Sajeev John
Theoretical Condensed Matter Physics and Quantum Optics
Professor: Ph.D., Harvard (1984); Assistant Professor, Princeton
(1986-89); S.B. M.I.T., (1979); NSERC Postdoctoral Fellow, University
of Pennsylvania (1984-86); Consultant, Exxon Research
(1985-89); Consultant, Bell Communication Research (1989); Principal
Investigator, Photonics Research
Ontario; Herzberg Medal (1995), McLean Senior Fellow (1996), Steacie
Prize (1997), Killam Fellowship (1998-2000).
Condensed matter physics, disordered systems, optical properties,
localization, many-body theory, magnetism, superconductivity.
Phone: (416) 978-3459 Fax: (416) 978-2537
e-mail:
john@physics.utoronto.ca
Research Interests
It has recently been demonstrated experimentally that in a new class of
dielectrics light can exhibit localization. We are studying the implications
of localization in quantum-electrodynamics. This involves new phenomena
such as photon-atom bound states as well as the reexamination of nonlinear
optics, cooperative behaviour of atoms, laser activity and photo-chemistry
in this context. These dielectric materials are the photonic analogs of
semi-conductors and may have important technological applications.
High Tc transition metal oxides constitute a major new frontier
in solid state theory in which electron-electron interactions are not small
compared to band effects. Novel
collective effects in the electron spin field interact strongly
with the electronic charge giving rise to what is known as a quantum spin
liquid phase. We are investigating the nature of this new magnetic phase
and possible origins of superconductive pairing.
In disordered media, multiple scattering of light leads to complication
for spectroscopic studies. Recently, we have developed a theory that enables
the reconstruction of the dynamic structure factor of the medium from a
light scattering experiment. A major application is the use of photon
diffusion as a diagnostic tool for metabolic imaging in medicine. We
are currently trying to refine this spectroscopic tool to detect tumors
in biological tissue. Another important application is in the understanding
of the newly discovered ''Laser
Paints''
Current Members of the Research Group
Ph.D. Students
|
Research Associates and PDF's
|
Visiting Professor
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* McLean Junior Fellow
Selected Publications
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"Electromagnetic Absorption in a Disordered Medium near a Photon Mobility
Edge", Sajeev John, Phys. Rev. Lett. 53, 2169 (1984).
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"Spin Glass State of a Randomly diluted Granular Superconductor", Sajeev
John and T.C. Lubensky, Phys. Rev. Lett. 55, 1014 (1985).
ABSTRACTPDF
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"Theory of the Electron Band Tails and the Urbach Optical Absorption Edge",
Sajeev John, C. Soukoulis, Morrel H. Cohen and E.N. Economou, Phys.
Rev. Lett. 57, 1777 (1986). ABSTRACTPDF
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"Strong Localization of Photons in Certain Disordered Dielectric Superlattices",
Sajeev John, Phys. Rev. Lett. 58, 2486 (1987). ABSTRACTPDF
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"Localization and the Density of States for an Electron in a Quantized
Elastic Continuum", Sajeev John, Physical Review B 35, 9291
(1987). ABSTRACTPDF
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"Density of States for an Electron in a Correlated Gaussian Random Potential:
Theory of the Urbach Tail", Sajeev John, M.Y. Chou, M.H. Cohen and C.M.
Soukoulis, Phys. Rev. B 37, 6963 (1988). ABSTRACTPDF
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"Temperature Dependence of the Urbach Edge: A Theory of Multiple Phonon
Absorption and Emission Sidebands", C. Grein and Sajeev John, Phys.
Rev. B 39, 1140 (1989). ABSTRACTPDF
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''Localization of Light'', S. John,
Physics
Today, May (1991), Cover Story.
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''Quantum Electrodynamics Near a Photonic Band Gap: Photons Bound States
and Dressed Atoms'', S. John and J. Wang, Phys. Rev. Lett. 64,
2418 (1990). ABSTRACTPDF
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''Nonlinear Optical Solitary Waves in a Photonic Bandgap'', S. John and
N. Akozbek, Physical Review Letters 71, 1168 (1993). ABSTRACTPDF
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''Topological Magnetic Solitons in the Two-Dimensional Mott-Hubbard Gap'',
S. John and A. Golubentsev, Physical Review Letters 71, 3343
(1993). ABSTRACTPDF
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"Spontaneous Emission near the Edge of a Photonic Bandgap", Sajeev John
and Tran Quang, Physical Review A 50 1764 (1994). ABSTRACTPDF
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"Spin-flux and Magnetic Solitons in an Interacting Two-Dimensional Electron
Gas: Topology of Two-Valued Wavefunctions", Sajeev John and A. Golubentsev,
Physical
Review B51, 381 (1995). ABSTRACTPDF
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''Localization of Superradiance near a Photonic Bandgap'', S. John and
T. Quang, Phys. Rev. Lett. 74, 3419 (1995). ABSTRACTPDF
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''Optical Coherence Propagation and Imaging in a Multiple Scattering Medium'',
S. John, G. Pang and Y. Yang, Journal of Biomedical Optics 1,
number 2, 180 (1996). ABSTRACT
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''Quantum Optical Spin-Glass State of Impurity Two-Level Atoms in a Photonic
Bandgap'', S. John and T. Quang, Phys. Rev. Lett. 76, 1320
(1996). ABSTRACTPDF
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''Resonant Nonlinear Dielectric Response in a Photonic Band Gap Material'',
S. John and T. Quang, Phys. Rev. Lett. 76, 2484 (1996). ABSTRACTPDF
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''Theory of Lasing in a Multiple Scattering Medium'', S. John and G. Pang,
Physical
Review A 54, 3642 (1996). ABSTRACTPDF
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"Collective Switching and Inversion without Fluctuation of Two-Level Atoms
in Confined Photonic Systems", Sajeev John and Tran Quang, Physical
Review Letters 78, 1888 (1997). ABSTRACTPDF
POSTSCRIPT
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"Multi-photon Localization and Propagating Quantum Gap Solitons in a Frequency
Gap Medium", Sajeev John and Valery Rupasov, Physical Review Letters
79,
821 (1997). ABSTRACTPDF
POSTSCRIPT
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"Coherent Control of Spontaneous Emission Near a Photonic Band Edge: A
Single-Atom Optical Memory Device", Tran Quang, M. Woldeyohannes, Sajeev
John and G.S. Agarwal, Physical Review Letters 79 5238 (1997).
ABSTRACTPDF
POSTSCRIPT
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"Frozen Light", Sajeev John, Nature 390, 661 (1997). ABSTRACT
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"Charged Bosons in a Doped Mott Insulator: Electronic Properties of Domain
Wall Solitons and Meron-Vortices", Mona Berciu and Sajeev John, Physical
Review B 57 9521 (1998). ABSTRACTPDF
POSTSCRIPT
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"Midgap States of a Two-Dimensional Antiferromagnetic Mott Insulator: Electronic
Structure of Meron-Vortices", Sajeev John, Mona Berciu and A. Golubentsev,
Europhysics
Letters 41 (1), 31 (1998). ABSTRACTPDF
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"Photonic Band Gap Formation in Certain Self-Organizing Systems", Kurt
Busch and Sajeev John, Physical Review E 58, 3896 (1998).
ABSTRACTPDF
POSTSCRIPT
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"Liquid Crystal Photonic Band Gap Materials: The Tunable Electromagnetic
Vacuum", Kurt Busch and Sajeev John, Physical Review Letters 83
(5), 967-970 (1999).ABSTRACTPDF
POSTSCRIPT
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