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Research projects

Atomic gravimetry

This project uses a magneto-optical trap to study the gravitational force. Here we develop techniques to improve the atomic interferometry aimed to measure small forces, especially of the gravitational kind. As part of this research line we participate in the Gravico collaboration for the development of portable gravimeters.

Publications
-A. López Vázquez, Y.M. Torres, M.S. Billión, W.M. Pimenta, J.A. Franco-Villafañe and E. Gomez, “Experimental generation of a flat-top beam profile in a stable ring cavity,” Opt. Lett. 44, 4428 (2019).
-N. Arias, L.J. González, V. Abediyeh and E. Gomez, “Frequency locking of multiple lasers to an optical cavity,” J. Opt. Soc. Am. B 35 (10), 2394 (2018).
-N. Arias, V. Abediyeh, S. Hamzeloui and E. Gomez, "Low phase noise beams for Raman transitions with a phase modulator and a highly birefringent crystal," Opt. Exp. 25 (5), 5290 (2017).
-S. Hamzeloui, D. Martínez, V. Abediyeh, N. Arias, E. Gomez and V. M. Valenzuela, "Dual atomic interferometer with a tunable point of minimum magnetic sensitivity," Phys. Rev. A 94, 033634 (2016).
-S. Hamzeloui, N. Arias, V. Abediyeh, D. Martínez, M. Gutiérrez, E. Uruñuela, E. del Rio, E. Cerda-Méndez, E. Gomez, "Towards Precision Measurements at UASLP," J. Phys. 698, 012011 (2016).
-T. Matos y E. Gomez, "Space-Time Curvature Signatures in Bose-Einstein Condensates," Eur. Phys. J. D. 69, 125 (2015).
-L.O. Castaños, E. Gomez, "Model for a phase-space selector using microwave transitions," Phys. Rev. A 89, 013406 (2014).
-V.M. Valenzuela, S. Hamzeloui, M. Gutiérrez, E. Gomez, “Multiple isotope magneto-optical trap from a single diode laser,” J. Opt. Soc. Am. B 30, 1205 (2013).
-V.M. Valenzuela, L. Hernández, E. Gomez, “High power rapidly tunable system for laser cooling,” Rev. Sci. Instrum. 83, 015111 (2012).
-S. Martínez, L. Hernández, D. Reyes, E. Gomez, M. Ivory, C. Davison, S. Aubin, “Fast, small and low vibration mechanical laser shutters,” Rev. Sci. Instrum. 82, 046102 (2011).


Francium spectroscopy for the study of the weak force

This project is part of the FrPNC project at TRIUMF in Vancouver, Canada, directed by Luis Orozco (Joint Quantum Institute) and Gerald Gwinner (University of Manitoba). Francium is the heaviest of the alkali atoms so it has both a big nucleus and a relatively simple atomic structure. The big nucleus amplifies the effects of the weak force and we use the very sensitive tools of atomic spectroscopy to measure these small effects. We are interested in particular in studying neutral weak currents between nucleons inside the nucleus. The main effect of such interaction is to introduce a parity violating moment called the anapole moment. We observe this violation by detecting a hyperfine transition that is only allowed due to the anapole moment. These measurements will increase our understanding of the weak force inside the nucleus. This project evolved from the work on francium done by the group of Luis Orozco, where we manage to capture large quantities of francium in a magneto-optical trap and studied its atomic structure. See the press release about our recent commissioning run. For general information about the project see:

-E. Gomez, S. Aubin, G. D. Sprouse, L. A. Orozco, D. P. DeMille, “Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms,” Phys. Rev. A 75, 033418 (2007)
-E. Gomez, L. A. Orozco, G. D. Sprouse, “Spectroscopy with trapped francium; advances and perspectives for weak interaction studies,” Rep. Prog. Phys. 69, 79 (2006).

Other members of the collaboration: Prof. G. Gwinner (University of Manitoba), Prof. L.A. Orozco (Joint Quantum Institute), Prof. G.D. Sprouse (Stony Brook University), Dr. J.A. Behr (TRIUMF), Dr. K.P. Jackson (TRIUMF), Dr. M.R. Pearson (TRIUMF), Prof. V.V. Flambaum (University of New South Wales), Prof. S.A.M. Aubin (College of William and Mary)

Additional publications
-M. R. Kalita, J. A. Behr, A. Gorelov, M. R. Pearson, A. C. DeHart, G. Gwinner, M. J. Kossin, L. A. Orozco, S. Aubin, E. Gomez, M. S. Safronova, V. A. Dzuba and V. V. Flambaum, “Isotope shifts in the 7s - 8s transition of francium: Measurements and comparison to ab initio theory,” Phys. Rev. A 97, 042507 (2018).
-R. Collister, J. Zhang, M. Tandecki, S. Aubin, E. Gomez, G. Gwinner, L.A. Orozco, M.R. Pearson and J.A. Behr, “Photoionization of the francium 7P3/2 state,” Can. J. Phys. 95, 234 (2017).
-J. Zhang, R. Collister, K. Shiells, M. Tandecki, S. Aubin, J. A. Behr, E. Gomez, A. Gorelov, G. Gwinner, L. A. Orozco, M. R. Pearson and Y. Zhao, "Efficient inter-trap transfer of cold francium atoms," Hyp. Inter. 237, 150 (2016).
-J. Zhang, M. Tandecki, R. Collister, S. Aubin, J. A. Behr, E. Gomez, G. Gwinner, L. A. Orozco, M. R. Pearson and G. D. Sprouse, "Hyperfine Anomalies in Fr: Boundaries of the Spherical Single Particle Model," Phys. Rev. Lett. 115, 042501 (2015).
-M. Tandecki, J. Zhang, S. Aubin, J.A. Behr, R. Collister, E. Gomez, G. Gwinner, H. Heggen, J. Lassen, L.A. Orozco, M.R. Pearson, S. Reader y A. Teigelhöfer, "Offline trapping of 221Fr in a magneto-optical trap from implantation of an 225Ac ion beam," J. Instr. doi:10.1088/1748-0221/9/10/P10013 (2014).
-R. Collister, G. Gwinner, M. Tandecki, J.A. Behr, M.R. Pearson, J. Zhang, L. Orozco, S. Aubin y E. Gomez, "Isotope shifts in francium isotopes 206-213Fr and 221Fr," Phys. Rev. A 90, 052502 (2014).
-M. Tandecki, J. Zhang, R. Collister, S. Aubin, J.A. Behr, E. Gomez, G. Gwinner, L.A. Orozco y M.R. Pearson, “Commissioning of the Francium Trapping Facility at TRIUMF,” J. Inst. doi:10.1088/1748-0221/8/12/P12006 (2013).
-S. Aubin, J.A. Behr, G. Chen, R. Collister, V.V. Flambaum, E. Gomez, G. Gwinner, K.P. Jackson, D. Melconian, L.A. Orozco, M.R. Pearson, M.C. Ruiz, D. Sheng, Y.H. Shin, G.D. Sprouse, M. Tandecki, J. Zhang y Y. Zhao, “The Francium Facility At TRIUMF,” AIP Conf. Proc. 1525, 530 (2013).
-S. Aubin, J.A. Behr, R. Collister, V.V. Flambaum, E. Gomez, G. Gwinner, K.P. Jackson, D. Melconian, L.A. Orozco, M.R. Pearson, D. Sheng, G.D. Sprouse, M. Tandecki, J. Zhang and Y. Zhao, "Atomic parity non-conservation: the francium anapole project of the FrPNC collaboration at TRIUMF," Hyp. Inter. 214, 163 (2013).
-S. Aubin, E. Gomez, J.A. Behr, M.R. Pearson, D. Sheng, J. Zhang, R. Collister, D. Melconian, V.V. Flambaum, G.D. Sprouse, L.A. Orozco and G. Gwinner, "The FrPNC Experiment at TRIUMF: Atomic Parity Non-Conservation in Francium," AIP Conf. Proc. 1441, 555 (2012).
-S. Aubin, E. Gomez, J.A. Behr, M.R. Pearson, D. Sheng, J. Zhang, R. Collister, D. Melconian, Y. Zhao, V.V. Flambaum, G.D. Sprouse, L.A. Orozco and G. Gwinner, "Atomic parity non-conservation in francium: The FrPNC experiment at TRIUMF," Il Nuovo Cimento 35(4), 85 PAVI (2011).
-E. Gomez, S. Aubin, R. Collister, J.A. Behr, G. Gwinner, L.A. Orozco, M.R. Pearson, M. Tandecki, D. Sheng and J. Zhang, "The FrPNC Experiment, weak interaction studies in Francium at TRIUMF," J. Phys. 387, 012004 (2012).
-D. Sheng, L.A. Orozco, E. Gomez, “Preliminary studies for anapole moment measurements in rubidium and francium,” J. Phys. B 43, 074004 (2010).
-E. Gomez, S. Aubin, L.A. Orozco, G.D. Sprouse, E. Iskrenova-Tchoukova, M.S. Safronova, “Nuclear magnetic moment of 210Fr: A combined theoretical and experimental approach,” Phys. Rev. Lett. 100, 172502 (2008).
-A.P. Galvan, Y. Zhao, L.A. Orozco, E. Gomez, A.D. Lange, F. Baumer, G.D. Sprouse, “Comparison of hyperfine anomalies in the 5S1/2 and 6S1/2 levels of 85Rb and 87Rb,” Phys. Lett. B 655, 114 (2007).
-G. Gwinner, E. Gomez, L.A. Orozco, A.P. Galvan, D. Sheng, Y. Zhao, G.D. Sprouse, J.A. Behr, K.P. Jackson M.R. Pearson, S. Aubin, V.V. Flambaum, “Fundamental symmetries studies with cold trapped francium atoms at ISAC,” Hyperfine Interactions 172, 45 (2006).
-E. Gomez, F. Baumer, A. D. Lange, G. D. Sprouse , “Lifetime Measurement of the 6s Level of Rb,” Phys. Rev. A 72, 012502 (2005).
-E. Gomez, L. A. Orozco, A. Perez Galvan, and G. D. Sprouse, “Lifetime Measurement of the 8s Level in Francium,” Phys. Rev. A 71, 062504 (2005).
-E. Gomez, S. Aubin, L. A. Orozco, and G. D. Sprouse, “Lifetime and hyperfine splitting measurements on the 7s and 6p levels in rubidium,” J. Opt. Soc. Am. B 21, 2058 (2004).
-S. Aubin, E. Gomez, L. A. Orozco, and G. D. Sprouse, “Lifetimes of the 9s and 8p levels of atomic francium,” Phys. Rev. A 70, 042504 (2004).
-S. Aubin, E. Gomez, K. Gulyuz, L. A. Orozco, J. Sell, G. D. Sprouse, “Francium developments at Stony Brook,” Nucl. Phys. A 746, 459C (2004).
-S. Aubin, E. Gomez, L. A. Orozco, and G. D. Sprouse, "Lifetime measurement of the 9s level of atomic francium," Opt. Lett. 28, 2055 (2003).
-S. Aubin, E. Gomez, L. A. Orozco, and G. D. Sprouse, "High efficiency magneto-optical trap for unstable isotopes," Rev. Sci. Instr. 74, 4342 (2003).
-G. D. Sprouse, S. Aubin, E. Gomez, J. M. Grossman, L. A. Orozco, M. R. Pearson, and M. True, "Atomic probes of electromagnetic and weak interactions with trapped radioactive atoms, " Eur. Phys. J. A. 13, 239 (2002).
-S. Aubin, E. Gomez, J. M. Grossman, L. A. Orozco, M. R. Pearson, G. D. Sprouse, and D. P. Demille, "Francium spectroscopy and a possible measurement of the nuclear anapole moment," Proceedings of the XV International Conference on Laser Spectroscopy, Edited by S. Chu, V. Vuletic, A. J. Kemand and C. Chin, World Scientific, Singapore (2002) p. 305.


Single molecule FRET

The project exploits the technique of FRET (Forster Resonance Energy Transfer) at the level of single molecules. The excitation in one fluorophore gets transferred to a second fluorophore near by. The transfer efficiency depends on the distance and therefore this method is useful to measure very small distances. The measurement of the excitation for a single molecule requires sensitive detection at the level of individual photons. We are applying the technique to study biological systems. The project is in collaboration with Prof. Jaime Ruiz (IF UASLP), and Prof. Alfredo Mendez (IF UASLP).

We have demonstrated that the ends of the RNA molecule are in close (and fairly constant) proximity independent on the RNA length
- N. Leija-Martínez, S. Casas-Flores, R.D. Cadena-Nava, J.A. Roca, J.A. Mendez-Cabañas, E. Gomez y J. Ruiz-Garcia, "The separation between the 5'-3' ands in long RNA molecules is short and nearly constant," Nucleic Acid Research 42, 13963 (2014).


Optical tweezers

The project uses laser beams to manipulate objects with an optical tweeezers. A micron sized sphere is trapped at the focus of a laser beam. The small sphere works as a lens and any small motion of the sphere causes deflection of the laser beam. We detect the deflection to measure small displacements and forces. We are applying the technique to study biological systems. The project is in collaboration with Prof. Jaime Ruiz (IF UASLP), and Prof. Alfredo Mendez (IF UASLP).