The finite size scaling is consistent with a Beresinskii-Kosterlitz-Thouless scenario. A direct comparison to a recent experiment yields an excellent match of the predicted transition point and scaling of single particle correlations.4 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Quantum noise in carbon nanotubes as a probe of correlations in the Kondo regime

Most of the time, electronic excitations in mesoscopic conductors are well described, around equilibrium, by non-interacting Landau quasi-particles. Expand abstract.

Most of the time, electronic excitations in mesoscopic conductors are well described, around equilibrium, by non-interacting Landau quasi-particles. This allows a good understanding of the transport properties in the linear regime. However, the role of interaction in the non-equilibrium properties beyond this regime has still to be established. A paradigmatic example is the Kondo

**many****body**state, which can be realized in a carbon nanotube (CNT) quantum dot for temperatures below the Kondo temperature $T_K$. As CNT possess spin and orbital quantum numbers, it is possible to investigate the twofold degenerate SU(2) Kondo effect as well as the four fold degenerate SU(4) state by tuning the degeneracies and filling factor. This article aims at providing a comprehensive review on our recent works on the Kondo correlations probed by quantum noise measurement both at low and high frequencies and demonstrate how current noise measurements yield new insight on interaction effects and dynamics of a Kondo correlated state.10 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Multifractality and its role in anomalous transport in the disordered XXZ spin-chain

Moreover it is not clear if similarly to the case of single-particle physics, multifractal properties of the

**many**-**body**eigenstates are related to anomalous transport, which is observed in this model. Expand abstract. The disordered XXZ model is a prototype model of the

**many**-**body**localization transition (MBL). Despite numerous studies of this model, the available numerical evidence of multifractality of its eigenstates is not very conclusive due severe finite size effects. Moreover it is not clear if similarly to the case of single-particle physics, multifractal properties of the**many**-**body**eigenstates are related to anomalous transport, which is observed in this model. In this work, using a state-of-the-art, massively parallel, numerically exact method, we study systems of up to 24 spins and show that a large fraction of the delocalized phase flows towards ergodicity in the thermodynamic limit, while a region immediately preceding the MBL transition appears to be multifractal in this limit. We discuss the implication of our finding on the mechanism of subdiffusive transport.10 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

The charge-dependent Bonn potentials with pseudovector pion-nucleon coupling

To apply the high-precision realistic nucleon-nucleon ($NN$) potentials on the investigations of relativistic many-body methods, the new versions of charge-dependent Bonn (CD-Bonn) $NN$ potential are constructed within the pseudovector pion-nucleon coupling instead of the pseudoscalar type in the original CD-Bonn potential worked out by Machleidt [Phys. Expand abstract.

To apply the high-precision realistic nucleon-nucleon ($NN$) potentials on the investigations of relativistic

**many**-**body**methods, the new versions of charge-dependent Bonn (CD-Bonn) $NN$ potential are constructed within the pseudovector pion-nucleon coupling instead of the pseudoscalar type in the original CD-Bonn potential worked out by Machleidt [Phys. Rev. C 63, 024001 (2001)]. Two effective scalar mesons are introduced, whose coupling constants with nucleon are independently determined at each partial wave for total angular momentum $J\leq 4$, to describe the charge dependence of $NN$ scattering data precisely, while the coupling constants between vector, pseudovector mesons and nucleon are identical in all channels. Three revised CD-Bonn potentials adopting the pseudovector pion-nucleon couplings (pvCD-Bonn) are generated by fitting the Nijmegen PWA phase shift data and deuteron binding energy with different pion-nucleon coupling strengths, which can reproduce the phase shifts at spin-single channels and low-energy $NN$ scattering parameters very well, and provide the significantly different mixing parameters at spin-triplet channels. Furthermore, the $D$-state probabilities of deuteron from these potentials range from $4.22\%$ to $6.05\%$. It demonstrates that these potentials contain different components of tensor force, which will be useful to discuss the roles of tensor force in nuclear few-**body**and**many**-**body**systems.11 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv

Experimental extraction of the quantum effective action for a
non-equilibrium **many**-**body** system

On the fundamental level, quantum fluctuations or entanglement lead to novel forms of complex dynamical behaviour in

**many**-**body**systems for which a description as emergent phenomena can be found within the framework of quantum field theory. Expand abstract. Far-from-equilibrium situations are ubiquitous in nature. They are responsible for a wealth of phenomena, which are not simple extensions of near-equilibrium properties, ranging from fluid flows turning turbulent to the highly organized forms of life. On the fundamental level, quantum fluctuations or entanglement lead to novel forms of complex dynamical behaviour in

**many**-**body**systems for which a description as emergent phenomena can be found within the framework of quantum field theory. A central quantity in these efforts, containing all information about the measurable physical properties, is the quantum effective action. Though the problem of non-equilibrium quantum dynamics can be exactly formulated in terms of the quantum effective action, the solution is in general beyond capabilities of classical computers. In this work, we present a strategy to determine the non-equilibrium quantum effective action using analog quantum simulators, and demonstrate our method experimentally with a quasi one-dimensional spinor Bose gas out of equilibrium. Building on spatially resolved snapshots of the spin degree of freedom, we infer the quantum effective action up to fourth order in an expansion in one-particle irreducible correlation functions at equal times. We uncover a strong suppression of the irreducible four-vertex emerging at low momenta, which solves the problem of dynamics in the highly occupied regime far from equilibrium where perturbative descriptions fail. Similar behaviour in this non-pertubative regime has been proposed in the context of early-universe cosmology. Our work constitutes a new realm of large-scale analog quantum computing, where the high level of control of synthetic quantum systems provides the means for the solution of long-standing theoretical problems in high-energy and condensed matter physics with an experimental approach.12 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Many-**body** echo

In this letter we propose a protocol to reverse a quantum many-body dynamical process. Expand abstract.

In this letter we propose a protocol to reverse a quantum

**many**-**body**dynamical process. We name it "many-**body**echo" because the underlying physics is closely related to the spin echo effect in nuclear magnetic resonance systems. We consider a periodical modulation of the interaction strength in a weakly interacting Bose condensate, which resonantly excites quasi-particles from the condensate. A dramatic phenomenon is that, after pausing the interaction modulation for half a period and then continuing on with the same modulation, nearly all the excited quasi-particles in the resonance modes will be absorbed back into the condensate. During the intermediate half period, the free evolution introduces a $\pi$ phase, which plays a role reminiscent of that played by the $\pi$-pulse in the spin echo. Comparing our protocol with another one implemented by the Chicago group in a recent experiment, we find that ours is more effective at reversing the**many**-**body**process. The difference between these two schemes manifests the physical effect of the micro-motion in the Floquet theory. Our scheme can be generalised to other periodically driven**many**-**body**systems.12 days ago

10/10 relevant

arXiv

10/10 relevant

arXiv

Semi-localization transition driven by a single asymmetrical tunneling

We investigate the

**many**-**body**ground state property of a one-dimensional tight-binding ring with an embedded single asymmetrical dimer based on exact solutions. Expand abstract. A local impurity usually only strongly affects few single-particle energy levels, thus cannot induce a quantum phase transition (QPT), or any macroscopic quantum phenomena in a

**many**-**body**system within the Hermitian regime. However, it may happen for a non-Hermitian impurity. We investigate the**many**-**body**ground state property of a one-dimensional tight-binding ring with an embedded single asymmetrical dimer based on exact solutions. We introduce the concept of semi-localization state to describe a new quantum phase, which is a crossover from extended to localized state. The peculiar feature is that the decay length is of the order of the system size, rather than fixed as a usual localized state. In addition, the spectral statistics is non-analytic as asymmetrical hopping strengths vary, resulting a sudden charge of the ground state. The distinguishing feature of such a QPT is that the density of ground state energy varies smoothly due to unbroken symmetry. However, there are other observables, such as the groundstate center of mass and average current, exhibit the behavior of second-order QPT. This behavior stems from time-reversal symmetry breaking of macroscopic number of single-particle eigen states.17 days ago

4/10 relevant

arXiv

4/10 relevant

arXiv