High accuracy measure of atomic polarizability in an optical lattice clock

Despite being a canonical example of quantum mechanical perturbation theory, as well as one of the earliest observed spectroscopic shifts, the Stark effect contributes the largest source of uncertainty in a modern optical atomic clock through blackbody radiation. By employing an ultracold, trapped atomic ensemble and high stability optical clock, we characterize the quadratic Stark effect with unprecedented precision. We report the ytterbium optical clock's sensitivity to electric fields (such as blackbody radiation) as the differential static polarizability of the ground and excited clock levels: 36.2612(7) kHz (kV/cm)^{-2}. The clock's fractional uncertainty due to room temperature blackbody radiation is reduced an order of magnitude to 3 \times 10^{-17}.Comment: 5 pages, 3 figures, 2 table

Cooperative research and development agreements at METC

The Morgantown Energy Technology Center (METC) is always interested in discussing partnering opportunities with those in the private sector. One way METC can work with the private sector and academia is through Cooperative Research and Development Agreements (CRADAs). From METC`s perspective, a good CRADA consists of two elements: a good project and a good CRADA partner. Good CRADA projects address goals that are beneficial to both the private sector participant and METC. Of primary interest to METC is the development and deployment of clean, efficient power generation technologies and environmental remediation technologies. For power generation, METC`s primary focus is on Integrated Gasification Combined Cycle (IGCC)systems, Pressurized Fluidized-Bed Combustion (PFBC) systems, Advanced Turbine Systems (ATS), Externally Fired Combined-Cycle (EFCC) power systems, fuel cell systems, and fuels technology systems. METC`s environmental remediation interests focus on the development of high-payoff technologies to clean up the inventory of DOE nuclear component manufacturing sites, and to manage DOE-generated waste faster, safer, and cheaper than environmental cleanup technologies that are currently available. Regarding CRADA partners, preference is given to small businesses and to business units located in the United States which agree that products resulting from the CRADA will be manufactured substantially in the United States

An atomic clock with 10−1810^{-18} instability

Atomic clocks have been transformational in science and technology, leading to innovations such as global positioning, advanced communications, and tests of fundamental constant variation. Next-generation optical atomic clocks can extend the capability of these timekeepers, where researchers have long aspired toward measurement precision at 1 part in $\bm{10^{18}}$. This milestone will enable a second revolution of new timing applications such as relativistic geodesy, enhanced Earth- and space-based navigation and telescopy, and new tests on physics beyond the Standard Model. Here, we describe the development and operation of two optical lattice clocks, both utilizing spin-polarized, ultracold atomic ytterbium. A measurement comparing these systems demonstrates an unprecedented atomic clock instability of $\bm{1.6\times 10^{-18}}$ after only $\bm{7}$ hours of averaging

Coherent optical phase transfer over a 32-km fiber with 1-s instability at 10−1710^{-17}

The phase coherence of an ultrastable optical frequency reference is fully maintained over actively stabilized fiber networks of lengths exceeding 30 km. For a 7-km link installed in an urban environment, the transfer instability is $6 \times 10^{-18}$ at 1-s. The excess phase noise of 0.15 rad, integrated from 8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link achieves similar performance. Using frequency combs at each end of the coherent-transfer fiber link, a heterodyne beat between two independent ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure

Relativistic coupled-cluster single-double calculations of positron-atom bound states

Relativistic coupled-cluster single-double approximation is used to calculate positron-atom bound states. The method is tested on closed-shell atoms such as Be, Mg, Ca, Zn, Cd, and Hg where a number of accurate calculations is available. It is then used to calculate positron binding energies for a range of open-shell transition metal atoms from Sc to Cu, from Y to Pd, and from Lu to Pt. These systems possess Feshbach resonances, which can be used to search for positron-atom binding experimentally through resonant annihilation or scattering.Comment: submitted to Phys. Rev.

Sub-femtosecond absolute timing precision with a 10 GHz hybrid photonic-microwave oscillator

We present an optical-electronic approach to generating microwave signals with high spectral purity. By circumventing shot noise and operating near fundamental thermal limits, we demonstrate 10 GHz signals with an absolute timing jitter for a single hybrid oscillator of 420 attoseconds (1Hz - 5 GHz)