We have studied the effect of a non-Hermitian Bosonic bath on the dynamics of a two-level spin system. The non-Hermitian Hamiltonian of the bath is chosen such that it converges to the harmonic oscillator Hamiltonian when the non-Hermiticity is switched off. We calculate the dynamics of the spin system and found that the non-Hermiticity can have positive as well as negative effects on the coherence of the system. However, the decoherence can be completely eliminated by choosing the non-Hermiticity parameter and the phase of the system bath interaction appropriately. We have also studied the effect of this bath on the entanglement of a two-spin system when the bath is acting only on one spin.
Discrete-time quantum walks are known to exhibit exotic topological states and phases. Physical realization of quantum walks in a lossy environment may destroy these phases. We investigate the behaviour of topological states in quantum walks in the presence of a lossy environment. The environmental effects in the quantum walk dynamics are addressed using the non-Hermitian Hamiltonian approach. We show that the topological phases of the quantum walks are robust against moderate losses. The topological order in one-dimensional split-step quantum walk persists as long as the Hamiltonian respects exact $${{\mathcal {P}}}{{\mathcal {T}}}$$ P T -symmetry. Although the topological nature persists in two-dimensional quantum walks as well, the $${{\mathcal {P}}}{{\mathcal {T}}}$$ P T -symmetry has no role to play there. Furthermore, we observe topological phase transition in two-dimensional quantum walks that is induced by losses in the system.
Background: Physical symptoms of unknown aetiology are common in children and adolescents. Depression in this developmental age causes significant interpersonal and psychosocial problems including the risk for suicide. Objectives: Main objectives were to assess the somatic complaints and depressive symptoms of adolescent girls and to identify the relationship between these variables. Association between somatic complaints/depressive symptoms and selected socio personal variables was also analysed. Methods: A descriptive survey design was used in this study with a sample of 250 adolescent girls. The tools used for the data collection included a questionnaire to collect socio-personal data, an adapted version of Patient Health Questionnaire (PHQ-15) for assessing somatic complaints and Kutcher Adolescent Depression Scale (KADS) for assessing the depressive symptoms. The study was conducted among students of selected government schools of Kozhikode district of Kerala. Results: The results showed that about 1.6% had a high level of somatic complaints, 4% had medium and 40.4% had low somatic complaints. 15.2% of the participants were having depressive symptoms. The study found a significant positive correlation between somatic complaints and depressive symptoms. Conclusion: Screening for somatic complaints among adolescent girls help in the identification of depression in adolescent girls.
Optical nanofibersvery thin, tapered optical fibers where the waist diameter is less than the propagating light wavelengthhave been shown to be very useful tools for atom-light interactions. Their small size and relative ease of integration into optical fiber-based experimental setups, in addition to their minimal perturbation on magneto-optically trapped cold atoms, have ensured their adoption into cold atom physics. Here, we will discuss some recent applications of optical nanofibers to manipulate, trap, and control cold 87 Rb atoms in ground or Rydberg states. We will present some recent experimental and theoretical results related to the interactions between the atoms and the optical nanofiber field and introduce some of the limitations observed.
We perform the excitation of cold 87Rb atoms to Rydberg levels next to an optical nanofiber to exploit such an interface for use in quantum information processing.
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