C. Fertig

Laser-cooled Rb clocks

We demonstrate a prototype of a laser-cooled /sup 87/Rb fountain clock and measure the frequency shift due to cold collisions. The shift is fractionally 30 times smaller than that in a laser-cooled Cs clock. We observe a density dependent pulling by the microwave cavity and use it to cancel the collision shift. We have also demonstrated a juggling atomic fountain to study cold collisions and we discuss the importance of juggling for future fountain clocks.

Laser-cooled /sup 87/Rb clock

Disclosed is an intercrosslinked multilayer polymeric article having at least one thermoplastic polymer layer intercrosslinked by UV radiation at the interface with a core layer of a crosslinkable polymer. The selection of the thermoplastic polymer and the crosslinkable polymer is such that a coextruded composite product of these materials has poor interlayer adhesion prior to radiation treatment. However, the interfacial intercrosslinking provides superior bonding between the layers. The same UV radiation for intercrosslinking typically can also cure the crosslinkable polymer to give the multilayer article excellent structural integrity. Also disclosed is a method for preparing an intercrosslinked multilayer polymeric article.

Laser-cooled Rb fountain clocks

We demonstrate a prototype of a laser-cooled /sup 87/Rb fountain clock and report a preliminary measurement of the frequency shift due to cold collisions. We find the shift to be much smaller than that in a laser-cooled Cs clock. We have recently demonstrated a juggling atomic fountain to study cold collisions. We discuss the importance of juggling for future fountain clocks and the problems and potential solutions.

RACE: laser-cooled Rb microgravity clock

RACE is a high performance Rb clock slated to fly on the International Space Station. RACE aims to realize high accuracy and short-term stability. The cold collision shift and multiple launching (juggling) have important implications for the design and the resulting clock accuracy and stability. We present and discuss the double clock design for RACE. This design reduces the noise contributions of the local oscillator and simplifies and enhances an accuracy evaluation of the clock.

Laser-cooled microgravity clocks

The principle advantage of microgravity for atomic clocks is interrogation times longer than 1 s. With a 10 s interrogation time, a clock has a 50 mHz linewidth suggesting that accuracies may potentially exceed 10/sup -16/. However, to achieve greater accuracy within the same averaging time, greater stability is needed. Achieving greater stability in a microgravity clock constrains the design differently than for earth based fountains. In this paper, we discuss the design considerations for laser-cooled microgravity clocks highlighting the considerations that differ from those for earth-based fountains. As in earthbased fountains, the frequency shift due to cold collisions plays an important role in the design of the clock. Given our predictions (and measurements) for the shift in laser-cooled Rb clocks, we currently anticipate building a high performance Rb clock and discuss the relative merits of Rb and Cs microgravity clocks. Finally, we present our tentative designs for two microgravity clocks.

A juggling Rb fountain clock and a direct measurement of population differences

We demonstrate a new atomic state detection scheme that directly measures the population difference of the two clock states using FM absorption spectroscopy. We also demonstrate a juggling Rb fountain clock that we will use to study collisions of juggled balls of atoms. Juggling can significantly improve the clocks short-term stability without requiring greater signal-to-noise or a larger cold collision frequency shift.

Cold collision frequency shifts and laser-cooled 87RB clocks

We demonstrate a Rb fountain clock which has a small cold collision shift that is cancelled by detuning the microwave cavity. We also demonstrate a juggling Rb clock and propose a novel quantum atom-optics precision scattering measurement for a juggling atomic clock. Finally we describe the design concept for RACE, a microgravity Rb clock for the ISS.

Juggling atomic clocks

We demonstrate a prototype of a laser-cooled 87Rb fountain clock and measure the frequency shift due to cold collisions. The shift is 30 times smaller than that in a laser-cooled Cs clock. We observe a density dependent pulling by the microwave cavity and use it to cancel the collision shift. We have also demonstrated a juggling atomic fountain to study cold collisions and we discuss the importance ofjuggling for future fountain clocks.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.