The 1S0^{1}\mathrm{S}_0-3P2^{3}\mathrm{P}_2 magnetic quadrupole transition in neutral strontium

We present a detailed investigation of the ultranarrow magnetic-quadrupole $^{1}\mathrm{S}_0$-$^{3}\mathrm{P}_2$ transition in neutral strontium and show how it can be made accessible for quantum simulation and quantum computation. By engineering the light shift in a one-dimensional optical lattice, we perform high-resolution spectroscopy and observe the characteristic absorption patterns for a magnetic quadrupole transition. We measure an absolute transition frequency of 446,647,242,704(5) kHz in $^{88}$Sr and an isotope shift for $^{87}$Sr of +62.93(6) MHz. In a proof-of-principle experiment, we use this transition to demonstrate local addressing in an optical lattice with 532 nm spacing with a Rayleigh-criterion resolution of 494(45) nm. Our results pave the way for applications of the magnetic quadrupole transition as an optical qubit and for single-site addressing in optical lattices.Comment: 19 pages, 9 figure

Cavity-Enhanced Optical Lattices for Scaling Neutral Atom Quantum Technologies to Higher Qubit Numbers

We demonstrate a cavity-based solution to scale up experiments with ultracold atoms in optical lattices by an order of magnitude over state-of-the-art free space lattices. Our two-dimensional optical lattices are created by power enhancement cavities with large mode waists of 489(8) $\mu$m and allow us to trap ultracold strontium atoms at a lattice depth of 60 $\mu$K by using only 80 mW of input light per cavity axis. We characterize these lattices using high-resolution clock spectroscopy and resolve carrier transitions between different vibrational levels. With these spectral features, we locally measure the lattice potential envelope and the sample temperature with a spatial resolution limited only by the optical resolution of the imaging system. The measured ground-band and trap lifetimes are 18(3) s and 59(2) s, respectively, and the lattice frequency (depth) is long-term stable on the MHz (0.1\%) level. Our results show that large, deep, and stable two-dimensional cavity-enhanced lattices can be created at any wavelength and can be used to scale up neutral-atom-based quantum simulators, quantum computers, sensors, and optical lattice clocks.Comment: 18 pages, 10 figure

A Geography of Cohabitation in the Americas, 1970-2010

In this chapter, we trace the geography of unmarried cohabitation in the Americas on an unprecedented geographical scale in family demography. We present the percentage of partnered women aged 25-29 in cohabitation across more than 19,000 local units of 39 countries, from Canada to Argentina, at two points in time, 2000 and 2010. The local geography is supplemented by a regional geography of cohabitation that covers five decades of data from 1960 to 2010. Our data derive primarily from the rich collection of census microdata amassed by the Centro Latinoamericano y Caribeño de Demografía (CELADE) of the United Nations and from the IPUMS-international collection of harmonized census microdata samples (Minnesota Population Center, Integrated public use microdata series, international: Version 6.3 [Machine-readable database]. University of Minnesota, Minneapolis, 2014). Our analyses unveil a substantial amount of spatial heterogeneity both within and across countries. Despite the spectacular rise in cohabitation, its regional patterning has remained relatively unchanged over the last decades, which points to the presence of geo-historical legacies in the present patterns of unmarried cohabitation

New opportunities for comparative male fertility research: insights from a new data resource based on high-quality birth registers

Obtaining cross-country comparative perspectives on male fertility has long been difficult, as male fertility is usually less well registered than female fertility. This paper presents analyses based on a new male fertility database providing data on more than 330 million live births. This new resource, made available in the Human Fertility Collection, allows for the first time a comparative perspective on male fertility in high-income countries using high-quality birth register data. Contrasting male and female fertility trends across 17 countries, we show that trends in disparities between male and female period fertility rates are driven to a large degree by the interplay of parental age and cohort size differences. For parental age differences at childbirth, we observe a tendency toward smaller disparities, except in Eastern Europe. This observation fits with expectations based on gender theories. However, variation across countries also seems to be driven by factors other than gender equality. &nbsp

Estimating men's fertility from vital registration data with missing values

Comparative perspectives on male fertility are still rare, in part because vital registration data often do not include paternal age information for a substantial number of births. We compare two imputation approaches that attempt to estimate male age-specific fertility rates and related measures for data in which the paternal age information is missing for a non-negligible number of cases. Taking births with paternal age information as a reference, the first approach uses the unconditional paternal age distribution, while the second approach considers the paternal age distribution conditional on the maternal age. To assess the performance of these two methods, we conduct simulations that mimic vital registration data for Sweden, the U.S., Spain, and Estonia. In these simulations, we vary the overall proportion and the age selectivity of missing values. We find that the conditional approach outperforms the unconditional approach in the majority of simulations, and should therefore generally be preferred.</p

Retraditionalization as a pathway to escape lowest-low fertility? Characteristics and prospects of the Eastern European “baby boom”

Over the last two decades, Belarus and Russia have witnessed substantial fertility increases that have catapulted their total fertility rates from lowest-low fertility to levels above 1.7 children per woman. While it is frequently argued that greater gender equality is an important mechanism for overcoming low fertility, these developments seem to have instead been accompanied by a retraditionalization of gender attitudes. This paper uses the 2017 Belarusian Generations and Gender Survey to investigate the characteristics and prospects of the Eastern European &ldquo;baby boom.&rdquo; We show that the fertility increases are driven by two main components: the recuperation of births postponed during the preceding post-communist transition crisis, and fertility increases among cohorts born in the 1980s. These cohorts also display very traditional gender attitudes. While the recuperation will not have a long-term impact, it is more uncertain whether or not the cohort fertility increases will be sustained