Daniel S. Barker

Development of a new UHV/XHV pressure standard (cold atom vacuum standard)

The National Institute of Standards and Technology has recently begun a program to develop a primary pressure standard that is based on ultra-cold atoms, covering a pressure range of 1 × 10-6 Pa to 1 × 10-10 Pa and possibly lower. These pressures correspond to the entire ultra-high vacuum (UHV) range and extend into the extreme-high vacuum (XHV). This cold-atom vacuum standard (CAVS) is both a primary standard and absolute sensor of vacuum. The CAVS is based on the loss of cold, sensor atoms (such as the alkali-metal lithium) from a magnetic trap due to collisions with the background gas (primarily H2) in the vacuum. The pressure is determined from a thermally-averaged collision cross section, which is a fundamental atomic property, and the measured loss rate. The CAVS is primary because it will use collision cross sections determined from ab initio calculations for the Li + H2 system. Primary traceability is transferred to other systems of interest using sensitivity coefficients.

Three-photon process for producing a degenerate gas of metastable alkaline-earth-metal atoms

We present a method for creating a quantum degenerate gas of metastable alkaline-earth atoms. This has yet to be achieved due to inelastic collisions that limit evaporative cooling in the metastable states. Quantum degenerate samples prepared in the

Note: A 3D-printed alkali metal dispenser

^{1}S_{0}

Vacuum furnace for degassing stainless-steel vacuum components

ground state can be rapidly transferred to either the

Review Article: Quantum-based vacuum metrology at the National Institute of Standards and Technology

^{3}P_{2}

An ultra-low noise, high-voltage piezo-driver

or

Enhanced Magnetic Trap Loading for Atomic Strontium

^{3}P_{0}

Quantum-based vacuum metrology at NIST

state via a coherent 3-photon process. Numerical integration of the density matrix evolution for the fine structure of bosonic alkaline-earth atoms shows that transfer efficiencies of

Perspectives for a new realization of the pascal by optical methods

\simeq90\%

A 3D-printed alkali metal dispenser

can be achieved with experimentally feasible laser parameters in both Sr and Yb. Importantly, the 3-photon process can be set up such that it imparts no net momentum to the degenerate gas during the excitation, which will allow for studies of metastable samples outside the Lamb-Dicke regime. We discuss several experimental challenges to successfully realizing our scheme, including the minimization of differential AC Stark shifts between the four states connected by the 3-photon transition.