Stark shift of the A2Π1/2A^2\Pi_{1/2} state in 174^{174}YbF

We have measured the Stark shift of the $A^2\Pi_{1/2} - X^2\Sigma^+$ transition in YbF. We use a molecular beam triple resonance method, with two laser transitions acting as pump and probe, assisted by an rf transition that tags a single hyperfine transition of the X state. After subtracting the known ground state Stark shift, we obtain a value of $70.3(1.5)$Hz/(V/cm)$^2$ for the static electric polarizability of the state $A^2\Pi_{1/2}(J=1/2,f)$. From this we calculate a value $\mu_e=2.46(3)$D for the electric dipole moment of the $A^2\Pi_{1/2}(v=0)$ state.Comment: 3 pages, 2 figure

Towards a new measurement of the electron's electric dipole moment

We present our progress towards a new measurement of the electron electric dipole moment using a beam of YbF molecules. Data are currently being taken with a sensitivity of 10^{-27} e.cm / \sqrt{day}

Ultra-sensitive atom imaging for matter-wave optics

Quantum degenerate Fermi gases and Bose-Einstein condensates give access to a vast new class of quantum states. The resulting multiparticle correlations place extreme demands on the detection schemes. Here we introduce diffractive dark-ground imaging as a novel ultra-sensitive imaging technique. Using only moderate detection optics, we image clouds of less than 30 atoms with near-atom shot-noise-limited signal-to-noise ratio and show Stern-Gerlach separated spinor condensates with a minority component of only seven atoms. This presents an improvement of more than one order of magnitude when compared to our standard absorption imaging. We also examine the optimal conditions for absorption imaging, including saturation and fluorescence contributions. Finally, we discuss potentially serious imaging errors of small atom clouds whose size is near the resolution of the optics