Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session P07: Atomic ClocksLive
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Chair: Andrew Ludlow, NIST Room: E145-146 |
Thursday, June 4, 2020 2:00PM - 2:12PM Live |
P07.00001: Towards suppression of light shifts in an optical frequency standard based on a two-photon transition in Rb Joseph Christesen, Zachary Newman, Valera Yudin, John Kitching, Matthew Hummon Low power and compact optical frequency standards based on atomic references are widely used in a number of different applications including length metrology, laser ranging, optical communication, and timing. These systems are now at levels of stability where a major limiting factor is the ac-Stark shift. While other atomic systems can use a Ramsey type scheme to eliminate the light shift, frequency standards which operate in a continuous wave (CW) mode need another method. To this end, we look to implement two new schemes, combined error signal (CES) and auto-compensation shift (ACS), based on a recent theoretical proposal to eliminate the ac-Stark shift in an optical frequency standard [1]. The CES scheme is a single loop scheme where a new error signal is generated which has its zero crossing at the frequency where the ac-Stark shift is zero, and the ACS scheme is a double loop scheme where the second loop produces an artificial anti-shift to compensate the ac-Stark shift. We investigate the experimental challenges in implementing the CES and ACS and show progress towards improving the long-term stability of an optical frequency standard based on the two-photon transition at 778 nm in $^{\mathrm{87}}$Rb through suppression of the ac-Stark shift. [1] V. I. Yudin, et al., arXiv: 1911.02935 [Preview Abstract] |
Thursday, June 4, 2020 2:12PM - 2:24PM Live |
P07.00002: Driving the optical clock transition in Ra$^{+}$ Craig A. Holliman, Mingyu Fan, Andrew M. Jayich Radium is an intriguing candidate for a trapped ion optical clock due to its high mass and favorable wavelengths$-$the cooling transition at 468 nm is far from the UV. The $S_{1/2} \rightarrow D_{5/2}$ transition at 728 nm has a sub-Hz natural linewidth, making it suitable for an optical clock transition. We report driving and frequency measurements of the radium ion's clock transition as well as the other narrow electric quadrupole transition from the $S_{1/2}$ to $D_{3/2}$ state. We also report measurements of the 802 nm $D_{5/2} \rightarrow P_{3/2}$ cleanout transition frequency, as well as the frequencies of other low-lying transitions in Ra$^{+}$. [Preview Abstract] |
Thursday, June 4, 2020 2:24PM - 2:36PM Live |
P07.00003: Higher-order lattice light shifts in the Cd optical clock Sergey Porsev, Marianna Safronova The $5s^2\,^1\!S_0 -\, 5s5p\, ^3\!P^o_0$ transition in cadmium is an attractive candidate for an optical lattice clock because it allows for an efficient narrow-line cooling and has a small sensitivity to blackbody radiation~[1], the effect which dominates the uncertainty budget of Sr and Yb clocks. Two isotopes of Cd have a nuclear spin of 1/2, which precludes tensor light shifts from the lattice light, another advantageous feature. In this work we address the problem of higher-order lattice light shifts in the Cd clock caused by the multipolar $M1$ and $E2$ atom-field interactions and by the term nonlinear in lattice intensity and determined by the hyperpolarizability. Using the method that combines configuration interaction and linearized coupled-cluster single double method we found the magnetic dipole and electric quadrupole polarizabilities and hyperpolarizabilities at the magic wavelength of the $^1\!S_0$ and $^3\!P^o_0$ states and determined these quantities for the clock transition frequency. The results are compared with those for the $5s^2\,^1\!S_0 -\, 5s5p\, ^3\!P^o_0$ Sr clock transition. \\ \noindent [1] A.~Yamaguchi, M.~S.~Safronova, K.~Gibble, and H.~Katori, Phys. Rev. Lett. {\bf 123}, 113201 (2019) [Preview Abstract] |
Thursday, June 4, 2020 2:36PM - 2:48PM Live |
P07.00004: Accurate prediction of clock transitions in a highly charged ion with complex electronic structure Charles Cheung, Marianna Safronova, Sergey Porsev, Mikhail Kozlov, Ilya Tupitsyn, Andrey Bondarev We have developed a broadly-applicable approach that drastically increases the ability to accurately predict properties of complex atoms. We applied it to the case of Ir$^{17+}$, which is of particular interest for the development of novel atomic clocks with high sensitivity to the variation of the fine-structure constant and dark matter searches. The clock transitions are weak and very difficult to identity without accurate theoretical predictions. In the case of Ir$^{17+}$, even stronger electric-dipole ($E1$) transitions eluded observation despite years of effort raising the possibility that theory predictions are grossly wrong. In this work, we provide accurate predictions of transition wavelengths and $E1$ transition rates in Ir$^{17+}$. Our results explain the lack of observation of the $E1$ transitions and provide a pathway towards detection of clock transitions. Computational advances demonstrated in this work are widely applicable to most elements in the periodic table and will allow to solve numerous problems in atomic physics, astrophysics, and plasma physics. [Preview Abstract] |
Thursday, June 4, 2020 2:48PM - 3:00PM Live |
P07.00005: Lifetime-limited Coherence Between Two $^{27}$Al$^+$ Clocks using Correlation Spectroscopy Ethan Clements, May Kim, Kaifeng Cui, Aaron Hankin, Samuel Brewer, Jwo-Sy Chen, David Leibrandt, David Hume In optical clock comparisons, measurement stability is often limited by the coherence time of the local oscillator. Correlation spectroscopy is a technique for performing frequency measurements between two atomic clocks with an interrogation time beyond this limit[1-3]. By interrogating with the same local oscillator and measuring correlations in the atomic states, the common-mode phase noise of the local oscillator is removed. Here, we demonstrate correlation spectroscopy between two independent $^{27}$Al$^+$ optical clocks. We observe coherence between the two systems (operating at a frequency of $1.121$ PHz) with interrogation times up to 8s, beyond the capability of state-of-the-art cavity-stabilized lasers[4]. This increase in the interrogation time requires active control of differential noise sources such as magnetic field noise and optical-path-length fluctuations. We obtain a fractional comparison measurement instability below $4 \times 10^{-16}/\sqrt{\tau}$ where $\tau$ is the averaging time, a factor of $\sim$10 improvement from previous Al$^+$ clock comparisons. [1]M. Chwalla et al., APB, 89, 483, (2007) [2]S. Olmschenk et al., PRA, 76, 052314, (2007) [3]C.W. Chou et al., PRL, 106, 160801, (2011) [4]D.G.Matei et al., PRL, 118, 263202, (2017) [Preview Abstract] |
Thursday, June 4, 2020 3:00PM - 3:12PM Live |
P07.00006: Building Spin-Squeezed Optical Lattice Clock Chi Shu, Edwin Pedrozo, Simone Colombo, Albert Adiyatullin, Zeyang Li, Enrique Mendez, Akio Kawasaki, Boris Braverman, Vladan Vuletic Quantum enhanced metrology promises a significant boost of the performance of sensors with a precision that surpass classical limit and enables possibilities of new generation of sensors with unprecedented sensitivity. We generate and characterize a spin-squeezed state on the optical clock transition in $^{171}$Yb by combination of cavity feedback squeezing and optical state transfer. The observed precision gain over standard quantum limit (SQL) is 4.4dB. The demonstration paves the path to improve the optical lattice clocks (OLC) beyond current records stability of $5×10^{-17}/\sqrt{τ}$, which is limited by quantum projection noise. [Preview Abstract] |
Thursday, June 4, 2020 3:12PM - 3:24PM On Demand |
P07.00007: Frequency reference for Nanosatellite Quantum technology mission Sapam Ranjita Chanu, Aaron Strangfeld, Markus Krutzik, Alexander Ling We report on our latest progress on the ongoing development of a compact optical frequency reference for CubeSat missions in LEO. The reference will be based on Doppler free laser spectroscopy of rubidium vapor. Our simplified solution is based on frequency modulation spectroscopy using a customized, shielded 5 mm long vapor cell and a monolithic distributed feedback (DFB) laser diode on a mesoscopic breadboard setup. The electro-optical system features miniaturized optics as well as a polarization maintaining fiber coupling inside a housing with dimensions of 70 mm $\times$ 25 mm $\times$ 25 mm. The latter will be installed on a 100 mm $\times$ 100 mm $\times$ 100 mm electronics board for full functionality of the system. This way, our reference constitutes a key technology for future compact, simple and robust atomic quantum technologies for nanosatellite applications, e.g. inertial sensors or clocks. [Preview Abstract] |
Thursday, June 4, 2020 3:24PM - 3:36PM Not Participating |
P07.00008: Modeling lattice light shifts in optical lattice clocks Kyle Beloy, William McGrew, Xiaogang Zhang, Daniele Nicolodi, Robert Fasano, Youssef Hassan, Roger Brown, Andrew Ludlow Optical lattice clocks rely on a strong perturbation to the atoms for atomic confinement. Within the optical lattice, the atomic levels are light-shifted by an amount $\gtrsim\!10^{-10}$ times the clock frequency. While clock performance has steadily improved over the years, with fractional inaccuracies at the low-$10^{-18}$ level now being realized, lattice light shifts have invariably been a dominant item in the uncertainty budgets. To realize new levels of clock performance, better theoretical models will be required for characterizing the lattice light shifts. Here we present a new model developed for this purpose. [Preview Abstract] |
Thursday, June 4, 2020 3:36PM - 3:48PM |
P07.00009: Progress on lattice light shift evaluations in the JILA 1D strontium optical lattice clock Tobias Bothwell, Colin Kennedy, John Robinson, Eric Oelker, Josephine Meyer, William Milner, Dhruv Kedar, Jun Ye We have rebuilt the JILA Sr1 optical lattice clock including an intra-vacuum build-up optical cavity for a 1D lattice. The system is designed for robust operation to support an all-optical time scale, and to advance the state-of the-art in lattice clock performance. The design goals include clock stability better than 3x10$^{\mathrm{-17}}$ at 1 s, and clock uncertainty better than 1x10$^{\mathrm{-18}}$. In this talk we will report on our progress evaluating lattice light shifts in this system and will discuss our work on reporting the necessary atomic coefficients for improved accuracy. [Preview Abstract] |
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