Many-Body Quantum Dynamics of a Bosonic Josephson Junction with a Finite-Range Interaction

The out-of-equilibrium quantum dynamics of a Bose gas trapped in an asymmetric double well and interacting with a finite-range interaction has been studied in real space by solving the time-dependent many-body Schr\"odinger equation numerically accurately using the multiconfigurational time-dependent Hartree method for bosons (MCTDHB). We have focused on the weakly interacting limit where the system is essentially condensed. We have examined the impact of the range of the interaction on the dynamics of the system, both at the mean-field and many-body levels. Explicitly, we have studied the maximal and the minimal values of the many-body position variance in each cycle of oscillation, and the overall pace of its growth. We find that the range of the interaction affects the dynamics of the system differently for the right well and the left well. We have also examined the infinite-particle limit and find that even there, the impact of the range of the interaction can only be described by a many-body theory such as MCTDHB

Impact of the range of the interaction on the quantum dynamics of a bosonic Josephson junction

The out-of-equilibrium quantum dynamics of a bosonic Josephson junction (BJJ) with long-range interaction is studied in real space by solving the time-dependent many-body Schr\"odinger equation numerically accurately using the multiconfigurational time-dependent Hartree method for bosons. Having the many-boson wave-function at hand we can examine the impact of the range of the interaction on the properties of the BJJ dynamics, viz. density oscillations and their collapse, self trapping, depletion and fragmentation, as well as the position variance, both at the mean-field and many-body level. Explicitly, the frequency of the density oscillations and the time required for their collapse, the value of fragmentation at the plateau, the maximal and the minimal values of the position variance in each cycle of oscillation and the overall pace of its growth are key to our study. We find competitive effect between the interaction and the confining trap. The presence of the tail part of the interaction basically enhances the effective repulsion as the range of the interaction is increased starting from a short, finite range. But as the range becomes comparable with the trap size, the system approaches a situation where all the atoms feel a constant potential and the impact of the tail on the dynamics diminishes. There is an optimal range of the interaction in which physical quantities of the junction are attaining their extreme values.Comment: Contribution to the Special Issue of Chemical Physics dedicated to Professor Hans-Dieter Meyer on the occasion of his 70th birthday; few typos correcte

Macroscopic quantum many-body tunneling of attractive Bose-Einstein condensate in anharmonic trap

We study the stability of attractive atomic Bose-Einstein condensate and the macroscopic quantum many-body tunneling (MQT) in the anharmonic trap. We utilize correlated two-body basis function which keeps all possible two-body correlations. The anharmonic parameter ($\lambda$) is slowly tuned from harmonic to anharmonic. For each choice of $\lambda$ the many-body equation is solved adiabatically. The use of the van der Waals interaction gives realistic picture which substantially differs from the mean-field results. For weak anharmonicity, we observe that the attractive condensate gains stability with larger number of bosons compared to that in the pure harmonic trap. The transition from resonances to bound states with weak anharmonicity also differs significantly from the earlier study of Moiseyev {\it et.al.}[J. Phys. B: At. Mol. Opt. Phys. {\bf{37}}, L193 (2004)]. We also study the tunneling of the metastable condensate very close to the critical number $N_{cr}$ of collapse and observe that near collapse the MQT is the dominant decay mechanism compared to the two-body and three-body loss rate. We also observe the power law behavior in MQT near the critical point. The results for pure harmonic trap are in agreement with mean-field results. However we fail to retrieve the power law behavior in anharmonic trap although MQT is still the dominant decay mechanism.Comment: Accepted in Eur. Phys. J. D (2013

Lichen Planus-like Eruption Resulting from a Jellyfish Sting

Introduction: Contact with a jellyfish can cause a wide variety of conditions, ranging from cutaneous eruption to fatal cardiovascular and respiratory collapse. Cutaneous features can be both acute and chronic. We report a case of persistent lichen planus-like eruption in a young boy after a jellyfish sting, a hitherto unreported occurrence. Case presentation: A 15-year-old boy presented with multiple lichen planus-like violaceous papules over the lower part of his left thigh on the anterior aspect and also over the patellar region. He had a history of a jellyfish sting over his lower limbs incurred while bathing in the sea 4 weeks prior to presentation. Histopathology revealed a predominantly perivascular mononuclear cell infiltrate immediately beneath the dermoepidermal junction underneath the hyperplastic epidermis. The lesions significantly subsided with topical corticosteroid application. Conclusion: This case report demonstrates a new variant of chronic cutaneous change following a jellyfish sting. We report it because of its uniqueness and we believe that physicians should be aware of the possibility of an aquatic animal-induced disease when dealing with lesions with lichen planus-like morphology.&nbsp

Lichen planus-like eruption resulting from a jellyfish sting: a case report

<p>Abstract</p> <p>Introduction</p> <p>Contact with a jellyfish can cause a wide variety of conditions, ranging from cutaneous eruption to fatal cardiovascular and respiratory collapse. Cutaneous features can be both acute and chronic. We report a case of persistent lichen planus-like eruption in a young boy after a jellyfish sting, a hitherto unreported occurrence.</p> <p>Case presentation</p> <p>A 15-year-old boy presented with multiple lichen planus-like violaceous papules over the lower part of his left thigh on the anterior aspect and also over the patellar region. He had a history of a jellyfish sting over his lower limbs incurred while bathing in the sea four weeks prior to presentation. Histopathology revealed a predominantly perivascular mononuclear cell infiltrate immediately beneath the dermoepidermal junction underneath the hyperplastic epidermis. The lesions significantly subsided with topical corticosteroid application.</p> <p>Conclusion</p> <p>This case report demonstrates a new variant of chronic cutaneous change following a jellyfish sting. We report it because of its uniqueness and we believe that physicians should be aware of the possibility of an aquatic animal-induced disease when dealing with lesions with lichen planus-like morphology.</p

Many-body effects in the out-of-equilibrium dynamics of a composite bosonic Josephson junction

The out-of-equilibrium many-body quantum dynamics of an interacting Bose gas trapped in a one-dimensional composite double-well potential is studied by solving the many-body Schr\"odinger equation numerically accurately by employing the multiconfigurational time-dependent Hartree for bosons (MCTDHB) method. The composite double-well is formed by merging two deformed harmonic wells having a hump at their centre. We characterised the dynamics by the time evolution of survival probability, fragmentation, and many-particle position and momentum variances. Our study demonstrates the prominent role played by the higher orbitals in the dynamics and thereby highlighted the necessity of a many-body technique like MCTDHB which can take into account all the relevant orbitals for the accurate description of complex many-body dynamics. Further, we showed that the universality of fragmentation with respect to the number of particles corresponding to a particular interaction strength is also exhibited by the higher-order orbitals. Therefore, it is a robust phenomenon not limited to systems that can be described by two orbitals only