Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session S03: Atomic ClocksLive
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Chair: May Kim, National Institute of Standards and Technology Boulder |
Thursday, June 3, 2021 10:30AM - 10:42AM Live |
S03.00001: A 1D Strontium Optical Lattice Clock With Record Low Intrinsic Instability Tobias Bothwell
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Thursday, June 3, 2021 10:42AM - 10:54AM Live |
S03.00002: Enhanced Differential Stability Measurements with a Multiplexed Strontium Optical Lattice Clock Jonathan C Dolde, Xin Zheng, Varun Lochab, Brett N Merriman, Haoran Li, Shimon Kolkowitz The extremely high precision of optical lattice clocks enable their use in novel tests of fundamental physics. Currently, one of the primary factors limiting optical lattice clock performance is the coherence of the clock laser, with only a handful of highly specialized clock lasers in the world operating with linewidths approaching the natural line width of 87Sr’s clock transition (~1 mHz). In this talk, we will present our implementation of a multiplexed Sr optical lattice clock that overcomes the limitations imposed by clock laser coherence by utilizing synchronous differential measurements between multiple ensembles of ultra-cold, neutral 87Sr atoms held in spatially separated regions of an optical lattice. We report atom-atom Ramsey coherence times exceeding 10 seconds with a ~1 Hz linewidth clock laser, and differential stabilities below 3×10−17/√τ obtained by synchronous Ramsey interrogation of two ensembles. Lastly, we will discuss on-going and planned applications of the multiplexed optical lattice clock to tests of relativity, including measurements of the gravitational redshift at the sub-cm scale and studies of the special relativistic effects of accelerations on clocks. |
Thursday, June 3, 2021 10:54AM - 11:06AM Live |
S03.00003: Toward a spin-squeezed strontium optical lattice clock with state-of-the-art stability John M Robinson, Maya Miklos*, Yee Ming Tso, Josephine Meyer, Colin J Kennedy, Tobias Bothwell, James K Thompson, Jun Ye
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Thursday, June 3, 2021 11:06AM - 11:18AM Live |
S03.00004: Continuous superradiant laser based on a simple hot atomic beam Sheng Zhou, Francesca Fama, Camila Beli Silva, Mikkel Tang, Zeyuan Zhang, Stefan Alaric Schäffer, Chun-Chia Chen, Benjamin Pasquiou, Shayne Bennetts, Florian Schreck We will report on our recent work that aims to experimentally demonstrate continuous superradiance on the 1S0-3P1 transition of 88Sr. Our approach employs a simple architecture based on a hot atomic beam of excited atoms passing through a cavity that was recently proposed [1,2]. Superradiant lasing in the bad-cavity regime decreases cavity pulling reducing sensitivity to environmental perturbations. Due to the promise of cavity noise suppression, superradiant lasers have been proposed as a next generation optical frequency reference for atomic clocks [3]. |
Thursday, June 3, 2021 11:18AM - 11:30AM Live |
S03.00005: A Rugged mHz-Linewidth Superradiant Laser Driven by a Hot Atomic Beam Haonan Liu, Simon B Jäger, Xianquan Yu, Steven Touzard, Athreya Shankar, Travis L Nicholson, Murray J Holland We propose a continuous-wave, ultracoherent laser based on superradiance from a hot atomic beam traversing an optical cavity. Its predicted minimum linewidth and maximum output power are competitive with the best narrow-linewidth light sources. We show that, because of atomic phase synchronization, the phase of the output light is robust against decoherence arising from atomic motion, such as transit time broadening and Doppler broadening, as well as spontaneous emission and $T_2$ dephasing. Additionally, the system is inherently insensitive to effects that limit the best stable lasers, such as environmental noise and frequency drift. We believe the simplicity and ruggedness of our design will make it well suited for wide laboratory use, operation in challenging environments, and possibly serving as an active atomic clock. |
Thursday, June 3, 2021 11:30AM - 11:42AM Live |
S03.00006: Reducing Frequency Ratio Measurement Instability with Differential Spectroscopy Ethan R Clements, May E Kim, William McGrew, Nicholas V Nardelli, Youssef Hassan, Xiaogang Zhang, Jose L Valencia, David B Hume, Tara Fortier, Andrew D Ludlow, David Leibrandt Differential spectroscopy is a protocol for performing interspecies frequency ratio measurements with an instability beyond the limit set by laser noise. This protocol allows for probe durations exceeding the limit set by laser coherence for one or both clocks [1]. In this talk, we present an experimental demonstration of differential spectroscopy between a 171Yb lattice clock and a 27 Al+ quantum-logic clock. An Er/Yb-glass free-space optical frequency comb is used to transfer the laser phase of the 171Yb local oscillator at 518 THz to the 27Al+ local oscillator at 1.12 PHz. Synchronous Ramsey interrogations are performed and the common-mode laser phase is first measured by the 171Yb clock and subsequently fed-forward to the 27Al+ clock before the conclusion of its Ramsey sequence, enabling operation of the 27Al+ clock beyond its laser coherence time. The 27Al+ probe duration is further extended to an integer multiple of the 171Yb probe duration using a second 171Yb lattice clock to make zero dead time phase measurements [2]. We achieve fractional measurement instabilities below 2 × 10-16/τ1/2 with a probe duration of 1.7 s. This measurement instability will allow comparisons with a fractional ratio resolution of 10-18 in under 12 hours. |
Thursday, June 3, 2021 11:42AM - 11:54AM Live |
S03.00007: Towards a composite 171Yb+- 88Sr+ optical clock Martin R Steinel, Hu Shao, Melina Filzinger, Richard Lange, Nils Huntemann, Tanja Mehlstäubler, Ekkehard Peik The yearlong excited state lifetime of the electric octupole (E3) transition of 171Yb+ promises very long coherent laser interrogation. Motional heating of the trapped ions and laser noise, however, limit the resolvable linewidth and consequently the frequency stability of this clock transition so far. An ancillary 88Sr+ ion can provide sympathetic cooling of 171Yb+ during the interrogation on the E3 transition without introducing major frequency shifts from the sideband cooling lasers. Another important limitation for long coherent interrogation results from collisions of the reference ion with background gas molecules. To estimate the background pressure at the ion position, we determine the reorder rate of two-species ion crystals. In addition to its use as a cooling partner, the co-trapped 88Sr+ ion can be employed to in situ determine the thermal radiation field causing the largest frequency shift for most optical clocks at room temperature. In preparation for the combined clock operation, we measure the frequency ratio of the 88Sr+ and the 171Yb+ E3 clock transitions with 3*10-16 uncertainty. |
Thursday, June 3, 2021 11:54AM - 12:06PM Live |
S03.00008: Toward direct VUV frequency comb spectroscopy of the 229mTh nuclear state Chuankun Zhang, Lars von der Wense, Peng Li, Jie Jiang, Martin E Fermann, Jun Ye Recent breakthroughs searching for the low-energy 229mTh isomeric state have constrained its energy range to 8.12 ± 0.11 eV, within the reach of state-of-the-art VUV frequency combs. Direct VUV frequency comb spectroscopy of the 229mTh isomeric state in the ongoing experiment at JILA promises a further reduction of its energy uncertainty by 6 orders of magnitude, making it possible to develop a nuclear-based optical clock. In neutral atoms, the 229mTh state decays dominantly via the internal-conversion channel with a lifetime of about 10 us. Using this decay channel, we designed our experiment for optical excitation of the isomeric state on a thin (10 nm) 229Th layer deposited on a metallic substrate irradiated by the JILA VUV frequency comb. We will present our progress in this experimental effort. |
Thursday, June 3, 2021 12:06PM - 12:18PM Live |
S03.00009: Search for monopole-dipole interactions at the millimeter range Yukun Feng, Denghui Ning, Shaobo Zhang, Zhengtian Lu, Dong Sheng Monopole-dipole interactions involve scalar couplings between spin and massive particles. Such interactions violate P- and T-symmetry, and can be transmitted by axions. A 129Xe-131Xe-Rb comagnetometer is used to measure the ratio of precession frequencies between the two Xe isotopes, and search for changes of the ratio correlated with the distance between a nonmagnetic BGO crystal and the atomic cell. The search is sensitive to the monopole-dipole coupling at the millimeter range. Currently the statistical error of the frequency ratio measurement has reached the level of 10-7 with a bias field of 10 mG. |
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