Experimental Atomic Physics

Isaac Abella

Ph.D., Columbia, 1963.
Professor, Dept. of Physics and the College.
Experimental atomic physics, quantum optics, laser spectroscopy.

Laser Coherent Transients. Photon echo techniques are used to probe metastable excited states in rare gas mixtures such as helium, neon, and argon. The states are produced in a weakly ionized r.f. plasma discharge, and nitrogen-pumped dye lasers are used to generate the coherent super-position states.

Spectroscopy of Rare-Earth Laser Material. Samples of YLF and YAG crystals doped with erbium, thulium, and holmium are being studied with selective laser excitation in the region of 780 nm, the erbium bands. These materials can be efficiently optically pumped by the AlGaAs-GaAs laser diode arrays, but we are using dye laser excitation. We are interested in the energy transfer process: Er to Tm, to Ho, which concentrates energy emission at 2.085 microns at room temperature and at liquid nitrogen. The process is a radiationless, almost resonant transfer of energy between sites and depends on the relative concentrations of the rare earth ions. In particular we are interested in measuring decay rates, excited state absorption, and branching ratios and detailed theories of such processes.

Selected Publications:

  • Upconversion Coefficient Measurements in Tm3+, Ho3+: YAG at Room Temperature. G. Kintz, I. D. Abella and L. Esterowitz. In Proceedings of International Conference on Lasers 87. Ed. F. J. Duarte, STS Press, McLean VA, 1988, p.398.
  • Differences in Decay Kinetics and Mechanisms of Cr3+ -> Tm3+ Energy Transfer in YSGG and YAG. G. Quarles, A. Rosenbaum, I. D. Abella, C.L. Marquardt and L. Esterowitz. In LEOS Conference 89: Proceedings. IEEE Publ. 89-CH2641-9, 1989, p.235.
  • Efficient room-temperature operation of Cr3+-sensitized, flashlamp-pumped 2 micrometer lasers. G. Quarles, A. Rosenbaum, I.D. Abella, C.L. Marquardt, and L. Esterowitz. Opt. and Quantum Electronics, 22, S141, 1990.
  • Lasers and Application. I.D. Abella. In Physics for Scientists and Engineers (with Modern Physics), R.A. Serway, Saunders College Publishing, Philadelphia, 1990, p.1246.
  • National Science Education Standards. Report of National Research Council, National Academy of Sciences. I.D. Abella, member of Science Content Standards, National Academy Press, Washington DC, 1996.
  • (Articles) Radio Waves. Radar. I. D. Abella. In Macmillan Encylopedia of Physics, Macmillan Press, New York, 1996.

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Updated 3/98 or later

Cheng ChinCheng Chin

Ph.D., Stanford University, 2001.
Assistant Professor, Department of Physics and James Franck Institute.
Laser cooling and trapping, degenerage quantum gases.
Cheng Chin's homepage

Bose-Einstein condensation of molecules and Fermionic superfluids. The formation and condensation of composite bosons by pairing fermionic atoms open the door to the exploration of superfluidity in different regimes. In the strong-coupling limit, atoms form short-ranged molecules, which undergo Bose-Einstein condensation (BEC) at low temperatures. In the weak-coupling regime, Cooper-pairing of atoms occurs in the Bardeen-Cooper-Schrieffer (BCS) state. In the crossover regime, the two types of superfluid smoothly connect to a new type of resonance superfluid, for which a universal behaviour is predicted.

Scalable quantum manipulation and quantum computation. Computation in the realm of quantum mechanics can be exponentially faster than its classical counterpart. In spite of the abundance of proposals to implement quantum computation, few systems have been experimentally demonstrated or can in principle be scalable to many quantum bits (qubits).

Ultracold atoms in an optical lattice formed by optical standing waves are a promising system to realize a scalable quantum computation system. By tuning the relative phase of the standing waves, arbitrary two atoms can be entangled by bringing them into close spatial vicinity. Repeating the above entanglement process on different atom pairs, we can establish quantum entanglement of many atoms. Since atoms can be individually trapped in the lattice with a typical periodicity of the optical wavelength, many qubits can be stored within a small volume of several cubic microns.

Selected Publications:

  • Observation of the Pairing Gap in a Strongly Interacting Fermi Gas. C. Chin, M. Bartenstein, A. Altmeyer, S. Riedl, S. Jochim, J. Hecker Denschlag, and R. Grimm, Science, Vol. 305, 1128 (2004).
  • Bose-Einstein Condensation of Molecules. S. Jochim, M. Bartenstein, A. Altmeyer, G. Hendl, S. Riedl, C. Chin, J. Hecker Denschlag and R. Grimm. Science, Vol. 302, 2101 (2003).
  • Preparation of a Pure Molecular Quantum Gas. J. Herbig, T. Kraemer, M. Mark, T. Weber, C. Chin, H.-C. Nägerl and R. Grimm. Science, Vol. 301, 1510-1513 (2003).

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Updated 01/2005

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Zheng-Tian LuZheng-Tian Lu

Ph.D., University of California at Berkeley, 1994.
Senior Physicist, Physics Division, Argonne National Laboratory. Professor (part time), Department of Physics and Enrico Fermi Institute.
Experimental physics, atomic physics.
Zheng-Tian Lu's homepage

Testing time-reversal symmetry in atoms and nuclei. We are searching for a permanent electric-dipole moment (EDM) of the 225Ra atom (t1/2 = 15 d). A positive finding would signify the violation of time-reversal symmetry. This experiment provides an outstanding opportunity to search for new physics beyond the Standard Model. We have succeeded in realizing laser trapping and cooling of radium atoms (both 226Ra and 225Ra). At present, we are developing the techniques and apparatus needed for the EDM measurements with cold 225Ra atoms. See AIP News 812-3 (2007).

Radio-krypton dating. The Atom Trap Trace Analysis (ATTA) method has revolutionized our ability to measure radiokrypton isotopes, 81Kr (t1/2 = 229,000 yr) and 85Kr (t1/2 = 10.8 yr), in samples of natural material. This in turn opens the door to a wide range of new applications in the Earth sciences. 81Kr measurements of groundwater samples from the Nubian Aquifer in the Western Desert of Egypt showed residence times approaching one million years. At present, we are developing the next generation instrument, ATTA-3, which is expected to further reduce sample sizes required for radiokrypton analyses of groundwater and glacial ice. See AIP News 679-3 (2004).

Studying exotic nuclear structure. Helium-8 (8He) is the most neutron-rich matter that can be synthesized on earth: it consists of two protons and six neutrons, and remains stable for an average of 0.2 seconds. Because of its intriguing properties, 8He has the potential to reveal new aspects of the fundamental forces among the constituent nucleons. We have recently succeeded in laser trapping and cooling this exotic helium isotope and have performed precision laser spectroscopy on individual trapped atoms. Based on atomic frequency differences measured along the isotope chain 3He-4He-6He-8He, the nuclear charge radius of 8He has been determined for the first time. The result can now be compared with the values predicted by a number of nuclear structure calculations and is testing their ability to characterize this loosely-bound halo nucleus. See AIP News 851-2 (2007).

Selected Publications:

  • Nuclear charge radius of He-8. P. Mueller et al., Phys. Rev. Lett. 99, 252501 (2007).
  • Laser-trapping of Ra-225 and Ra-226 with repumping by room-temperature blackbody radiation. J. R. Guest et al. Phys. Rev. Lett. 98, 093001 (2007).
  • Laser spectroscopic determination of the 6He nuclear charge radius. L.-B. Wang et al. Phys. Rev. Lett., 93, 142501 (2004).
  • Tracing Noble Gas Radionuclides in the Environment. P. Collon, W. Kutschera and Z.-T. Lu., Ann. Rev. Nucl. Part. Sci., Vol. 54, 39 (2004). Nucl-ex/0402013.
  • Search for anomalously heavy isotopes of helium in the Earth’s atmosphere. P. Mueller et al. Phys. Rev. Lett. 92, 022501 (2004).

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Updated 1/2008

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