Bichromatic UV detection system for atomically-resolved imaging of ions

We present a compact and bichromatic imaging system, located outside of the vacuum chamber of a trapped ion apparatus, that collects the fluorescence of 230.6 nm and 369.5 nm photons simultaneously on a shared EMCCD camera. The system contains two lens doublets, consisting of a sphere and an asphere. It provides a numerical aperture of 0.45 and 0.40 at 230.6 nm and 369.5 nm, respectively, and enables spatially resolved state detection with a large field of view of 300 $\mu$m for long $^{115}$In$^+$/$^{172}$Yb$^+$ Coulomb crystals. Instead of diffraction limited imaging for one wavelength, the focus in this system is on simultaneous single-ion resolved imaging of both species over a large field with special attention to the deep UV wavelength (230.6 nm) and the low scattering rate of In$^+$ ions. The introduced concept is applicable to other dual-species applications

Heat transport in a Coulomb ion crystal with a topological defect

The thermodynamics of low-dimensional systems departs significantly from phenomenologically deducted macroscopic laws. Particular examples, not yet fully understood, are provided by the breakdown of Fourier's law and the ballistic transport of heat. Low-dimensional trapped ion systems provide an experimentally accessible and well-controlled platform for the study of these problems. In our work, we study the transport of thermal energy in low-dimensional trapped ion crystals, focusing in particular on the influence of the Aubry-like transition that occurs when a topological defect is present in the crystal. We show that the transition significantly hinders efficient heat transport, being responsible for the rise of a marked temperature gradient in the non-equilibrium steady state. Further analysis reveals the importance of the motional eigenfrequencies of the crystal.Comment: 9 pages, 5 figure

Sub-kelvin temperature management in ion traps for optical clocks

The uncertainty of the ac Stark shift due to thermal radiation represents a major contribution to the systematic uncertainty budget of state-of-the-art optical atomic clocks. In the case of optical clocks based on trapped ions, the thermal behavior of the rf-driven ion trap must be precisely known. This determination is even more difficult when scalable linear ion traps are used. Such traps enable a more advanced control of multiple ions and have become a platform for new applications in quantum metrology, simulation and computation. Nevertheless, their complex structure makes it more difficult to precisely determine its temperature in operation and thus the related systematic uncertainty. We present here scalable linear ion traps for optical clocks, which exhibit very low temperature rise under operation. We use a finite-element model refined with experimental measurements to determine the thermal distribution in the ion trap and the temperature at the position of the ions. The trap temperature is investigated at different rf-drive frequencies and amplitudes with an infrared camera and integrated temperature sensors. We show that for typical trapping parameters for $\mathrm{In}^{+}$, $\mathrm{Al}^{+}$, $\mathrm{Lu}^{+}$, $\mathrm{Ca}^{+}$, $\mathrm{Sr}^{+}$ or $\mathrm{Yb}^{+}$ ions, the temperature rise at the position of the ions resulting from rf heating of the trap stays below 700 mK and can be controlled with an uncertainty on the order of a few 100 mK maximum.Comment: 18 page

Atomic clocks with suppressed blackbody radiation shift

We develop a nonstandard concept of atomic clocks where the blackbody radiation shift (BBRS) and its temperature fluctuations can be dramatically suppressed (by one to three orders of magnitude) independent of the environmental temperature. The suppression is based on the fact that in a system with two accessible clock transitions (with frequencies v1 and v2) which are exposed to the same thermal environment, there exists a "synthetic" frequency v_{syn} (v1-e12 v2) largely immune to the BBRS. As an example, it is shown that in the case of ion 171Yb+ it is possible to create a clock in which the BBRS can be suppressed to the fractional level of 10^{-18} in a broad interval near room temperature (300\pm 15 K). We also propose a realization of our method with the use of an optical frequency comb generator stabilized to both frequencies v1 and v2. Here the frequency v_{syn} is generated as one of the components of the comb spectrum and can be used as an atomic standard.Comment: 5 pages, 2 figure