
December 910, 2002
Proceedings of the 2002 Quantum Institute Workshop
The Quantum Institute Steering
Committee recently sponsored a Laboratorywide workshop on quantum information,
science, and technology to develop a
coordinated framework for quantum
information, science, and technology research. This framework
will enable us to promote quantum R&D more effectively to both internal
and external customers, as well as plant the seeds for future Laboratorywide
collaborations.
Howard Barnum 
Generalized
Entanglement for Applications in Quantum Information and Condensed
Matter 
"Entanglement" is a nonclassical
property of some states of quantum systems that are composed of
parts: the "local" state describing the parts viewed
individually looks "mixed," probabilistic, but the "global"
state is "pure," as definite as a quantum state can
be. The notion of entanglement is relative: it depends on a choice
of "local" subalgebra. We generalize the notion of entanglement
by considering as "generalized entangled" pure states
that are mixed when viewed according to restrictions more general
than "locality": restrictions to interaction and control
of the system via a Lie subalgebra of the algebra of all of its
operators. We discuss applications to quantum computation and condensed
matter systems.

Dana Berkeland 
Quantum
Information in Ion Traps 
Ion traps are indispensable tools
for studying quantum mechanical systems because they can tightly
confine single ions almost indefinitely. We are using a linear Paul
trap to test the statement the exact result of any arbitrary measurement
of a quantum mechanical system should be unpredictable. The results
of this test are important to interpreting the nature of information
in a quantum mechanical system. Additionally, we are developing
our system so that we may perform quantum logic operations in trapped
ions.

Dana Berkeland for
Malcolm Boshier 
Waveguide
Interferometry with BoseEinstein Condensates 
We are attempting to harness the tight
control over atoms provided by a BoseEinstein condensate to build
a waveguide atom interferometer. This device will be extremely sensitive
to any interaction that affects the energies of atoms, such as electromagnetic
fields, gravity and gravity gradients, and accelerations. The technology
can also be miniaturized, ultimately down to the level of an integrated
"atom chip" with dimensions of just a few millimeters,
which would make possible a new generation of ultrasensitive miniature
sensors. 
Gennady Berman 
Modeling
and Simulations of Quantum Computation and Quantum Measurement 
I will briefly overview our current
quantum research, plans and ideas on modeling and simulations of
quantum computation and quantum measurement. This will include:
perturbation theory for scalable quantum computation, magnetic resonance
force microscopy singlespin measurement, selfassembled quantum
computation, typeII quantum computation.

Robin BlumeKohout 
Decoherence
from an Unstable Environment 
Existing models of decoherence, applicable
to quantum information theory or to fundamental questions in quantum
dynamics, are based on integrable environments. In order to extend
these models to chaotic environments, we have studied an analytic
model involving an inverted harmonic oscillator. The results indicate
that chaotic environments may produce decoherence much faster than
integrable ones.

Diego Dalvit 
Decoherence
and Quantum Information 
In this talk I will give a short overview
of the research we are doing in TQC in the fields of decoherence
(including quantumclassical transition and quantum chaos) and quantum
information (including quantum discord, mutual information and redundancy).

Diego Dalvit 
BEC
Optics and Vacuum Fluctuations 
In this talk I will give a short overview
of the research we are doing in TQC in the fields of BEC optics
(including quantum measurement of cold atoms and atom interferometry)
and vacuum fluctuations physics (including static and dynamic Casimir
forces).

Michael Di Rosa 
(Forthcoming)
Experiments in LaserCooling Molecules 
The laser cooling of molecules to
microKelvin temperatures appears to be experimentally possible.
We plan to demonstrate the first Dopplercooling of molecules, targeting
at first the alkalineearth hydrides (e.g. BeH and CaH) which are
paramagnetic and have electronic bands analogous to the SP resonance
transitions of the routinelytrapped alkali atoms. Once trapped
and cooled, molecules will offer through their internal states a
far richer range of inquiry than possible with atoms, including
studies in the coherence of intramolecular modes and photodissociated
fragments. We will highlight our strategy, the project’s status,
and our future plans.

Gary Doolen 
Selfassembled
Quantum Computers and Hybrid Quantum Computers 
For the past decade molecular switches
and selfassembly techniques have been developed that produce uniform
planar molecular switch arrays (10**6 x 10**6). Optimal spincontaining
molecules are being designed with DARPA support that maximally decouple
from the environment and are being selfassembled by the same scientists
who made the molecular switch arrays.
What will be gained when classical and quantum computers are combined
to form hybrid computers? IBM plans to build a $5M/year research
center to exploit the potential of hybrid computers. Arrays of quantum
computers coupled by classical communication have been shown to
solve partial differential equations efficiently. Applications of
hybrid computers to problems of interest to LANL will be mentioned.
Decoherence and fabrication limitations may restrict the size of
quantum computers, yet much can be done with large arrays of these.

John Grondalski 
Fully
Entangled Fraction as an Inclusive Measure of Entanglement Applications 
Computing and interpreting mixed state
entanglement is a hard problem. We explore quantities that have
a direct relationship to measureable quantities in quantum information
science and may be easier to compute and interpret. One such quantity
is the fully entangled fraction which is related to the fidelity
of dense coding, teleportation, or entanglement swapping.

Holger Grube 
Toward
a Scaleable SolidState Quantum Computer 
We are investigating process steps
leading to a Kane architecture solidstate quantum computer (reference
1). We have performed hydrogen resist lithography, lowtemperature
silicon homoepitaxial growth and charge imaging in our ultrahigh
vacuum scanning tunneling microscope. These steps are necessary
to create, activate and verify the phosphorus qubit array.
Holger Grube, Geoffrey W. Brown, Joshua M. Pomeroy, Marilyn E. Hawley
(MST8)
Reference 1: B. Kane, Nature 393, 133 (1998)

James E. Gubernatis 
Simulating
Physical Systems on Quantum Computers 
If a large quantum computer existed
today, there are very few significant physical problems, quantum
or classical, that could be solved on such a computer. I will summarize
the work of our team to develop the necessary quantum algorithms
(networks) to simulate quantum systems efficiently of a quantum
computer. The results of the actual realization of one such algorithm
for a toy problem on a liquid state NMR quantum computer will be
shown.

Leonid Gurvits 
Quantum Entanglement and Classical
Complexity 
We discuss natural geometric questions
about entangled and separable states of bipartite quantum systems
and linear maps on these systems, and investigations on the classical
complexity of answering these questions.

Jack Horner 
Using
Automated TheoremProvers to Aid the Design of Efficient Compilers
for Quantum Computing 
Designing efficient highlevel language
compilers for quantum computers will require optimizing the mapping
of applicationsourcelevel instructions into the logic of quantum
entanglement (LQE, Zurek and Laflamme 1996; Julsgaard 2001). LQE
can be represented as a system of propositions (Birkhoff and von
Neumann 1936; Jauch 1968) that is isomorphic to an orthocomplemented,
weakly modular lattice defined on the subspaces of an infinitedimensional
Hilbert space (Akhiezer and Glazman, 1961; Cohen 1989). Discovering
efficient mappings from applicationsource to LQE will require identifying
efficient derivations of quantumlogic theorems. Automated quantumlogic
theoremprovers can significantly aid this discovery effort. I describe
what I believe to be a novel and very brief proof generated by an
automated backtracking (Dewar and Cleary 1990) theoremprover, bvn,
for Birkhoffvon Neumann quantum logic (Horner 2001).

Daniel F. V. James 
PhotonicsBased
Quantum Technology 
It is now generally realized that
the exploitation of fundamentally quantum mechanical phenomena can
enable significant, and in some cases, tremendous, improvement for
variety of tasks important to emergent technologies. Because of
decades of successes in the experimental demonstration of such fundamental
phenomena, quantum optics is playing a preeminent role in this endeavor;
indeed, many of the objectives of quantum technologies are inherently
suited to optics (e.g., communications, remote sensing), while others
may have a strong optical component (e.g., distributed quantum computing,
quantum repeaters). With our collaborators both within LANL and
at other institutions worldwide, we are exploring various aspects
of the development of photonicsbased quantum technologies, in particular:
entangled state preparation and characterization, high efficiency
single photon detectors and Bell state analysis of photon pairs;
optical based readouts for spinbased solid state quantum computers;
optical probes for quantum phenomena in semiconductors; and the
physics of cold trapped ions.

Victor Klimov 
Nanocrystal
Quantum Dots and Quantum Technologies 
Colloidal synthesis allows the fabrication
of almost monodisperse sub10 nm semiconductor nanoparticles, known
also as nanocrystal quantum dots (NQDs). Due to the extremely small,
quantumconfined dimensions, NQDs exhibit discrete, atomiclike
energy states that make them ideally suited for transferring the
quantumcontrol approaches, well established for atoms and molecules,
into the domain of condensedmatter systems. Similar to true atoms,
NQDs offer well defined narrow resonances with potentially long
dephasing times. In addition, they offer the advantage of tunability
of electronic structures and electronic interactions via size/shape/structure
control, not possible in actual atomic systems. Some potential applications
of NQDs in quantum technologies include: NQDs as a singlephoton
source, NQD biexcitons as an entangled photon source, and NQD dimers
for conditional logic operations.

Ivar Martin 
Quantum
Measurement in Condensed Matter 
We focus on the design and analysis
of efficient quantum measurement techniques for individual quantum
systems, mainly in condensed matter context. This includes electrical
and mechanical detection and measurement of spins, and realistic
displacement measurement schemes for mechanical objects, such as
cantilevers. Applications that we have in mind include qubit design
and readout protocols, ultrasensitive detection in atomic force
microscopy and related experimental techniques, and molecular vibrational
spectroscopy.

Peter Milonni 
Photon
Counting and Atmospheric Turbulence 
When laser radiation propagates in
the atmosphere its photon statistics is modified because of the
intensity scintillations caused by turbulence. We have found generally
good agreement between the photon counting statistics measured at
LANL and the generally accepted (but largely untested) theory that
presumes a lognormal distribution for the scintillations. More
generally we can in principle infer the distribution describing
the intensity scintillations from the measured photon counting distribution.

Jane E. Nordholt 
Quantum
Imaging and Metrology 
The unique paring of photons of produced
by parametric down conversion makes possible many new types of imaging
and metrology. We will discuss some of the ongoing developments
in these two areas.

Jane Nordholt
Kevin McCabe 
Quantum
Key Distribution 
Quantum Key Distribution (QKD) is
rapidly moving from experimental curiosity to practical applications.
We have QKD projects ranging from all fiber network system development
to freespace optical links to satellites. A brief overview of the
work being performed in these areas will be given.

Rolando D. Somma 
Nature
and Measure of Entanglement in QuantumPhase Transitions 
Characterizing and quantifying entanglement
of quantum states in manyparticle systems is at the core of a full
understanding of the nature of quantum phase transitions in matter.
Entanglement is a relative notion and, although many measures of
entanglement have been defined in the literature, assessing the
utility of those measures to characterize quantum phase transitions
is still an open problem. Our aim is to introduce measures, based
on a different concept of entanglement, which allows us to identify
the transition and possibly classify quantum critical points.

Daniel Steck 
Quantum
Dynamics of Nonlinear Systems 
My background is in the experimental
study of the quantum dynamics of classically chaotic systems. My
current interests build upon this background, and include the study
(both theoretical and experimental) of feedback control of quantum
systems, the quantumclassical transition, and nonlinear dynamics
of BoseEinstein condensates.

Toni Taylor 
Ultrafast
Coherent Manipulation of Condensed Phase Quantum Systems 
Coherent quantum control uses ultrafast
optical pulse shaping techniques to selectively excite materials
with the objective of preparing and manipulating specific electronic
and photonic quantum states. Although coherent control has been
implemented for atomic and molecular systems, its application to
solidstate systems remains relatively untouched, yet the ability
to coherently manipulate solids is of critical importance for building
future quantum electronic and photonic devices. We will describe
the development of the field of coherent control of solidstate
systems using shaped ultrafast optical pulses for preparation, manipulation
and interrogation of quantum wavepackets. We will explore a series
of increasingly complex materials systems (nonlinear optical crystals,
semiconductor quantum dots, and bulk materials) that will enable
us to transfer quantum information processing and control approaches
into the domain of condensed matter.

Eddy Timmermans 
Low
Density LiquidLike BECs 
Multicomponent BoseEinstein condensates
(BECs), atom optics and the use of optical lattice technology provide
promising avenues for future BEC research. I will emphasize the
remarkable prediction of dilute BECs with the liquidlike property
of a selfdetermined density. I would also like to share some speculations
on how such selfconfined BECs could be helpful in realizing atomlaser
applications.

Eddy Timmermans 
A
FeshbachResonant Entangler 
Optical lattices provide a possible
environment for the experimental realization of quantum computation.
We have been exploring a promising scheme for the entanglement of
trapped neutral atoms based on the magnetically controlled Feshbach
resonances.

David J. Vieira 
UltraSensitive
Detection Using Atom Trap Technology 
Using the isotopic selectivity and
high sensitivity of the atomic trapping process, we have pioneered
a coupled magnetooptical trap (MOT)—mass separator system
for the isotopic ratio determination of ^{135}Cs/^{137}Cs.
The system presently achieves an overall efficiency of 0.5%, an
isotopic selectivity of >10^{12}, a sample detection limit
of 10^{6} atoms, and an isotopicratio accuracy of 4% in
the determination of ^{137}Cs/^{135}Cs. This new
method has important applications to the areas of environmental
science, nonproliferation, and homeland defense. We will briefly
summarize this work and highlight future improvements/extensions
of the method.

Xinxin Zhao 
Quantum
Entanglement and Quantum Degenerate Matter Projects 
Recently, ultracold atoms have attracted
quite some interests in quantum computing. At Los Alamos, we have
been setting up an optical lattice experiment with the goal of studying
spin entanglement and decoherence effects in optically trapped cold
atoms. We have also successfully produced BoseEinstein Condesate
(BEC) in a separate experiment. We will present our latest ideas
and progress towards the quantum entanglement of cold neutral atoms
and BECs.


About the Workshop
Held at the Quantum Institute Briefing Center, about forty
participants attended 25 technical presentations consisting of brief overviews
of
current quantum research, plans and ideas for future research, and how
these could contribute
to defining the Quantum Institute framework. Following these presentations,
attendees formed into breakout
groups to discuss specific category areas.
Members of the Quantum Institute
Steering Committee are Richard Hughes, Manny Knill, Toni Taylor, Dave Vieira,
Wojciech Zurek, Pam French, and Judith Snow (chair).
