Normal mode splitting and mechanical effects of an optical lattice in a ring cavity

A novel regime of atom-cavity physics is explored, arising when large atom samples dispersively interact with high-finesse optical cavities. A stable far detuned optical lattice of several million rubidium atoms is formed inside an optical ring resonator by coupling equal amounts of laser light to each propagation direction of a longitudinal cavity mode. An adjacent longitudinal mode, detunedby about 3 GHz, is used to perform probe transmission spectroscopy of the system. The atom-cavity coupling for the lattice beams and the probe is dispersive and dissipation results only from the finite photon-storage time. The observation of two well-resolved normal modes demonstrates the regime of strong cooperative coupling. The details of the normal mode spectrum reveal mechanical effects associated with the retroaction of the probe upon the optical lattice.Comment: 4 pages, 3 figure

Probing quantum phases of ultracold atoms in optical lattices by transmission spectra in cavity QED

Studies of ultracold atoms in optical lattices link various disciplines, providing a playground where fundamental quantum many-body concepts, formulated in condensed-matter physics, can be tested in much better controllable atomic systems, e.g., strongly correlated phases, quantum information processing. Standard methods to measure quantum properties of Bose-Einstein condensates (BECs) are based on matter-wave interference between atoms released from traps which destroys the system. Here we propose a nondestructive method based on optical measurements, and prove that atomic statistics can be mapped on transmission spectra of a high-Q cavity. This can be extremely useful for studying phase transitions between Mott insulator and superfluid states, since various phases show qualitatively distinct light scattering. Joining the paradigms of cavity quantum electrodynamics (QED) and ultracold gases will enable conceptually new investigations of both light and matter at ultimate quantum levels, which only recently became experimentally possible. Here we predict effects accessible in such novel setups.Comment: 6 pages, 3 figure

Dynamical Coupling between a Bose-Einstein Condensate and a Cavity Optical Lattice

A Bose-Einstein condensate is dispersively coupled to a single mode of an ultra-high finesse optical cavity. The system is governed by strong interactions between the atomic motion and the light field even at the level of single quanta. While coherently pumping the cavity mode the condensate is subject to the cavity optical lattice potential whose depth depends nonlinearly on the atomic density distribution. We observe bistability already below the single photon level and strong back-action dynamics which tunes the system periodically out of resonance.Comment: 5 pages, 4 figure

Orbital superfluidity in the PP-band of a bipartite optical square lattice

The successful emulation of the Hubbard model in optical lattices has stimulated world wide efforts to extend their scope to also capture more complex, incompletely understood scenarios of many-body physics. Unfortunately, for bosons, Feynmans fundamental "no-node" theorem under very general circumstances predicts a positive definite ground state wave function with limited relevance for many-body systems of interest. A promising way around Feynmans statement is to consider higher bands in optical lattices with more than one dimension, where the orbital degree of freedom with its intrinsic anisotropy due to multiple orbital orientations gives rise to a structural diversity, highly relevant, for example, in the area of strongly correlated electronic matter. In homogeneous two-dimensional optical lattices, lifetimes of excited bands on the order of a hundred milliseconds are possible but the tunneling dynamics appears not to support cross-dimensional coherence. Here we report the first observation of a superfluid in the $P$-band of a bipartite optical square lattice with $S$-orbits and $P$-orbits arranged in a chequerboard pattern. This permits us to establish full cross-dimensional coherence with a life-time of several ten milliseconds. Depending on a small adjustable anisotropy of the lattice, we can realize real-valued striped superfluid order parameters with different orientations $P_x \pm P_y$ or a complex-valued $P_x \pm i P_y$ order parameter, which breaks time reversal symmetry and resembles the $\pi$-flux model proposed in the context of high temperature superconductors. Our experiment opens up the realms of orbital superfluids to investigations with optical lattice models.Comment: 5 pages, 5 figure

Army Decade in Space

In the twelve short years since the announcement of the SMDC-ONE satellite initiative by Lieutenant General Kevin Campbell, then Commanding General of U.S. Army Space and Missile Defense Command (SMDC), SMDC has put in place an active program of satellite technology development and a Low Earth Orbit Investment Strategy that holds great promise for providing low-cost, responsive data from space as the next major evolution in technology to enable Multi-Domain Operations for the Army of 2028 and beyond. The first fruits of that initiative were seen ten years ago with launch and successful mission of the first SMDC-ONE satellite. This small satellite strategy has gained traction with Army and DoD leadership who embrace the small satellite paradigm. This paper discusses Army progress and lessons learned in the past ten years of small satellite efforts, discusses relationships with other organizations and looks forward to potential capabilities enabled by technology advancements and innovative partnerships

U.S. Army Small Space Update

In December 2010, the U.S. Army flew its first satellite in 50 years, the SMDC-ONE CubeSat. Placed in a very low orbit, the first SMDC-ONE mission lasted only 35 days but enjoyed great success in demonstrating the viability of CubeSats to perform exfiltration of unattended ground sensors data and serve as a communications relay between ground stations over 1000 land miles apart. The success of SMDC-ONE helped shape the U.S. Army’s Space and Missile Defense Command’s (SMDC) programmatic goals for finding new and innovative ways to implement space applications and technologies that aid the warfighter. Since 2010, SMDC has flown ten additional CubeSats including the three SMDC Nanosatellite Program-3 (SNaP) CubeSats currently on orbit (launched October 2015). This paper addresses several SMDC satellite-related development efforts including SNaP, Army Resilient Global On-the-move SATCOM (ARGOS) Ka-band communications microsatellites, Kestrel Eye (an imaging microsatellite), Kestrel Eye Ground Station (KEGS), Common Ground Station (CGS) for all future Army small satellites, supporting technologies including Small Business Innovative Research (SBIR) efforts, the Concepts Analysis Laboratory, SMDC Space Laboratory, the ACES RED effort and earlier responsive launch vehicle activities. Several of the lessons learned from previous as well as ongoing satellite activities are also covered

Quantum entanglement and disentanglement of multi-atom systems

We present a review of recent research on quantum entanglement, with special emphasis on entanglement between single atoms, processing of an encoded entanglement and its temporary evolution. Analysis based on the density matrix formalism are described. We give a simple description of the entangling procedure and explore the role of the environment in creation of entanglement and in disentanglement of atomic systems. A particular process we will focus on is spontaneous emission, usually recognized as an irreversible loss of information and entanglement encoded in the internal states of the system. We illustrate some certain circumstances where this irreversible process can in fact induce entanglement between separated systems. We also show how spontaneous emission reveals a competition between the Bell states of a two qubit system that leads to the recently discovered "sudden" features in the temporal evolution of entanglement. An another problem illustrated in details is a deterministic preparation of atoms and atomic ensembles in long-lived stationary squeezed states and entangled cluster states. We then determine how to trigger the evolution of the stable entanglement and also address the issue of a steered evolution of entanglement between desired pairs of qubits that can be achieved simply by varying the parameters of a given system.Comment: Review articl

Deletion of the Pichia pastoris KU70 Homologue Facilitates Platform Strain Generation for Gene Expression and Synthetic Biology

Targeted gene replacement to generate knock-outs and knock-ins is a commonly used method to study the function of unknown genes. In the methylotrophic yeast Pichia pastoris, the importance of specific gene targeting has increased since the genome sequencing projects of the most commonly used strains have been accomplished, but rapid progress in the field has been impeded by inefficient mechanisms for accurate integration. To improve gene targeting efficiency in P. pastoris, we identified and deleted the P. pastoris KU70 homologue. We observed a substantial increase in the targeting efficiency using the two commonly known and used integration loci HIS4 and ADE1, reaching over 90% targeting efficiencies with only 250-bp flanking homologous DNA. Although the ku70 deletion strain was noted to be more sensitive to UV rays than the corresponding wild-type strain, no lethality, severe growth retardation or loss of gene copy numbers could be detected during repetitive rounds of cultivation and induction of heterologous protein production. Furthermore, we demonstrated the use of the ku70 deletion strain for fast and simple screening of genes in the search of new auxotrophic markers by targeting dihydroxyacetone synthase and glycerol kinase genes. Precise knock-out strains for the well-known P. pastoris AOX1, ARG4 and HIS4 genes and a whole series of expression vectors were generated based on the wild-type platform strain, providing a broad spectrum of precise tools for both intracellular and secreted production of heterologous proteins utilizing various selection markers and integration strategies for targeted or random integration of single and multiple genes. The simplicity of targeted integration in the ku70 deletion strain will further support protein production strain generation and synthetic biology using P. pastoris strains as platform hosts

Identification of a mitotic recombination hotspot on chromosome III of the asexual fungus Aspergillus niger and its possible correlation elevated basal transcription

Genetic recombination is an important tool in strain breeding in many organisms. We studied the possibilities of mitotic recombination in strain breeding of the asexual fungus Aspergillus niger. By identifying genes that complemented mapped auxotrophic mutations, the physical map was compared to the genetic map of chromosome III using the genome sequence. In a program to construct a chromosome III-specific marker strain by selecting mitotic crossing-over in diploids, a mitotic recombination hotspot was identified. Analysis of the mitotic recombination hotspot revealed some physical features, elevated basal transcription and a possible correlation with purine stretches

Biological Earth observation with animal sensors.

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change