The Standard Model of particle physics is known to be incomplete. Extensions to the Standard Model, such as weak-scale supersymmetry, posit the existence of new particles and interactions that are asymmetric under time reversal (T) and nearly always predict a small yet potentially measurable electron electric dipole moment (EDM), d(e), in the range of 10(-27) to 10(-30) e·cm. The EDM is an asymmetric charge distribution along the electron spin (S(→)) that is also asymmetric under T. Using the polar molecule thorium monoxide, we measured d(e) = (-2.1 ± 3.7stat ± 2.5syst) × 10(-29) e·cm. This corresponds to an upper limit of |d(e)| < 8.7 × 10(-29) e·cm with 90% confidence, an order of magnitude improvement in sensitivity relative to the previous best limit. Our result constrains T-violating physics at the TeV energy scale.

Atom interferometers are powerful tools for both measurements in fundamental physics and inertial sensing applications. Their performance, however, has been limited by the available interrogation time of freely falling atoms in a gravitational field. We realize an unprecedented interrogation time of 20 seconds by suspending the spatially-separated atomic wavepackets in a lattice formed by the mode of an optical cavity. Unlike traditional atom interferometers, this approach allows potentials to be measured by holding, rather than dropping, atoms. After seconds of hold time, gravitational potential energy differences from as little as microns of vertical separation generate megaradians of interferometer phase. This trapped geometry suppresses the phase sensitivity to vibrations by 3-4 orders of magnitude, overcoming the dominant noise source in atom-interferometric gravimeters. Finally, we study the wavefunction dynamics driven by gravitational potential gradients across neighboring lattice sites.Matter-wave interferometers with freely falling atoms have demonstrated the ability to precisely measure e.g., gravity [1] and fundamental constants [2,3], to test general relativity [4][5][6], and to search for new forces [7,8].A major obstacle to increasing their sensitivity, however, has been the limited time during which coherent, spatially-separated superpositions of atomic wave packets can be interrogated. Up to 2.3 seconds of interrogation time has been realized in a 10-meter atomic fountain [9], and several seconds of interrogation time are the target of experiments in fountains measuring hundreds of meters [10,11], zero-gravity planes [12], drop towers [13], sounding rockets [14], and the International Space Station [15][16][17]. Geometries that trap the interferometer in an optical lattice [18,19] have been explored, but attempts to date have suffered from dephasing in the trap.Here, we demonstrate 20 seconds of coherence in an atom interferometer held in an optical lattice, overcoming trap dephasing by using an optical cavity as a spatial mode-filter. After 20 seconds, sensitivity to vibrations is suppressed by 10 3 − 10 4 relative to traditional atomic gravimeters at the same sensitivity, due to the continuous accumulation of free evolution phase in the trapped wave packets. Trapping the interferometer allows for the sensitivity to be increased by extending interrogation times rather than wavepacket separations or free fall distances, reducing experimental complexity and potentially minimizing systematics.Our matter-wave interferometer builds upon the setup described previously in [7,20]. Cesium atoms are laser-cooled to ∼300 nK, prepared in the magneticallyinsensitive m F =0 state, and launched millimeters upwards into free fall (see Methods for details). In free fall, counter-propagating laser beams in the cavity manipulate the atomic trajectories. We stimulate two-photon Raman transitions between the hyperfine ground states of cesium, F = 3 and F = 4, imparting two photons' momenta to the atom with each lase...

STIRAP (Stimulated Raman Adiabatic Passage) is a powerful laser-based method, usually involving two photons, for efficient and selective transfer of population between quantum states. A particularly interesting feature is the fact that the coupling between the initial and the final quantum states is via an intermediate state even though the lifetime of the latter can be much shorter than the interaction time with the laser radiation. Nevertheless, spontaneous emission from the intermediate state is prevented by quantum interference. Maintaining the coherence between the initial and final state throughout the transfer process is crucial.STIRAP was initially developed with applications in chemical dynamics in mind. That is why the original paper of 1990 was published in The Journal of Chemical Physics. However, as of about the year 2000, the unique capabilities of STIRAP and its robustness with respect to small variations of some experimental parameters stimulated many researchers to apply the scheme in a variety of other fields of physics. The successes of these efforts are documented in this collection of articles. In Part A the experimental success of STIRAP in manipulating or controlling molecules, photons, ions or even quantum systems in a solid-state environment is documented. After a brief introduction to the basic physics of STIRAP, the central role of the method in the formation of ultra-cold molecules is discussed, followed by a presentation of how precision experiments (measurement of the upper limit of the electric dipole moment of the electron or detecting the consequences of parity violation in chiral molecules) or chemical dynamics studies at ultra-low temperatures benefit from STIRAP. Next comes the STIRAP-based control of photons in cavities followed by a group of three contributions which highlight the potential of the STIRAP concept in classical physics by presenting data on the transfer of waves (photonic, magnonic and phononic) between respective wave guides. The works on ions or ion-strings discuss options for applications e.g. in quantum information. Finally, the success of STIRAP in the controlled manipulation of quantum states in solid-state systems, which are usually hostile towards coherent processes, is presented, dealing with data storage in rare-earth ion doped crystals and in NV-centers or even in superconducting quantum circuits. The works on ions and those involving solid-state systems emphasize the relevance of the results for quantum information protocols.Part B deals with theoretical work including further concepts relevant for quantum information or invoking STIRAP for the manipulation of matter waves. The subsequent articles discuss experiments underway to demonstrate the potential of STIRAP for populating otherwise inaccessible high-lying Rydberg states of molecules, or controlling and cooling the translational motion of particles in a molecular beam or the polarization of angular momentum states. The series of articles concludes with a more speculative application of STIRAP i...

We recently set a new limit on the electric dipole moment of the electron (eEDM) (J Baron et al and ACME collaboration 2014 Science 343 269-272), which represented an order-of-magnitude improvement on the previous limit and placed more stringent constraints on many charge-parityviolating extensions to the standard model. In this paper we discuss the measurement in detail. The experimental method and associated apparatus are described, together with the techniques used to isolate the eEDM signal. In particular, we detail the way experimental switches were used to suppress effects that can mimic the signal of interest. The methods used to search for systematic errors, and models explaining observed systematic errors, are also described. We briefly discuss possible improvements to the experiment. 9 Note that the limit we report here uses an updated value for  = 78 eff GV cm −1 which is obtained by averaging the results from [29, 30]. 10 A detailed discussion of the sign convention for this Hamiltonian term is provided in section appendix A.3 1 states have very small magnetic moments [58] since the d 3 2 orbital valence electron serves to nearly cancel the magnetic moment of the s 1 2 orbital. The actual magnetic moment of H deviates from zero primarily because of mixing with other states [59]. We express ThO molecule states using the basis Wñ |Y J M , , , , where Y is the electronic state, J is the total angular momentum, M is the projection of J onto the laboratoryẑ-axis, and Ω 1 (V cm −1 ) −1 [67]; this permits full (>99%) polarisation of the state in small applied electric fields,   10 V cm −1 , allowing us to take full advantage of the huge  eff in ThO. The Ω-doublet structure is also useful in rejecting systematic errors since it allows for spectroscopic reversal of  µ -n eff by addressing different  states without reversing the applied electric field [68]. This is discussed in greater detail in section 5.4.The H state in ThO is metastable with a lifetime »1.8 ms [69], limiting our measurement time to t » 1 ms. We note that this is comparable to previous beam-based eEDM measurements where the atomic/molecular states used had significantly longer lifetimes [20,69,70]. 1 (V cm −1 ) −1 (black arrow/lines) is the expectation value of the molecular electric dipole moment in these states [60]. Additionally, a magnetic field   causes a Zeeman shift  m »-Mg z 1 B , with m p » -ǵ 2 6kHz 1 B G −1 (red arrow/lines) [59, 64]. A nonzero eEDM would result in an additional energy shift   »-M d e eff (blue arrow/lines) where  = -1 (+1) when the applied  field is (is not) reversed. The orientation of   eff (green arrows), the spin of the electron in the σ orbital (black arrow next to molecule), the external electric field  , and the external magnetic field   are shown relative to the laboratoryẑ direction which is oriented upwards on the page. Diagram not to scale. 11 Throughout the paper, we give numerical values of energies (with  = 1) in terms of angular frequencies by using the notation p´f 2 , where f ...

No abstract

The best upper limit for the electron electric dipole moment was recently set by the ACME collaboration. This experiment measures an electron spin-precession in a cold beam of ThO molecules in their metastable D H 3

We study experimentally chaos synchronization of nonlinear optoelectronic oscillators with time-delayed mutual coupling and self-feedback. Coupling three oscillators in a chain, we find that the outer two oscillators always synchronize. In contrast, isochronal synchronization of the mediating middle oscillator is found only when self-feedback is added to the middle oscillator. We show how the stability of the isochronal solution of any network, including the case of three coupled oscillators, can be determined by measuring the synchronization threshold of two unidirectionally coupled systems. In addition, we provide a sufficient condition that guarantees global asymptotic stability of the synchronized solution.

We describe an experiment that implements capacitance-voltage profiling on a reverse-biased Schottky barrier diode to determine the density of impurity dopants in its semiconductor layer as well as its built-in electric potential. Our sample is a commercially produced Schottky diode. Three different experimental setups, one using research-grade instrumentation, the other two using low-cost alternatives, are given and their results compared. In each of the low-cost setups, phase-sensitive detection required to measure the sample's capacitance is carried out using an inexpensive data acquisition (DAQ) device and a software program that implements a lock-in detection algorithm. The limitations of the DAQ device being used (e.g., restricted analog-to-digital conversion speed, inadequate waveform generation capabilities, lack of hardware triggering) are taken into account in each setup. Excellent agreement for the value of the doping density obtained by the all three setups is found and this value is shown to be consistent with the result of an independent method (secondary ion mass spectroscopy). V