The Bose polaron problem: effect of mass imbalance on binding energy

By means of Quantum Monte Carlo methods we calculate the binding energy of an impurity immersed in a Bose-Einstein condensate at T = 0. The focus is on the attractive branch of the Bose polaron and on the role played by the mass imbalance between the impurity and the surrounding particles. For an impurity resonantly coupled to the bath, we investigate the dependence of the binding energy on the mass ratio and on the interaction strength within the medium. In particular, we determine the equation of state in the case of a static (infinite mass) impurity, where three-body correlations are irrelevant and the result is expected to be a universal function of the gas parameter. For the mass ratio corresponding to $^{40}$K impurities in a gas of $^{87}$Rb atoms we provide an explicit comparison with the experimental findings of a recent study carried out at JILA.Comment: 5 pages, 3 figure

Ionic polaron in a Bose-Einstein condensate

The ground state properties of a degenerate bosonic gas doped with an ion are investigated by means of quantum Monte Carlo simulations in three dimensions. The system features competing length and energy scales, which result in vastly different polaronic properties compared to neutral quantum impurities. Depending on whether a two-body bound state is supported or not by the atom-ion potential, we identify a transition between a polaron regime amenable to a perturbative treatment in the limit of weak atom-ion interactions and a many-body bound state with vanishing quasi-particle residue composed of hundreds of atoms. In order to analyze the structure of the corresponding states we examine the atom-ion and atom-atom correlation functions. Our findings are directly relevant to experiments using hybrid atom-ion setups that have recently attained the ultracold regime.Comment: 11 pages, 6 figures, 1 tabl

Ysovar: The First Sensitive, Wide-area, Mid-infrared Photometric Monitoring of the Orion Nebula Cluster

We present initial results from time-series imaging at infrared wavelengths of 0.9 deg^2 in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5 μm data over 40 consecutive days. We extracted light curves with ~3% photometric accuracy for ~2000 ONC members ranging from several solar masses down to well below the hydrogen-burning mass limit. For many of the stars, we also have time-series photometry obtained at optical (I_c) and/or near-infrared (JK_s ) wavelengths. Our data set can be mined to determine stellar rotation periods, identify new pre-main-sequence eclipsing binaries, search for new substellar Orion members, and help better determine the frequency of circumstellar disks as a function of stellar mass in the ONC. Our primary focus is the unique ability of 3.6 and 4.5 μm variability information to improve our understanding of inner disk processes and structure in the Class I and II young stellar objects (YSOs). In this paper, we provide a brief overview of the YSOVAR Orion data obtained in Fall 2009 and highlight our light curves for AA-Tau analogs—YSOs with narrow dips in flux, most probably due to disk density structures passing through our line of sight. Detailed follow-up observations are needed in order to better quantify the nature of the obscuring bodies and what this implies for the structure of the inner disks of YSOs

Pengaruh Teknik Kombinasi Hidroterapi Rendam Hangat dan Terapi Relaksasi Benson terhadap Penurunan Tekanan Darah pada Pasien Hipertensi di Puskesmas Maek Kecamatan Bukik Barisan

World Health Organization (WHO) in 2011, as much as 29% or 1.6 billion people worldwide suffer from hypertension. Hypertension prevalence in Indonesia has reached 25.8% of the total adult population. PHC Maek data obtained from medical records (MR) in the year 2014 the number of visits as many as 297 people. The purpose of this study was to determine the effect of combination technique hydrotherapy bath warm and benson relaxation therapy decrease blood pressurein patients hypertension in maek health center bukik barisan sub district lima puluh kota regency year 2015. This research has been conducted on June 22 until July 5, 2015 in Puskesmas Maek. This study uses Pre experiment with the design of one group pretest-posttest, then the data is processed by using the t test dependent. The results showed no significant effect of the combination of hydrotherapy techniques and warm soak benson relaxation therapy to decrease blood pressure in hypertensive patients in sub-district health centers Bukik maek row in 2015. Judging from the results of the analysis of paired samples T-test systolic blood pressure obtained with p value of 0.001 <0.05 and diastolic blood pressure with p value 0,001 <0,05. Recommendations result of this study is not only to treat hypertension using medical drugs but can also use warm soak hydrotherapy and relaxation therapy benson regularly as a companion treatment

Analyzing a Bose polaron across resonant interactions

Recently, two independent experiments reported the observation of long-lived polarons in a Bose-Einstein condensate, providing an excellent setting to study the generic scenario of a mobile impurity interacting with a quantum reservoir. Here, we expand the experimental analysis by disentangling the effects of trap inhomogeneities and the many-body continuum in one of these experiments. This makes it possible to extract the energy of the polaron at a well-defined density as a function of the interaction strength. Comparisons with quantum Monte-Carlo as well as diagrammatic calculations show good agreement, and provide a more detailed picture of the polaron properties at stronger interactions than previously possible. Moreover, we develop a semi-classical theory for the motional dynamics and three-body loss of the polarons, which partly explains a previously unresolved discrepancy between theory and experimental observations for repulsive interactions. Finally, we utilize quantum Monte-Carlo calculations to demonstrate that the findings reported in the two experiments are consistent with each other

Strong coupling Bose polarons in a two-dimensional gas

We study the properties of Bose polarons in two dimensions using quantum Monte Carlo techniques. Results for the binding energy, the effective mass, and the quasiparticle residue are reported for a typical strength of interactions in the gas and for a wide range of impurity-gas coupling strengths. A lower and an upper branch of the quasiparticle exist. The lower branch corresponds to an attractive polaron and spans from the regime of weak coupling where the impurity acts as a small density perturbation of the surrounding medium to deep bound states which involve many particles from the bath and extend as far as the healing length. The upper branch corresponds to an excited state where due to repulsion a low-density bubble forms around the impurity but might be unstable against decay into many-body bound states. Interaction effects strongly affect the quasiparticle properties of the polaron. In particular, in the strongly correlated regime, the impurity features a vanishing quasiparticle residue, signaling the transition from an almost free quasiparticle to a bound state involving many atoms from the bath.Comment: 8 pages, 5 figures