Dynamics of an Open System for Repeated Harmonic Perturbation

We use the Kossakowski-Lindblad-Davies formalism to consider an open system defined as the Markovian extension of one-mode quantum oscillator S, perturbed by a piecewise stationary harmonic interaction with a chain of oscillators C. The long-time asymptotic behaviour of various subsystems of S+C are obtained in the framework of the dual W-dynamical system approach

Near-Infrared Spectroscopy of Very Low-Luminosity Young Stellar Objects in the Taurus Molecular Cloud

We have carried out near-infrared spectroscopic observations of 23 very low-luminosity young stellar object (YSO) candidates and 5 their companions in Heiles Cloud 2, one of the densest parts of the Taurus molecular cloud. Twelve objects were confirmed as YSOs by Br gamma feature. The effective temperatures of the YSOs and of the companions are estimated from the 2.26 micron feature, the 2.21 micron feature, and the H2O band strengths. Detailed comparisons of our photometric and spectroscopic observations with evolutionary tracks on the HR diagram suggest some objects to be very low-mass YSOs.Comment: 15 pages, 19 figures. PASJ accepte

Phonon Transmission Rate, Fluctuations, and Localization in Random Semiconductor Superlattices: Green's Function Approach

We analytically study phonon transmission and localization in random superlattices by using a Green's function approach. We derive expressions for the average transmission rate and localization length, or Lyapunov exponent, in terms of the superlattice structure factor. This is done by considering the backscattering of phonons, due to the complex mass density fluctuations, which incorporates all of the forward scattering processes. These analytical results are applied to two types of random superlattices and compared with numerical simulations based on the transfer matrix method. Our analytical results show excellent agreement with the numerical data. A universal relation for the transmission fluctuations versus the average transmission is derived explicitly, and independently confirmed by numerical simulations. The transient of the distribution of transmission to the log-normal distribution for the localized phonons is also studied.Comment: 36 pages, Late

Singlet-triplet splitting, correlation and entanglement of two electrons in quantum dot molecules

Starting with an accurate pseudopotential description of the single-particle states, and following by configuration-interaction treatment of correlated electrons in vertically coupled, self-assembled InAs/GaAs quantum dot-molecules, we show how simpler, popularly-practiced approximations, depict the basic physical characteristics including the singlet-triplet splitting, degree of entanglement (DOE) and correlation. The mean-field-like single-configuration approaches such as Hartree-Fock and local spin density, lacking correlation, incorrectly identify the ground state symmetry and give inaccurate values for the singlet-triplet splitting and the DOE. The Hubbard model gives qualitatively correct results for the ground state symmetry and singlet-triplet splitting, but produces significant errors in the DOE because it ignores the fact that the strain is asymmetric even if the dots within a molecule are identical. Finally, the Heisenberg model gives qualitatively correct ground state symmetry and singlet-triplet splitting only for rather large inter-dot separations, but it greatly overestimates the DOE as a consequence of ignoring the electron double occupancy effect.Comment: 13 pages, 9 figures. To appear in Phys. Rev.

Deafness and Trauma: A Preliminary Investigation of Trauma within Deaf Domestic Violence Survivors

Deaf individuals in the United States face an increased risk of criminal victimization than their hearing counterparts. In particular, Deaf and Hard-of-Hearing are at a significantly higher risk of becoming victims of domestic violence. Unfortunately, the few scholarly studies that exist reveal that survivors within the Deaf population experience significant barriers when attempting to seek mental health treatment. Likewise, there is a significant lack of literature on extant psychometric tools available to measure trauma and PTSD within the Deaf community. This study analyzes the psychometric properties of the PTSD Checklist-5 (PCL-5) and the Impact of Event Scale-Revised (IES-R) in a sample of Deaf adult female survivors of domestic violence. Demographic and qualitative information, including barriers to help-seeking and relationship to the Deaf community, are also reported. Policy implications and future research implications are discussed

Quantum Phonon Optics: Coherent and Squeezed Atomic Displacements

In this paper we investigate coherent and squeezed quantum states of phonons. The latter allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of coherent states. The expectation values and quantum fluctuations of both the atomic displacement and the lattice amplitude operators are calculated in these states---in some cases analytically. We also study the possibility of squeezing quantum noise in the atomic displacement using a polariton-based approach.Comment: 6 pages, RevTe