Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session J06: Atomic Clocks |
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Chair: Christian Sanner, JILA Room: Grand G |
Wednesday, May 30, 2018 10:30AM - 10:42AM |
J06.00001: Imaging optical frequencies with 100 $\mu\mathrm{Hz}$ precision and 1.1 $\mu\mathrm{m}$ resolution Ross B. Hutson, G. Edward Marti, Akihisa Goban, Sara L. Campbell, Nicola Poli, Jun Ye We implement high resolution, optical spectroscopy and spatially resolved readout of a lattice-trapped Fermi-degenerate gas of strontium. Here, correlations in the atomic signal between different spatial regions of the sample enable the most rapid evaluation of lattice induced clock shifts and a record fractional frequency precision of $2.5 \times 10^{-19}$. Additionally, we discuss current limits to atomic coherence times in optical lattices and prospects for improving them. In future work, these techniques can be directly applied to studies of long-range-interacting atomic dipoles and tests of general relativity at the millimeter scale. [Preview Abstract] |
Wednesday, May 30, 2018 10:42AM - 10:54AM |
J06.00002: Two clock transitions in neutral Yb for the highest sensitivity to variations of fundamental constants Marianna Safronova, Sergey Porsev, Christian Sanner, Jun Ye We propose a new frequency standard based on a $4f^{14} 6s6p~ ^3\!P_0 - 4f^{13} 6s^2 5d ~(J=2)$ transition in neutral Yb. This transition has a potential for high stability and accuracy and the advantage of the highest sensitivity among atomic clocks to variation of the fine-structure constant $\alpha$. We find its dimensionless $\alpha$-variation enhancement factor to be $K=-15$, in comparison to the most sensitive current clock (Yb$^+$ E3, $K=-6$), and it is 18 times larger than in any neutral-atomic clocks (Hg, $K=0.8$). Combined with the unprecedented stability of an optical lattice clock for neutral atoms, this high sensitivity opens new perspectives for searches for ultralight dark matter and for tests of theories beyond the standard model of elementary particles. Moreover, together with the well-established $^1\!S_0 -\, ^3\!P_0$ transition one will have two clock transitions operating in neutral Yb, whose interleaved interrogations may further reduce systematic uncertainties of such clock-comparison experiments. [Preview Abstract] |
Wednesday, May 30, 2018 10:54AM - 11:06AM |
J06.00003: Ultracold Molecular Clock in a State-Insensitive Optical Lattice Chih-Hsi Lee, Stanimir Kondov, Christian Liedl, Kon H. Leung, Tanya Zelevinsky Techniques originally developed for atomic clocks can be adapted to ultracold molecules, with applications ranging from quantum-state-controlled ultracold chemistry to searches for new physics. We present recent experimental results on the $^{88}Sr_2$ molecular clock which allows us to test molecular QED, search for mass-dependent “fifth-force” interactions, and potentially probe the electron-to-proton mass ratio variations. The oscillator of such a molecular clock consists of the frequency difference between two vibrational levels in the electronic ground state. The transition between the levels is driven by a pair of Raman lasers via an off-resonant excited state. We have achieved transitions from weakly bound to multiple deeply bound ground states. Trap-insensitive spectroscopy is crucial for extending coherent molecule-light interactions. We have demonstrated the “magic wavelength” technique for molecules by manipulating the optical lattice frequency near narrow polarizability resonances. This technique allows us to increase the coherence time a thousandfold and to narrow the ~30 THz vibrational transition initially to ~100 Hz. Long coherence times of molecular state superpositions are useful not only for fundamental metrology but also for quantum information. [Preview Abstract] |
Wednesday, May 30, 2018 11:06AM - 11:18AM |
J06.00004: Progress Towards a $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ Optical Clock with a Fractional Uncertainty at the E-18 Level Hua Guan, Yao Huang, Kelin Gao As its simplicity on the laser system, $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ optical clock can be made a low-cost, compact, and robust optical clock. We built two $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ optical clocks in WIPM. Based upon the comparison of two $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ optical clocks, the frequency difference was measured to be 3.2E-17 with uncertainty of 5.5 E-17. And a fractional stability of 7 E-17 in 20,000 s of averaging time is achieved. (\textit{Y. Huang et al., Phys. Rev. Lett.116, 013001 (2016)}). In order to reduce the BBR effect caused by the differential static scalar polarizability $\Delta \alpha_{\mathrm{0}}$, we measured $\Delta \alpha_{\mathrm{0\thinspace }}$with high precision by the comparison of two clocks. And result is -7.2653(44) *10$^{\mathrm{40}}$ J m$^{\mathrm{2}}$/V$^{\mathrm{2}}$, 19 times better compared to the best atomic structure calculation. The contribution of the blackbody shift coefficient to the uncertainty of the optical clock at room temperature has been reduced to the E$-$19 level, the excess micromotion induced clock uncertainty is also reduced to the E$-$19 level by choosing the “\textit{magic}” trap drive frequency. With the above improvements made, the total clock uncertainty is reduced to 2.2 E-17, limited by the BBR field evaluation like most of the state-of-art ion or neutral atom optical clocks. [Preview Abstract] |
Wednesday, May 30, 2018 11:18AM - 11:30AM |
J06.00005: Plans and prospects for a multiplexed optical lattice clock Shimon Kolkowitz We will present a novel design for a multiplexed optical lattice clock. In contrast to other optical lattice clock configurations, this apparatus will allow for independent loading, preparation, and interrogation of two ensembles of strontium atoms in spatially separated, movable optical lattices. Simultaneous differential measurements of the two ensembles will offer common mode noise rejection of shared environmental perturbations and clock laser noise. We will propose new tests of relativity and methods for evaluating clock systematics using differential measurements, and discuss applications of a multiplexed optical lattice clock to gravitational wave detection and searches for beyond standard model physics. Finally, we will briefly discuss the prospects for harnessing the multiplexed optical lattice clock to develop quantum enhanced clocks and clock networks using Rydberg interactions. [Preview Abstract] |
Wednesday, May 30, 2018 11:30AM - 11:42AM |
J06.00006: Frequency stability of pulsed superradiant light from the strontium clock transition Juan A. Muniz, Matthew A. Norcia, Julia Cline, John Robinson, Ross Hutson, G. Edward Marti, Akihisa Goban, Jun Ye, James Thompson Superradiant aser light from an ultra-narrow optical transition has been proposed as a next-generation active atomic frequency reference. In this work, we present the first characterization of the spectral properties of superradiant pulses of light emitted from the millihertz linewidth optical clock transition in an ensemble of cold $^{87}$Sr atoms trapped inside an optical cavity (Norcia et. al. arXiv:1711.10407). The frequency of the superradiant light is compared to that of a state-of-the-art cavity-stabilized laser and passive strontium optical lattice clock. We characterize the stability and absolute accuracy, as well as demonstrate insensitivity to key environmental perturbations such as fluctuations in the bare optical cavity frequency and magnetic field. The high degree of insensitivity to changes in the cavity length implies that mirror thermal noise will have a negligible impact on the superradiant light frequency, and that the system is a good frequency reference candidate for operation in harsh environments. [Preview Abstract] |
Wednesday, May 30, 2018 11:42AM - 11:54AM |
J06.00007: Experimental progress of dual-wavelength good-bad cavity active optical clock. Tiantian Shi, Duo Pan, Xiaogang Zhang, Jingbiao Chen Active optical clock, first proposed in 2005, utilizing optical stimulated emission on ultranarrow clock transitions in bad cavity regime, is expected to realize mHz linewidth due to the influence of thermal vibrations of cavity mirrors on the emitted optical frequency can be greatly reduced, which is still a hurdle for current optical clocks. To obtain the theoretical quantum limitied linewidth, we proposed the dual-wavelength good-bad cavity active optical clock, of which Nd:YAG 1064 nm and Cs 1470 nm lasers share the same cavity and operate in good and bad cavity regime, respectively. The 1064 nm laser frequency is locked to a super cavity at subhertz with PDH technique to stabilize the cavity length, and the frequency stability of the 1470 nm ultimate laser is expected to be improved by 2 orders of magnitude than that of the PDH stabilized laser due to the cavity pulling suppression effect in bad cavity regime. Experimentally, we build two independent systems and demonstrate typical characteristics of the dual-wavelength signals. To further suppress the residual cavity pulling effect, we lock the two good cavity signals to each other to stabilize the cavity length and measure the frequency stability of ultimate laser by heterodying between the two systems. [Preview Abstract] |
Wednesday, May 30, 2018 11:54AM - 12:06PM |
J06.00008: Atomic properties of Lu$^+$ for a development of an optical clock. Sergey Porsev, Ulyana Safronova, Marianna Safronova The singly-ionized lutetium has a number of fortuitous properties well suited for clock applications. The highly forbidden $^1\!S_0 -\, ^3\!D_1$ $M1$ clock transition was studied in [1,2] and, in particular, it was shown that it has a very small blackbody radiation (BBR) shift [2]. In this work, we continue to study Lu$^+$ properties [3] relevant to a development of this optical clock, including static and dynamic polarizabilities, dynamic contribution to the BBR shift, $E1$, $E2$, and $M1$ transition probabilities. Our calculations also demonstrate that Lu$^+$ is a good candidate to search for variation of the fine-structure constant. The details of the calculations will be reported at the conference. [1] M. D. Barrett, New J. Phys. 17, 053024 (2015). [2] K. Arnold et al., Phys. Rev. A 92, 032108 (2015). [3] E. Paez et. al., Phys. Rev. A 93, 042112 (2016). [Preview Abstract] |
Wednesday, May 30, 2018 12:06PM - 12:18PM |
J06.00009: Systematic uncertainty evaluation of an $^{27}$Al$^{+}$ quantum-logic clock Samuel Brewer, Jwo-Sy Chen, David Hume, Aaron Hankin, Ethan Clements, Chin-Wen Chou, David Wineland, David Leibrandt A previous optical atomic clock based on quantum-logic spectroscopy of the $^1S_0$ $\longleftrightarrow$ $^3P_0$ transition of $^{27}$Al$^{+}$ reached a systematic uncertainty of $\delta \nu / \nu = 8.0 \times 10^{-18}$ \footnote{C.-W. Chou,{\it et. al.}, PRL, \textbf{104}, 070802 (2010)},\footnote{C.-W. Chou, Private Communication}. This uncertainty was dominated by environmental effects related to the traps used to confine the ions; i.e. time-dilation shifts due to motion of the ions in the trap and the blackbody radiation (BBR) shift due to elevated trap temperature. Improvements in a new trap have reduced excess micromotion and secular heating, making it possible to operate the clock near the three-dimensional motional ground state \footnote{J.-S. Chen, {\it et. al.}, PRL, \textbf{118}, 053002, (2017)}, and leading to a reduced time-dilation shift uncertainty. In addition, the operating temperature of the system has been lowered to reduce the BBR shift uncertainty. Here we present the systematic uncertainty evaluation of a new $^{27}$Al$^{+}$ quantum-logic clock based on this improved trap design. [Preview Abstract] |
Wednesday, May 30, 2018 12:18PM - 12:30PM |
J06.00010: Comparison of Two Sr Optical Lattice Clocks with $10^{-17}/\sqrt{\tau}$ Level Stability Eric Oelker, Lindsay Sonderhouse, Tobias Bothwell, Ross Hudson, Colin Kennedy, Edward Marti, Dhruv Kedar, Akihisa Goban, Sarah Bromley, Sara Campbell, John Robinson, William Milner, Shimon Kolkowitz, Christian Sanner, Dan Matai, Thomas Legero, Fritz Riehle, Uwe Sterr, Jun Ye I report on the use of a state-of-the-art ultrastable laser to improve the stability of the JILA 1D and 3D $^{87}$Sr lattice clocks. The ultrastable laser system utilizes a cryogenic Silicon reference cavity with a thermal noise limited instability of $4\times10^{-17}$. By performing an asynchronous comparison betweeen the two systems along with a self comparison of each clock individually we are able to rigorously determine the stability of both clocks. We infer a clock stability at the mid-$10^{-17}/\sqrt{\tau}$ level for our 1D system and high-$10^{-17}/\sqrt{\tau}$ level for our 3D system due to dead time associated with sample preparation. The 1D result represents a new record for a clock based on a single atomic ensemble. [Preview Abstract] |
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