Absorption of light is a fundamental process in imaging. The optical properties of atoms are thoroughly understood, so a
single atom is an ideal system for testing the quantum limits of absorption imaging. Here we report the first absorption
imaging of a single isolated atom, the smallest and simplest system reported to date. Contrasts of up to 3.1(3)% were
observed in images of a laser cooled <sup>174</sup>Yb<sup>+</sup> ion confined in vacuum by a radio-frequency Paul trap. This work
establishes a new sensitivity bound for absorption imaging with a 7800x improvement over the contrast previously
observed in imaging a single molecule.
We developed techniques to design higher efficiency diffractive optical elements (DOEs) with large
numerical apertures (NA) for quantum computing and quantum information processing. Large NA optics
encompass large solid angles and thus have high collection efficiencies. Qubits in ion trap architectures are
commonly addressed and read by lasers<sup>1</sup>. Large-scale ion-trap quantum computing<sup>2</sup> will therefore require
highly parallel optical interconnects. Qubit readout in these systems requires detecting fluorescence from
the nearly isotropic radiation pattern of single ions, so efficient readout requires optical interconnects with
high numerical aperture. Diffractive optical element fabrication is relatively mature and utilizes
lithography to produce arrays compatible with large-scale ion-trap quantum computer architectures. The
primary challenge of DOEs is the loss associated with diffraction efficiency. This is due to requirements
for large deflection angles, which leads to extremely small feature sizes in the outer zone of the DOE. If
the period of the diffractive is between &lgr; (the free space wavelength) and 10&lgr;, the element functions in the
vector regime. DOEs in this regime, particularly between 1.5&lgr; and 4&lgr;, have significant coupling to
unwanted diffractive orders, reducing the performance of the lens. Furthermore, the optimal depth of the
zones with periods in the vector regime differs from the overall depth of the DOE. We will present results
indicating the unique behaviors around the 1.5&lgr; and 4&lgr; periods and methods to improve the DOE
performance.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print format on
SPIE.org.