ITAMP WorkshopA MiniSymposium onCoherent ControlOrganizer: Moshe ShapiroAugust 2829, 2000 


Dr. N. Balakrishnan Prof. Nicholas P. Bigelow Prof. Paul W. Brumer Prof. Jianshu Cao Dr. Michael Fleischhauer
Prof. Robert Gordon Dr. Misha Ivanov Prof. Jeffrey L. Krause Dr. Mikhail Lukin Mr. Brett Pearson Stuart A. Rice
Dr. Hossein Sadeghpour Prof. Moshe Shapiro David Tannor Dr. Ami Vardi 
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Fleischhauer  
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Controlled Nanoscale Deposition and Controlled Chaotic Quantum DiffusionPaul Brumer University of Toronto

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Quantum Coherence in Nonlinear Optical Processes

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Coherent Control of Photon Propagation: DarkState Polaritons and Quantum Memory for LightMichael Fleischhauer Photons are the fastest, most robust and readily available carriers of quantum information. But this information is hard to store and to process. A technique for a lossfree and reversible transfer of the quantum state of photon wavepackets to collective atomic excitations based on darkstate polaritons is described. Darkstate polaritons consist of electromagnetic and atomic spinwave components whose mixture can be externally controlled. Adiabatically changing the mixture between spinwave and elm. components allows to decellerate or accelerate and reshape the photon wavepacket. In particular the light pulse can be brought to a full stop and its quantum state is transferred to a collective atomic excitation. Reversing the process regenerates the photon wavepacket. Limitations and applications of the adiabatic transfer technique for quantum memories and quantum information transfer are discussed. 
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Alignment Is Forever  and Orientation too: Molecules in Combined Static Electric and Pulsed Nonresonant Radiative FieldsLong Cai, Jotin Marango, and Bretislav Friedrich

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Using the Phase of Light as a Photochemical ToolRobert J. Gordon
Tamar Seideman

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Ultrashort Pulses and Control of Molecular Rotations: from Taming Molecules to Pulse CompressionMisha Ivanov
Femtosecond pulses offer two approaches to quantum control, based on using pulse shaping techniques and/or strong electric fields. Both are combined in strong field molecular optics to align molecules and force controlled molecular rotations up to rotational dissociation threshold. If time permits, I also hope to speculate on how control over molecular rotations, combined with feedback learning algorithms, can be used to generate and deliver through dispersive media single intense 12 fs pulses. 
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PhotoGalvanoMechanical Phenomena in
Nanotubes

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Selective Population Transfer with Intense, Chirped Laser PulsesJeffrey L. Krause and Vladimir S. Malinovsky University of Florida We consider population transfer by adiabatic rapid passage
with intense, chirped laser pulses. Using a dressedstate picture,
we analyze the effects of the chirp rate, intensity and frequency
detuning. We demonstrate that chirped pulses and transformlimited
pulses differ considerably with respect to both the efficiency
and robustness of the transfer they affect. Finally, two schemes
for selective population transfer are presented. The first uses
a single 
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Quantum Control of Interacting Atoms andMesoscopic Ensembles: Towards Fast, Robust andScalable Quantum Logic GatesMikhail Lukin
Deterministic entanglement of coupled quantum systems (qubits) as well as its scalability to manyqubit systems are the main challenges in experimental quantum information science. As a rule, an exceptional degree of quantum control over internal (e.g. electronic) and external (e.g. motional) degrees of freedom is required to implement the socalled quantum logic operations. We discuss several schemes for implementing fast and robust
qubit entanglement. The schemes are based on neutral atoms interacting
via electric dipoledipole coupling. We identify the main sources
of decoherence and errors and discuss several approaches to mitigate
their influence. Specific implementations of these ideas include
optically excited single atoms (impurities) in the condensed
phase and cold atoms trapped in optical lattices and excited
into low lying Rydberg states. Furthermore, we show how the combination
of The present approach eliminates stringent requirements on
precise control of atomic position and motion, and allows for
entanglement of distantly separated qubits thereby facilitating

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Using an Adaptive Algorithm to Learn About Quantum SystemsJ. L. White, B. J. Pearson, T. C. Weinacht, and P. H. Bucksbaum Physics Department, University of Michigan We have constructed an adaptive learning algorithm to control quantum systems. By directing intense shaped ultrafast laser pulses into a variety of samples and using a measurement of the system as a feedback signal, we are able to reshape the laser pulses to direct the quantum system into a desired physical state. The algorithm programs a computercontrolled, acoustooptic modulator (AOM) pulse shaper. The learning algorithm generates new shaped laser pulses based on the success of previous pulses in achieving a predetermined goal. In addition, the algorithm itself evolves in order to arrive at the solution in the most efficient manner. 
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Coherent Control of Asymmetric Synthesis and the Photoassociation of Ultracold AtomsMoshe Shapiro Chemical Physics Department We present a laserbased method of increasing the enantiomeric excess of a chiral enantiomer in a racemic mixture[1]. Neither the initial reagents nor the incident light need be chiral. Both formal and computational results show that enhancement of the enantiomer of choice, controlled by laser parameters, can be extensive. Extension of the method to treating chiral molecule purification in homogeneous media and in the presence of relaxation are then discussed. Computations for specific molecules are presented. In the second part of the talk we present a time dependent theory for photoassociation induced by strong pulses[2]. Both the pumpbeforedump "intuitive" and dumpbeforepump "counterintuitive" schemes are considered. Resonantlyenhanced twophoton association of ultracold atoms is shown to be an efficient mechanism for the production of ultracold molecules. We have performed detailed calculations on the radiative recombination of cold Na atoms by short laser pulses. Our calculations show that, per pulse, it is possible for up to 97% of all headon NaNa colliding pairs to end up as v=0, J=0 translationally cold Na_{2} molecules. These predictions were recently[3] confirmed experimentally in BEC. References [1] M. Shapiro, E. Frishman, and P. Brumer, "Coherently Controlled Asymmetric Synthesis with Achiral Light" Phys. Rev. Lett. 84 1669 (2000). [2] A.. Vardi, D. G. Abrashkevich, E. Frishman and M. Shapiro, "Theory of Radiative Recombination with Strong Laser Pulses and the Formation of Ultracold Molecules via Stimulated PhotoRecombination of Cold Atoms" J. Chem. Phys. 107 6166 (1997). A. Vardi, M. Shapiro and K. Bergmann, "Complete Population
Transfer to and from a Continuum and the Radiative Association
of Cold Na Atoms to Produce Translationally Cold Na2 Molecules
in Specific VibRotational States." Optics Express 4,
91 [3] R. Wynar, R.S. Freeland, D.J. Han, C.Ryu and D.J. Heinzen, Science 287, 1016 (2000) 
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Laser Cooling of Molecules:

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Dynamics And Control Of A TwoMode BoseEinstein
Condensate Amichay Vardi and James R. Anglin
The twomode model has been widely used to describe the rich
dynamics of a BoseEinstein condensate (BEC) in a doublewell
potential and a BEC with two radiativelycoupled internal (typically
spin) states. The vast majority of these studies employ meanfield
theory (MFT), decorrelating the ensemble at the lowest level
of the BBGKY hierarchy of expectation value equations of motion,
by approximating secondorder moments in term of first order
moments. MFT is essentially a semiclassical approximation for
the quantum field operators, with the inverse square root of
the number N of particles playing the role of \hbar as a perturbative
parameter. Since in current BEC experiments N is indeed large,
MFT is generally an excellent approximation and it is difficult
to observe qualitatively significant quantum corrections. However,
in the vicinity of a dynamical instability of MFT, quantum corrections
appear on timescales that grow only logarithmically with N.
The twomode model has exactly such an unstable point, corresponding
to the Josephson /pi state in the doublewell case. Using a Blochsphere
picture for the reduced single particle density matrix The MFT dynamical instability has significant implications on the 'stateengineering' and control of the twomode condensate. Conventional /pipulse techniques are hard to implement in the presence of interactions, since the shape of the wave function, as well as the levelenergies change as population is being transferred from one level to another, making it difficult to maintain the resonance. Adiabatic passage, on the other hand, becomes highly sensitive to the direction of the sweep (from negative to positive detuning or viseversa) since this determines whether the evolving adiabatic eigenstate would pass through the unstable state or not. Assuming repulsive interactions, we show that beyond a critical value of the interaction strength, corresponding to the formation of the instability, adiabaticity can not be maintained with a negative sweep, no matter how slowly the resonance is traversed (The same is true for attractive interactions and a positive sweep). The collapse of adiabaticity is motivated by the MFT instability as well as by the high quasiparticle production rate near that point. 
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All sessions will be held in the Classroom in Building A, Room 101 
Monday, August 28, 2000 

Session I. Quantum Control 

9:00 a.m.  S. Rice: Variations on the Theme of STIRAP 
9:40 a.m.  R. Gordon: Using the Phase of Light as a Photochemical Tool 
10:20 a.m.  Coffee 
Session II. Wavepacket Control 

10:40 a.m.  B. Pearson: Using an Adaptive Algorithm to Learn About Quantum Systems 
11:20 a.m.  N. Balakrishnan: Production of Excited Iodine and the Control of I*/I Branching Ratio in the Photodissociation of NaI 
12:00 noon  Lunch 
Session III. Photonic Control and Entanglement 

1:30 p.m.  M. Lukin: Quantum Control of
Interacting Atoms and Mesoscopic Ensembles: Towards Fast, Robust and Scalable Quantum Logic Gates 
2:10 p.m.  M. Fleischhauer: Coherent Control of Photon Propagation: DarkState Polaritons and Quantum Memory for Light 
2:50 p.m.  Refreshments 
Session IV. Control in Condense Phase I 

3:20 p.m.  P. Brumer: Bichromatic Coherent
Control: Controlled Nanoscale Deposition and Controlled Chaotic Quantum Diffusion 
4:00 p.m.  J. Krause: Selective Population
Transfer with Intense, Chirped Laser Pulses 
5:00 p.m. Reception in 3rd Floor Perkin Bridge 
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Tuesday, August 28, 2000 

Session V. Control in Condense Phase II 

9:00 a.m.  J. Cao: Quantum Coherence in Nonlinear Optical Processes 
9:40 a.m.  P. Kral: PhotoGalvanoMechanical Phenomena in Nanotubes 
10:20 a.m.  Coffee 
Session VI. Coherent Cooling and Trapping I 

10:40 a.m.  A. Vardi: Dynamics and Control of a TwoMode BoseEinstein Condensate Beyond MeanField Theory 
11:20 a.m.  D. Tannor: Laser Cooling of Molecules: A Theory of Purity Increasing Transformations 
12:00 noon  Lunch 
Session VII. Coherent Cooling and Trapping II 

1:30 p.m.  N.
Bigelow: Formation of Homo and Heteronuclear Ultracold
Molecules 
2:10 p.m.  M. Shapiro: Coherent Control of Asymmetric Synthesis and the Photoassociation of Ultracold Atoms 
2:50 p.m.  Refreshments 
Session VIII. Strong Fields 

3:10 p.m.  M. Ivanov: Ultrashort Pulses
and Control of Molecular Rotations: From Taming Molecules to Pulse Compression 
3:50 p.m.  B. Friedrich: Alignment Is Forever  and Orientation too: Molecules in Combined Static Electric and Pulsed Nonresonant Radiative Fields 
4:30 p.m.  Summary 
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