No abstract

We study dynamics of bosonic atoms on a two dimensional square lattice, where atomic interactions are long ranged with either a box or soft-core shape. The latter can be realized through laser dressing ground state atoms to electronically excited Rydberg states. When the range of interactions is equal or larger than the lattice constant, the system is governed by an extended Bose-Hubbard model. We propose a quench process by varying the atomic hopping linearly across phase boundaries of the Mott insulator-supersolid and supersolid-superfluid phases. Starting from a Mott insulator state, dynamical evolution exhibits a universal behaviour at the early stage. We numerically find that the universality is largely independent of interactions during this stage. However, dynamical evolution could be significantly altered by long-range interactions at later times. We demonstrate that density wave excitations are important below a critical quench rate, where non-universal dynamics is found. We also show that the quench dynamics can be analysed through time-of-flight images, i.e. measuring the momentum distribution and noise correlations. arXiv:1907.02028v1 [cond-mat.quant-gas]

Recent advances in the preparation, control and measurement of atomic gases have led to new insights into the quantum world and unprecedented metrological sensitivities, e.g. in measuring gravitational forces and magnetic fields. The full potential of applying such capabilities to areas as diverse as biomedical imaging, non-invasive underground mapping, and GPS-free navigation can only be realised with the scalable production of efficient, robust and portable devices. We introduce additive manufacturing as a production technique of quantum device components with unrivalled design freedom and rapid prototyping. This provides a step change in efficiency, compactness and facilitates systems integration. As a demonstrator we present an ultrahigh vacuum compatible ultracold atom source dissipating less than ten milliwatts of electrical power during field generation to produce large samples of cold rubidium gases. This disruptive technology opens the door to drastically improved integrated structures, which will further reduce size and assembly complexity in scalable series manufacture of bespoke portable quantum devices.

Understanding how the human body senses small‐scale heating and cooling stimuli can help researchers evaluate thermal comfort effects and health risks of thermal stimulus combinations under complex thermal exposure. Two experiments measured high‐density thermal sensitivity on the hand to investigate whether the initial thermal states and stimulus intensities affect thermal sensitivity. After pilot tests, a 23°C cold‐water bath and a 41°C hot‐water bath were applied to create initial states deviating from thermal neutrality. The whole hand and part of the wrist with all test spots were immersed for 1 min and dried by a towel. Results showed that cold sensitivity and warmth sensitivity have a linear relationship with each other, but 16 of 20 subjects (80%) were more sensitive to cooling than to heating. The 1‐min water‐bath treatment significantly reduced hand thermal sensitivity. Compared with a thermally neutral state, a cold‐water bath and hot‐water bath reduced cold sensitivity by 22% and 61%, respectively, and reduced warmth sensitivity by 47% and 51%, respectively. Under a thermally neutral state, the perceptible thresholds for cooling and heating stimuli were −1.3°C and +1.8°C, respectively. Comfortable stimulating temperature ranges were 24°C–30°C for cooling and 34°C–39°C for heating. Thermal sensitivity differences among stimulus intensities were small, but differences among test spots and subjects were significant.

Functional polymer materials have shown great application potential in the field of information storage. Nevertheless, the majority of polymer-based memory devices are restricted to binary storage and exhibit limited capacity. In this study, naphthalene benzimidazole acceptor units were connected to fluorene/carbazole donor, and four new donor−acceptor bipolar-conjugated copolymers were achieved via the Suzuki cross-coupling reaction. Compared with pure fluorene/carbazole polymers, these polymers used in storage devices exhibit a special ternary-resistance switch memory mechanism, and their switching current ratios are high, which are 1