Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session U2: Invited Session: Hot TopicsInvited Undergraduate
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Chair: Steve Rolston, University of Maryland/JQI Room: Ballroom B |
Friday, May 27, 2016 10:30AM - 11:00AM |
U2.00001: Optoelectrical Cooling of Formaldehyde to Sub-Millikelvin Temperatures Invited Speaker: Martin Zeppenfeld Due to their strong long-range dipole-dipole interactions and large number of internal states, polar molecules cooled to ultracold temperatures enable fascinating applications ranging from ultracold chemistry to investigation of dipolar quantum gases. However, realizing a simple and general technique to cool molecules to ultracold temperatures, akin to laser cooling of atoms, has been a formidable challenge.\\ We present results for opto-electrical Sisyphus cooling applied to formaldehyde (H$_2$CO). In this generally applicable cooling scheme, molecules repeatedly move up and down electric field gradients of a trapping potential in different rotational states to efficiently extract kinetic energy\footnote{M. Zeppenfeld et al., Phys. Rev. A {\bf 80}, 041401(R) (2009).}. A total of about 300,000 molecules are thereby cooled by a factor of 1000 to 400uK, resulting in a record-large ensemble of ultracold molecules\footnote{A. Prehn et al., Phys. Rev. Lett. {\bf 116}, 063005 (2016).}. In addition to cooling of the motional degrees of freedom, optical pumping via a vibrational transition allows us to control the internal rotational state\footnote{R. Gl\"ockner et al., Phys. Rev. Lett. {\bf 115}, 233001 (2015).}. We thereby achieve a purity of over 80\% of formaldehyde molecules in a single rotational M-sublevel. Our experiment provides an excellent starting point for precision spectroscopy and investigation of ultracold collisions. [Preview Abstract] |
Friday, May 27, 2016 11:00AM - 11:30AM |
U2.00002: Quantum logic with molecular ions Invited Speaker: Piet O. Schmidt Precision spectroscopy is a driving force for the development of our physical understanding. However, only few atomic and molecular systems of interest have been accessible for precision spectroscopy in the past, since they miss a suitable transition for laser cooling and internal state detection. This restriction can be overcome in trapped ions through quantum logic spectroscopy [1]. Coherent laser manipulation originally developed in the context of quantum information processing with trapped ions allow the combination of the special spectroscopic properties of one ion species (spectroscopy ion) with the excellent control over another species (logic or cooling ion). I will show how the internal state of a molecular ion can be detected non-destructively on a co-trapped cooling ion by implementing a quantum logic algorithm involving only coherent laser manipulation on the molecular ion [2]. An optical dipole force tuned to near one of the molecule's resonances interacts with the molecular ion only if it is in a specific state. The resulting change in the motional state of a two-ion crystal formed by the molecular and atomic ion can be efficiently detected through the latter. More specifically, we detect if the MgH$^{\mathrm{+}}$ molecule is in the rotational state J$=$1 in the vibrational and electronic ground state. We observe quantum jumps into and out of this state that are driven by ambient black-body radiation. We use the detuning dependence of the dipole force to perform spectroscopy on an electronic transition. This represents a first step towards extending the exquisite control achieved over selected atomic species to much more complex molecular ions. [1] P. O. Schmidt, T. Rosenband, C. Langer, W. M. Itano, J. C. Bergquist, and D. J. Wineland, \textit{Spectroscopy Using Quantum Logic}, Science \textbf{309}, 749 (2005). [2] F. Wolf, Y. Wan, J. C. Heip, F. Gebert, C. Shi, and P. O. Schmidt, \textit{Non-destructive state detection for quantum logic spectroscopy of molecular ions}, Nature \textbf{530}, 457 (2016). [Preview Abstract] |
Friday, May 27, 2016 11:30AM - 12:00PM |
U2.00003: Long-Lived Spin Coherence in Ultracold NaK Molecules Invited Speaker: Huanqian Loh A trapped sample of ultracold polar molecules, where long-range anisotropic interactions can be tuned at will, offers rich possibilities for quantum information processing and for exploring novel Hamiltonians. For these applications, two important prerequisites must be fulfilled: the ability to manipulate single quantum states and long coherence times between the quantum states. In particular, a long coherence time translates to long information storage times and to precise measurements of energy levels for probing new physics. In this talk, we report on the microwave control of individual hyperfine levels in the lowest two rotational states of ultracold fermionic $^{23}$Na$^{40}$K molecules. Using Ramsey spectroscopy, we observe coherence times as long as 0.5 seconds between two nuclear spin states in the singlet rovibronic ground state. Upon decoherence, the mixture of two spin states remains fairly long lived, demonstrating the chemical stability of the $^{23}$Na$^{40}$K molecules against two-body collisions and may enable further evaporative cooling of the molecular sample. [Preview Abstract] |
Friday, May 27, 2016 12:00PM - 12:30PM |
U2.00004: Manipulation of quantum noise for precision measurements with cold atoms Invited Speaker: Onur Hosten I will focus on our experiments with cold atoms highlighting some of the most recent developments in the prospect of using quantum entanglement to improve the precision of atomic and optical sensors. The first part of the talk will describe the generation of 20dB spin-squeezed states of half a million $^{\mathrm{87}}$Rb atoms inside of an optical cavity. The second part will describe the experimental demonstration of a new concept we call quantum phase magnification. The demonstrated 20 dB squeezing enables a 100-fold reduction in averaging time or a 100-fold reduction in atom numbers to achieve a given sensing precision. As part of this work we show an atomic clock operating 10 dB beyond the classical limit. Some of the states prepared in these experiments possess in excess of 680 atom entanglement. The quantum phase magnification experiment shows that detection noise levels below the standard quantum limit is in fact not a requirement to realize the benefits of the intrinsic sensitivity provided by exotic quantum states. Here, optical cavity-aided effective interactions between atoms magnify signals to-be-measured to levels that can easily be detected with a rather inefficient fluorescence imaging system. The method relaxes stringent detection requirements which have been the main bottleneck in quantum metrology experiments, and can also be implemented in physical platforms other than cold atom-cavity systems. [Preview Abstract] |
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