Home page of Stephen Choi

My main research area is in the theoretical study of Ultracold atoms, particularly Bose-Einstein condensates (2001 Nobel Lectures). This builds on the now-ubiquitous atom cooling and trapping work (1997 Nobel Lectures), and is closely related to the study of superconductors and superfluids (2003 Nobel Lectures). In addition to the Many-body and Condensed Mattter Physics aspect, this research is closely aligned with the techniques of Quantum Optics (2005 Nobel Lectures). The goal now is to explore possible applications of ultracold atoms such as in Quantum Information Processing and Quantum Simulations. I am also interested in Quantum Nonlinear Dynamics and Chaos as a general mathematical formalism for interdisciplinary research.

Personal Data

Senior Postdoctoral Researcher, University of Massachusetts, Boston, U.S.A. (Nov. 2006 - Present)

Postdoctoral Research Fellow, University of Rochester, U.S.A. (Nov. 2001 - Oct. 2006)

Royal Commission Research Fellow, University of Oxford, United Kingdom (Oct. 1999 - Oct. 2001)

Ph. D., University of Oxford, United Kingdom (March 2000)
          Domus Senior Scholar, Merton College, University of Oxford

B. Sc., M. Sc. (First Class Honours), University of Auckland, New Zealand (May 1994, May 1996)

Research Projects

Bose-Einstein Condensation (BEC)

BEC is a unique soft condensed matter system with a vast number of aspects to be studied. So far, I have studied some of the more fundamental issues relating to BEC. Some of these include the study of the damping of quasiparticle excitations, time-dependent dynamics based on Hartree-Fock-Bogoliubov theory, determination of the quantum many-body wave function, analogies with the quantum Hall effect, and the quantum entanglement resulting from intrinsic interatomic interactions.

Superfluidity; Vortex Matter

One of the most fruitful areas of study in Physics is the study of superfluidity. BEC is a novel superfluid system which exhibits many of the properties which can not be easily tested and confirmed in Helium-4. In particular, I have studied dynamical formation of vortices and the detailed structure of the elementary excitations of vortex lattices including the Tkachenko, hydrodynamic bulk, and surface modes.

Atom Lasers; Quantum Control

BEC may also be viewed as a highly intense source of coherent atoms with a well-defined phase, just as a laser is a source of coherent, high-intensity photons. In this context, I have studied rudimentary BEC atom optics, output coupling of BEC from its confining trap potential, spatio-temporal interferometry "quantum carpet" of BEC, quantum nondemolition measurement using BEC, and various methods to quantum control a BEC.

MIT-Harvard Center for Ultracold Atoms

JILA/NIST BEC Homepage

APS Research Journals

arXiv Preprint Server

Rochester Cooling and Trapping Group

Oxford BEC Theory Group

Publications in Refereed Journals

'Coherence of bichromatic beam splitter for two-level atoms', S. Choi, H.M. Wiseman, S.M. Tan, and D.F. Walls. Phys. Rev. A, 55 527 (1997)

'Atom optical elements for Bose-Enstein condensates', S. Choi and K. Burnett. Phys. Rev. A, 56 3825 (1997)   arXiv

'Comparison between bichromatic beams splitters for two- and three- level atoms', M.K. Olsen, S.Choi, H.M. Wiseman, S.M. Tan, and D.F. Walls. Opt. Comm. 147 382 (1998)

'Non-linear mixing of quasiparticles in inhomogeneous Bose condensate' S. A. Morgan, S. Choi, K. Burnett, and M. Edwards Phys. Rev. A 57 3818 (1998)

'Phenomenological damping in trapped atomic Bose-Einstein condensate' S. Choi, S. A. Morgan, and K. Burnett Phys. Rev. A 57 4057 (1998)   arXiv

'Comparing alternative mean-field theories for trapped Bose gas' N. P. Proukakis, S. A. Morgan, S. Choi, and K. Burnett   Phys. Rev. A 58 2435 (1998)

'Exciting, cooling and vortex trapping in trapped atomic Bose-Einstein condensates' R. J. Marshall, G. H. C. New, K. Burnett, and  S. Choi Phys. Rev. A 59 2085 (1999)  arXiv

'Coherent output, stimulated quantum evapouration and pair breaking in a trapped atomic Bose gas' Y. Japha, S. Choi, K. Burnett, and Y. B. Band Phys. Rev. Lett. 82 1079 (1999)

'Adiabatic output coupling of a Bose gas at finite temperatures' S. Choi, Y. Japha, and K. Burnett   Phys. Rev. A 61 063606 (2000)

'Spatiotemporal interferometry with trapped atomic Bose-Einstein Condensates' S. Choi, K. Burnett, O. M. Friesch, B. Kneer, W. P. Schleich Phys. Rev. A 63 065601 (2001)   arXiv

'Squeezing and temperature measurement in trapped, atomic Bose-Einstein condensates' J. Rogel-Salazar, G. H. C. New, S.Choi, and K. Burnett J. Phys. B 34 4617 (2001)   arXiv

'Interactions and entanglements in BEC' K. Burnett, S. Choi, M. Davis, J. Dunningham, S. Morgan, and M. Rusch C. R. Acad. Sci. Series IV 2 399 (2001)

'Atom lasers using trapped atomic Bose-Einstein condensated' S. Choi Recent Research Developments in Physics 3 47 Eds. M. Kawasaki, N. Ashgriz, R. Anthony (2002)

'Quantum nondemolition measurements using Bose-Einstein condensates' S. Choi and K. Burnett J. Phys. B 35 L43 (2002)   arXiv

'Squeezing and entanglement in quasiparticle excitations of Bose-Einstein condensates' J. Rogel-Salazar, G. H. C. New, S. Choi and K. Burnett Phys. Rev. A 65 023601 (2002)   arXiv

'Geometric phases of macroscopic spin in Bose-Einstein Condensates' I. Fuentes-Guridi, J. Pachos, S. Bose, V. Vedral, and S. Choi Phys. Rev. A 66 022102   (2002)   arXiv;   Featured in Virtual Journal of Nanoscale Science and Technology

'Characterisation of the dynamical quantum state of a zero temperature Bose-Einstein Condensates' J. Rogel-Salazar, S. Choi, G. H. C. New, and K. Burnett Phys. Lett. A 299 476 (2002)   arXiv

'Mechanical response functions of finite temperature Bose-Einstein Condensates. S. Choi, V. Chernyak, and S. Mukamel Phys. Rev. A 67 043602 (2003)   arXiv

'Generalized coherent state representation of Bose-Einstein condensates' V. Chernyak, S. Choi, and S. Mukamel Phys. Rev. A 67 053604 (2003)   arXiv

'Excitation spectrum of vortex lattices in rotating Bose-Einstein condensates' S. Choi, L. O. Baksmaty, S. J. Woo, and N. P. Bigelow Phys. Rev. A 68 031605(R) (2003)   arXiv

'Tkachenko waves in rapidly rotating Bose-Einstein condensates' L. O. Baksmaty, S. J. Woo, S. Choi, and N. P. Bigelow Phys. Rev. Lett. 92 160405 (2004)   arXiv

'Excitation spectroscopy of vortex lattices in a rotating Bose-Einstein condensates' S. J. Woo, L. O. Baksmaty, S. Choi, and N. P. Bigelow Phys. Rev. Lett. 92 170402 (2004)   arXiv

'Methods of quantum field theory for trapped Bose-Einstein condensates' J. Rogel-Salazar, S. Choi, G. H. C. New, and K. Burnett J. Opt. B:Quant. Semiclass. Opt. 6 R33 (2004)

'Nonlinear response functions of strongly correlated boson fields: Bose-Einstein condensates and Fractional Quantum Hall systems' S. Choi, O. Berman, V. Chernyak, and S. Mukamel Las. Phys. 14 1342 (2004)   arXiv

'Quantum control via Feshbach resonance in Bose-Einstein condensates' S. Choi and N. P. Bigelow J. Mod. Opt. 52 1081 (2005)   arXiv

'Controlling quasiparticle excitations in a trapped Bose-Einstein condensate' S. J. Woo, S. Choi, and N. P. Bigelow Phys. Rev. A 72 021605(R) (2005)   arXiv

'Quantum squeezing and entanglement in a two-mode Bose-Einstein condensate with time-dependent Josephson-like coupling' S. Choi and N. P. Bigelow Phys. Rev. A 72 033612 (2005)   arXiv

'Initial steps towards quantum control of atomic Bose-Einstein condensates' S. Choi and N. P. Bigelow J. Opt. B: Quant. Semiclass. Opt. 7 S413 (2005)

'Chiral edge states of vortex matter' L. O. Baksmaty, S. J. Woo, M. Banks, S. Choi, and N. P. Bigelow Phys. Rev. A 72 063615 (2005)

'Vortex matter in atomic Bose-Einstein condensates' S. Choi, L. O. Baksmaty, S. J. Woo and N. P. Bigelow Trends in Boson Research,   A. V. Ling, Ed., Nova Science Publishers, New York (2006)

'Dynamics of vortex matter in rotating two species Bose-Einstein condensates' S. J. Woo, S. Choi, L. O. Baksmaty, and N. P. Bigelow Phys. Rev. A 75 031604(R) (2007)   arXiv

'An Atom Laser is not monochromatic' S. Choi, D. Stromberg, and B. Sundaram Phys. Rev. A 77 043620 (2008)   arXiv;   Featured in APS Physics News Update and Virtual Journal of Quantum Information

'Bose-Einstein condensates as a nonlinear Ramsey interferometer operating beyond the Heisenberg Limit' S. Choi, and B. Sundaram Phys. Rev. A 77 053613 (2008)   arXiv;   Featured in Virtual Journal of Quantum Information

'A quantum description of bubble growth in a superheated fluid' S. Choi, K. M. Galdamez, and B. Sundaram Phys. Lett. A 374 3280 (2010)   arXiv

'Quantum-Classical transition in a Stroboscopically measured system' S. Choi, K. Jacobs, and B. Sundaram Submitted for publication

'Semiclassical dynamics of atomic Bose-Einstein condensates' S. Choi, and B. Sundaram Submitted for publication   arXiv

'Single photon cooling in a wedge billiard' S. Choi, B. Sundaram, and M. G. Raizen Submitted for publication