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Results of the 2016 CAP Best Student Paper Competition (Divisions and CAP overall, oral and poster)
Congratulations! If you haven't received your prize confirmation letter at the Recognition Gala, June 16, please contact Danielle at capmgr@uottawa.ca.
Click on the "Timetable" on the left to view the Congress program.
The 2016 CAP Congress is being hosted by the University of Ottawa (Ottawa, ON), June 13-17, 2016. This Congress is an opportunity to showcase and celebrate the achievements of physicists in Canada and abroad. Mark your calendars and bookmark the main Congress web site (http://www.cap.ca/en/congress/2016 ) for easy access to updates and program information.
Félicitations! Si vous n'avez pas reçu votre lettre de confirmation de prix au Gala de reconnaissance du 16 juin, veuillez communiquer avec Danielle au capmgr@uottawa.ca
Cliquez sur "Timetable" à gauche pour voir la programmation du Congrès.
Le Congrès 2016 de l'ACP se tiendra à l'Université d'Ottawa (Ottawa, ON) du 13 au 17 juin 2016 (des réunions de l'IPP, l'IPCN et du conseil de l'ACP auront lieu le dimanche 12 juin). Au cours de cet événement nous pourrons profiter des présentations et des réalisations de physiciens et physiciennes du Canada et d'ailleurs, et les célébrer. Inscrivez la date du congrès à votre agenda et créez un signet de l'adresse du site web du congrès http://www.cap.ca/fr/congres/2016) pour accéder facilement aux mises à jour et au contenu de la programmation.
30 min presentation + 5 min questions
20 min presentation + 5 min questions
30 min presentation + 5 min questions
20 min presentation + 5 min questions
30 min presentation + 15 min questions
Monte Carlo simulations have been ubiquitous in efforts to simulate and characterize properties of matter and materials since the advent of computers themselves. In the last decade, condensed matter physicists have turned simulation technology to the study of a new set of phenomena, loosely termed as "emergent", with correlations not manifested in traditional correlation functions. Motivated by this, a new set of tools was recently developed that allows one to probe emergent phenomena in Monte Carlo simulations through their entanglement entropy - a concept borrowed from quantum information theory. Remarkably, since certain scaling terms in the entanglement entropy are universal, this provides a powerful general method to characterize phases and phase transitions in a wide variety of physical theories. Thus, Monte Carlo simulations are beginning to play a central role for physicists who increasingly rely on information quantities to study correlations not only in condensed matter systems and quantum devices, but even in quantum fields and theories of quantum gravity.
NEMA (National Electrical Manufacturers Association) Standard Measurements are used for evaluating the performance of the positron emission tomography scanners used in animal imaging. There are various measurements, including spatial resolution, scatter fraction, sensitivity, and image quality.
In this study the effects of varying the testing procedures of the NEMA NU4-2008 standard for measuring sensitivity and image quality for a small animal PET scanner were examined. In the current NEMA NU4 2008 standard, the sensitivity is measured by stepping a Na-22 point source through the field of view of the scanner along the central Z axis. In some scanners it is not possible to automate the collection of this data, making it very tedious, if not impossible, to acquire the necessary data. As an alternative method, we explore using a long uniform line source extended beyond the field of view in the axial direction and validated this method by comparing our results with those obtained from the standard method. Two line sources were imaged, the first a 70-cm long plastic tube filled with 6 MBq of F-18 (NEMA line source for clinical scanners) and the second a standard 20-cm long Ge-68 sealed line source (0.90 MBq). Point source data were sorted and analysed following the NEMA NU4-2008 method to calculate sensitivity profiles to be plotted as a function of axial distance relative to the center of the field of view. Line source data were analyzed in a manner analogous to the NEMA NU2-2001 method for calculating sensitivity for clinical PET systems. The results from the F-18 and Ge-68 are in good agreement with those from a Na-22 point source (0.93 MBq) using the NEMA standard methods. The difference in absolute sensitivity between Na-22 and the line sources are 0.90% for F-18 and 1.7% for Ge-68 line source. These results represent the equivalence of the sensitivity measurements using a line source or a point source.
Though an extensive amount of literature documents the improved learning gains made by interactive teaching compared to traditional lecture delivery, results vary widely between courses[1]. Part of the problem is that different instructors aim for active learning through widely varying (and sometimes conflicting) approaches[2]. In addition, even the most well-verified and effective teaching approach will fail without student buy in. I propose a simple framework that can help you identify effective active learning instructional strategies and how to implement them successfully. Results (both positive and less than positive) from a large first-year physics course will be discussed.
[1] one example among 100s: Freeman et al., Proceedings of the National Academy of Sciences 111, 8410 (2014). For a contrasting view, Andrews et al., CBE-Life Sciences Education 10, 394-405 (2011)
[2] Turpen and Finkelstein, Physical Review Special Topics-Physics Education Research 5, 020101 (2009)
This is a moderated panel discussion and Q&A (with NSERC reps, physicists and industry partners) on NSERC funding opportunities available to support researcher-industry partnerships. Learn how to get started, the challenges/rewards and tips for a successful partnership.
Panelists will be named as they are confirmed.
Over the past few decades, systematic research has shown that many physics students express essentially the same (incorrect) ideas both before and after instruction. It is frequently assumed that these ideas can be identified by research and then addressed through “interactive” teaching approaches such as hands-on activities and small-group collaborative work. In many classrooms, incorrect ideas are elicited, their inadequacy is exposed, and students are guided in reconciling their prior knowledge with the formal concepts of the discipline. Variations of this strategy have proven fruitful in science instruction at all levels from elementary through graduate school. However, this summary greatly over-simplifies the use of students’ ideas as the basis for effective instructional strategies. Examining what students have actually learned after using research-based curriculum is essential for improving the curriculum and validating its effectiveness.
In atomic physics, the many-body problem is computationally challenging. When theory is well understood, accurate calculations can predict results that may be difficult to measure experimentally. For heavy elements or highly ionized systems, relativistic and quantum electrodynamic effects, not to mention nuclear effects, are less well understood and computation can assess the limitation of theory when results are compared with those from experiment.
This talk will describe how an honours degree in mathematics and chemistry from the University of British Columbia led to research in computational atomic physics.
Chairholder Catherine Mavriplis will give an overview of the activities of the NSERC / Pratt & Whitney Canada Chair for Women in Science and Engineering for Ontario. As the Chair approaches the end of its term, we'll look back at the impact it has had in several areas including interdisciplinary research in Communications, Education, Sociology and History. Since the Chair program launch, over 5000 people have been engaged in direct programming through 75 events, over 70 Canadian companies have been contacted, 15 Ontario universities have coordinated outreach efforts, a strong online following has been developed (900 Twitter and over 100 LinkedIn followers, 1400 monthly web visitors), and the Chairholder has made 10 media appearances. Learn how you can get involved in this and other regional and national activities.
Antihydrogen is the simplest pure anti-atomic system and an excellent candidate to test the symmetry between matter and antimatter. In particular, a precise comparison of the spectrum of anytihydrogen with that of hydrogen would be an excellent test of Charge-Parity-Time symmetry. The ALPHA antihydrogen experiment is able to produce and confine antihydrogen atoms in an Ioffe-Pritchard type magnetic neutral atom trap. Once confined, resonant transitions (eg. positron spin resonance transitions, 1S - 2S transitions) in the anti-atoms can be excited. In order to determine the resonant frequencies, the magnetic field seen by the antihydrogen atoms must be measured. This presents a significant challenge because the nature of the ALPHA apparatus effectively eliminates the possibility to insert magnetic probes into the antihydrogen trapping volume. Furthermore, because of the highly inhomogeneous nature of the magnetic trapping fields, external probes will not be able to measure the relevant magnetic fields.
To solve this problem ALPHA developed an in situ magnetometry technique based on the cyclotron resonance of an electron plasma in a Penning trap. This technique can measure the local field seen by the antihydrogen atoms and therefore determine the resonant frequency of the desired transition. With this technique ALPHA was able to perform the first ever resonant interaction with antihydrogen atoms by exciting the positron spin flip transition. This talk will present our in situ magnetometry technique, the methods used to excite and identify positron spin flip transitions in antihydrogen, and future spectroscopic measurements being pursued by ALPHA.
Panelists: Svetlana Barkanova (Acadia University), Melanie Campbell (University of Waterloo), Charlotte Froese Fischer (NIST), Adriana Predoi-Cross (University of Lethbridge), and Michael Steinitz (St. Francis Xavier University).
Panelists: Svetlana Barkanova (Acadia University), Melanie Campbell (University of Waterloo), Charlotte Froese Fischer (NIST), Adriana Predoi-Cross (University of Lethbridge), and Michael Steinitz (St. Francis Xavier University).
C. Haley1, D. Degenstein2, R. Cooney3, and A. Bourassa2
1 Honeywell Aerospace
2 University of Saskatchewan
3 Canadian Space Agency
The Canadian Atmospheric Tomography System (CATS) is a UV/visible/near-IR spectrometer designed to measure limb-scattered sunlight to derive vertically-resolved concentrations of O3, NO2, and BrO and aerosol extinction from the Upper Troposphere through the Stratosphere. CATS is a follow-on to the Optical Spectrograph and Infrared Imager System (OSIRIS) instrument currently in operation on the Odin satellite. In addition to monitoring the stratosphere and extending the long time-series provided by OSIRIS, CATS will focus on the study of fine scale phenomena in the Upper Troposphere/Lower Stratosphere (UTLS) region. To accomplish this new goal, the current CATS design incorporates the following modifications over OSIRIS:
1) Increased spectral range, focussed on an improved aerosol product.
2) Better spectral resolution, aimed at improved NO2 and BrO data products.
3) Improved vertical resolution and sampling, important for measurements in the UTLS region.
4) Better horizontal (along-track) sampling, to allow a tomographic retrieval approach to be used.
The current status of the CATS instrument design and development will be reviewed, highlighting the changes from the OSIRIS instrument design, the main outstanding technical risks, and the current development activities. Mission implementation options on either a dedicated microsatellite or as a payload on a small satellite will also be presented.
Bio
Neil Rowlands obtained his B.Sc (Engineering Physics) from the University of Alberta in 1985 and his Ph.D. (Astronomy) from Cornell University in 1991. At Cornell, he participated in the construction and use of infrared instrumentation for the Kuiper Airborne Observatory and the 5m Hale telescope at Mt. Palomar. After post-doctoral fellowships at the Université de Montréal, and at the Canada Centre for Remote Sensing where he worked with infrared instrumentation, he joined CAL Corporation (Ottawa, ON), now Honeywell Aerospace, as an electro-optical engineer. Since 1995 he has been developing space-borne scientific instrumentation for the space physics, atmospheric sciences and astronomy communities. He is currently a Staff Scientist at Honeywell in Ottawa. He has been working on the Canadian contribution to the James Webb Space Telescope (JWST) project, the Fine Guidance Sensor (FGS/NIRISS), since 1997.
Lasing in the nitrogen molecular ion
Mathew Britton, Patrick Laferriere, Ladan Arissian, Michael Spanner and P. B. Corkum
Joint Attosecond Science Laboratory, National Research Council and University of Ottawa, Ottawa, Canada
Intense light-matter interaction beyond a unimolecular limit faces unique challenges. In this regime, light and matter both have a non-negligible effect on each other. It is in this complex environment that lasing has been discovered on a nitrogen molecular ion transition [1].
We investigate the gain dynamics in nitrogen ions created from a neutral gas by an intense ultrashort laser pulse. To isolate the phenomenon, we use a one atmosphere pure-nitrogen 200 µm thick gas jet in a vacuum chamber. The gain is initiated by an 800 nm pump pulse with intensity in the range of 2-4 x10^14 W/cm^2 and pulse duration of 27 fs. A weak second harmonic probe pulse monitors the time dependence of the gain on the B (v=0) to X (v=0) transition.
We observe a peak gain of approximately 2 over a distance of about 200 µm and we measure gain as a function of nitrogen concentration, density, and intensity of the pump and probe. While the gain is present immediately (i.e. within the duration of the 27 femtosecond pump pulse) we observe two time-scales of decay: population inversion decay and rotational wave packet decay.
[1] see for example, G. Point, Y. Liu, Y. Brelet, S. Mitryukovskiy, P. Ding, A. Houard, and A. Mysyrowicz, “Lasing of ambient air with microjoule pulse energy pumped by a multi-terawatt infrared femtosecond laser”, OPTICS LETTERS, 29, 1725, (2014)
Atomic frequency comb, an atomic ensemble with comb shaped optical transition, is useful for multimode photonic quantum memory where a photon is absorbed collectively over the teeth of the comb resulting in a multipartite entangled state. The teeth of the comb constitute the individual subsystems participating in the entanglement. Since each tooth of the comb consists of a macroscopic number of atoms (typically several thousand), the atomic frequency comb (AFC) system presents an entirely different class of entangled state, which we call the colossal entangled state, i.e., multipartite entanglement between macroscopic systems.
In this work we propose an experimentally realizable witness and entanglement measure for the colossal entanglement in the AFC systems which is the entanglement between the teeth of the AFC. The witness is achieved in two steps. First we determine the minimum number of teeth coherently absorbing the photon, i.e., the coherence depth, from the signal to noise ratio of the light coming out of the AFC system. We argue that coherence depth is synonymous to entanglement depth, i.e., the minimum number of provably entangled systems, for the case when exactly one photon is present in the system. However, higher photon number component in the photonic states can cause differences between the coherence depth and the entanglement depth. We rectify this problem by estimating the probabilities P0 of no photon and P1 of having exactly one photon in the AFC system and using the bound on P1 for a given P0 and entanglement depth derived in [Hass et al. 2014]. Our method requires no prior knowledge of the number of teeth and is scalable. Furthermore, the method uses only macroscopic quantities to estimate the entanglement in the system, hence, is a suitable choice for the experimental demonstration of genuine multipartite entanglement. We have numerical and experimental results to support our entanglement witness.
Attaining an isolated attosecond pulse via high harmonic generation requires a temporal gate that can act within one half cycle of the driving field. Here, we use the interplay of nonlinear optics and spatio-temporal coupling to synthesize a half-cycle pulse. The half cycle pulse is centered at 1.8 microns, the idler of an optical parametric amplifier, and is intense enough to generate isolated attosecond pulses, tuneable over an octave in the extreme ultraviolet. I will also discuss this tool to study attosecond dynamics in the condensed phase.
An experimental lifetime of exceptional accuracy [9.573(4)(5) (stat)(sys)] has been reported by Lapierre et al. [1] for the $2p$ $^2P_{3/2}$ state of Ar$^{13+}$. This result is in good agreement with theory [2] when neglecting the effect of the anomalous magnetic moment (AMM), namely 9.582(2) ms, whereas the lifetime with the AMM correction is 9.538(2) ms, well outside the experimental error bar.
The theory method used by Tupisyn et al. started with the non-relativistic operator for the line strength of the $2p$ $^2P_{1/2}$ - $^2P_{3/2}$ transition and applied relativistic perturbation theory to the calculation of the lifetime as the inverse of the transition probability between these two fine-structure levels.
The General Relativistic Atomic Structure Package (GRASP2K) [3] is different. It relies on a variational method for determining wave functions for the initial and final states and then a matrix element for a transition operator which, in the Gordon form, can determine the lifetime both with and without the AMM correction, using the observed transition energy. Our lifetimes, 9.5804(16) ms and 9.536(16) ms, respectively are in excellent agreement with the Tupystin et al. values. In GRASP2K calculations, a check on the accuracy of the wave function is the prediction of the transition energy and this is the basis for our error estimate. Thus the discrepancy with experiment for Ar$^{13+}$ remains unresolved.
Data will be presented for other ions of the isoelectronic sequence. For K$^{14+}$ a measured value [4] is closer to the value with the AMM correction but the uncertainty in the experimental lifetime is so large that it includes both values.
REFERENCES
[1] A. Lapierre et al., Phys, Rev. Letters, 95, 183001 (2005)
[2] I.I. Tupitsyn et al., Phys. Rev. A, 72, 062503 (2005)
[3] P. Jonsson et al., Comp. Phys. Commun., 184, 2197 (2013)
[4] E. Trabert et al., Phys. REv. A, **64"", 034501 (2001)
Conventional imaging systems are limited in their optical resolution by diffraction. Thus, super-resolution techniques are required to overcome this limit. Many super-resolution techniques, such as structured illumination (SIM) [1,2], have been developed. However, these techniques often take advantage of linear optical processes and only a few techniques applicable to nonlinear optical processes exist [3, 4]. Here, we propose a scheme similar traditional SIM compatible with coherent nonlinear processes such as second- and third-harmonic generation and predict a resolution improvement of up to ~4 fold.
In traditional SIM the resolution is doubled by capturing and utilizing spatial frequencies that would otherwise not be received by the imaging system [1]. This may be further enhanced if the saturable absorption of the fluorescent molecules can be utilized to collect even higher harmonics of the spatial frequencies [5]. Since coherent imaging systems are linear with respect to the electric field, the concepts of structured illumination may be generalized to nonlinear widefield microscopy modalities where field amplitudes instead of field intensities are measured [6]. We show that this is possible through the use of second-harmonic and third-harmonic widefield microscopy and show a resolution improvement of three- and four-fold, respectively. Our results suggest that a spatial resolution smaller than 100 nm may be achievable.
References:
We study field and radiation attributes of photonic nano-resonators composed of alternating metal and dielectric layers, known as hyperbolic metamaterials (HMMs). HMMs offer the ability to confine light in ultra-small volumes and enhance its interaction with matter, thereby increasing the spontaneous emission rates of nearby photon emitters through the Purcell effect. It has been suggested that one of the first applications of HMM nanophotonics is in the domain of single photon sources for use in quantum cryptography and quantum plasmonics. Here we describe the physics of HMM nano-resonators in terms of open cavity resonant modes known as quasinormal modes (QNMs). Using an analytical expansion of the photon Green function in terms of QNMs, we introduce a modelling technique that is orders of magnitude faster that direct dipole solutions of Maxwell's equations and offers considerable insight into the HMM coupling effects. We show how coupling to HMM nano-resonators can substantially increase spontaneous emission rates of quantum emitters by an order of magnitude more than pure metal resonators. However, in contrast to recent claims, we also show that most of this emission increase is lost to Ohmic heating. We demonstrate that, counter-intuitively, less metal present in the HMM resonator results in larger non-radiative losses. Using our semi-analytical QNM theory, we describe how this increase in photon quenching originates from an increased overlap between the metal and dielectric, which allows fields to leak or tunnel into the lossy metallic regions. We thus conclude that HMM nano-resonators likely make poor single photon sources, and that pure metallic resonators are preferred for single photon applications.
Vortex beams form a class of beams carrying orbital angular momentum (OAM). A single photon carries lħ OAM where l represents the OAM state and a beam with non-zero OAM state has a zero intensity at its centre and a helical phase wavefront.
Vortex beams have gained interest for their applications in optical manipulation, optical communication and quantum information [1-3]. In particular, they can enhance communication security by improving the quantum key distribution (QKD) procedure [4]. The original proposal uses the photon polarization degree of freedom, resulting in each photon carrying a single bit. Since OAM states are unbounded and mutually orthogonal, using instead the OAM degree of freedom as a basis enables far greater channel capacity. As QKD requires superpositions of states, this improved version of QKD requires superpositions of different OAM values.
There are many ways to generate vortex beams with bulk optics, such as spiral phase plates, spatial light modulators, q-plates and cylindrical lens mode converters [5-8]. However, an integrated photonic approach has advantages over bulk optics because of its scalability, stability and small size. It turns out that ring resonators with lateral grating elements, called angular gratings, radiates a vortex above the structure when on resonance [9,10]. To generate a superposition of vortex beams, we expand this idea to a single ring with two sets of gratings, one on the inside wall and one on the outside. We then show with simulations that, after post-selecting on one of the circular polarizations, we can generate OAM superposition states based on the number of grating elements for each grating.