arXiv subjects

A Guttridge

Publications and source records attributed to A Guttridge.

3 recordsLinked to original sources

arXiv2022

Feshbach Spectroscopy of Cs Atom Pairs in Optical Tweezers

We prepare pairs of $^{133}$Cs atoms in a single optical tweezer and perform Feshbach spectroscopy for collisions of atoms in the states $(f=3, m_f=\pm3)$. We detect enhancements in pair loss using a detection scheme where the optical tweezers are repeatedly subdivided. For atoms in the state $(3,-3)$, we identify resonant features by performing inelastic loss spectroscopy. We carry out coupled-channel scattering calculations and show that at typical experimental temperatures the loss features are mostly centred on zeroes in the scattering length, rather than resonance centres. We measure the number of atoms remaining after a collision, elucidating how the different loss processes are influenced by the tweezer depth. These measurements probe the energy released during an inelastic collision, and thus give information on the states of the collision products. We also identify resonances with atom pairs prepared in the absolute ground state $(f=3, m_f=3)$, where two-body radiative loss is engineered by an excitation laser blue-detuned from the Cs D$_2$ line. These results demonstrate optical tweezers to be a versatile tool to study two-body collisions with number-resolved detection sensitivity.

physics.atom-ph↗

arXiv2021

Preparation of one $^{87}$Rb and one $^{133}$Cs atom in a single optical tweezer

We report the preparation of exactly one $^{87}$Rb atom and one $^{133}$Cs atom in the same optical tweezer as the essential first step towards the construction of a tweezer array of individually trapped $^{87}$Rb$^{133}$Cs molecules. Through careful selection of the tweezer wavelengths, we show how to engineer species-selective trapping potentials suitable for high-fidelity preparation of Rb $+$ Cs atom pairs. Using a wavelength of 814~nm to trap Rb and 938~nm to trap Cs, we achieve loading probabilities of $0.508(6)$ for Rb and $0.547(6)$ for Cs using standard red-detuned molasses cooling. Loading the traps sequentially yields exactly one Rb and one Cs atom in $28.4(6)\,\%$ of experimental runs. Using a combination of an acousto-optic deflector and a piezo-controlled mirror to control the relative position of the tweezers, we merge the two tweezers, retaining the atom pair with a probability of $0.99^{(+0.01)}_{(-0.02)}$. We use this capability to study hyperfine-state-dependent collisions of Rb and Cs in the combined tweezer and compare the measured two-body loss rates with coupled-channel quantum scattering calculations.

physics.atom-ph↗

arXiv2016

Direct loading of a large Yb MOT on the $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition

We report a robust technique for laser frequency stabilisation that enables the reproducible loading of in excess of 10$^{9}$ Yb atoms from a Zeeman slower directly into a magneto-optical trap (MOT) operating on the $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition, without the need for a first stage MOT on the $^{1}S_{0} \rightarrow \, ^{1}P_{1}$ transition. We use a simple atomic beam apparatus to generate narrow fluorescence signals on both the 399 nm $^{1}S_{0} \rightarrow \, ^{1}P_{1}$ transition used for the Zeeman slower and the 556 nm $^{1}S_{0} \rightarrow \, ^{3}P_{1}$ transition. We present in detail the methods for obtaining spectra with a high signal-to-noise ratio and demonstrate error signals suitable for robust frequency stabilisation. Finally we demonstrate the stability and precision of our technique through sensitive measurements of the gravitational sag of the Yb MOT as a function of the intensity of the laser cooling beams, which are in good agreement with theory. These results will be important for efficient loading of the atoms into an optical dipole trap.

physics.atom-ph↗