Physicists produce first antiatom

Faced with dimming prospects on Earth, particle physicists are turning to projects in
space.  An antimatter detector and a new gamma ray telescope may be the
first of a flock.

    /*---------------------------------------------------------------------*/
 
Physicists produce first antiatom
CERN created first few antiatoms.  Lowenergy
antiproton ring.  11 atoms of antihydrogen
made.  First complete antiatom.
Antimatter is the mirror image of the matter that makes up
our world.  Its existence was suggested by British theorist
Paul Dirac in 1931.  Dirac theorized that
this particle the positron would have the same mass as
the electron but opposite charge, and two would annihilate on contact.
The positron was ound 2 years later.  Until now noone
could combine positron and antiproton to make
antihydrogen, Direct a jet of xenon gas across the
path of LEAR's antiproton beam.  Occasionally an antiproton is
scattered by the positive charge of a xenon nucleus , converting
part of its energy into an electron-positron pair.
In a fraction of these, the positron's velocity was sufficiently close
to that of the scattered antiproton for the two particles to
combine and create an anti hydrogen atom.

    /*---------------------------------------------------------------------*/
 
Selector Genes, Polymorphisms and Evolution
Selector genes, master regulators of other
genes, originally proposed to define restricted areas in the developing fly called
compartments.  Although this idea of selector genes
is now embedded in genes, special
utility when the evolution of developmental processes is considered.
Selector genes activate realizator genes.  which build the
anatomical structures of the adult body.  Ectopic
expression of a selector gene can reprogram a compartment.


    /*---------------------------------------------------------------------*/
 
Approaching the Quantum Gate
The familiar desktop computer is based on a logic of 1's and 0's
that defines a particular set of computations.  Deutch
contributed to the creation of a new theortical field
of quantum computation 10 years ago.  In which
binary logic is replace by fundamental computing elements that
follow the laws of quantum mechanics,  Just as a physical quantum system 
may be described by superpositions of eigenstates, a quantum
computer works by processing superpositions of quantum bits of "qubits"
    The field lay dormant until a discovery by
Shor that quantum computers may be capable of rapidly factoring large prime numbers,
a task that is fiendishly difficult on conventional computers
and so forms the basis for much
present-day cryptographic data security.
Unfortunately, for those desiring a quick
way to crack codes, experimental realization of 
a quantum computer will present
some extreme challenges.  Nevertheless
recent work by Turchette and Monroe
show that process is being made.
     Turchette have explored the
possibility of implementing a quantum
clogic element in the form of a cavity resonator containing a single cesium atom
interacting with individual photons.
The cesium,, prepared by optical pumping of an atomic beam
can either stayin the ground state or absorb circularly
polarized light.  A strong beam
of light entering the cavity modified
the way a probe beam interacts with the atom.
The result is an intesity - dependent phase shift between the
left and right circular components of the probe beam
that gives rise to conditional qunatum dynamics,
thus laying the foundation for photonic qunatum
logic circuits.  Instead of a beam of atoms, Monroe et al,
make use of a single trapped beryllium atom to
construct their prototype quantum logic gate.  The result is a two-bit
controlled "not" quantum gate,
which, when combined with single-bit operations, is
the basis for a universal logic element.
     now that quantum gates can be built,
crucial issues related to tthe decoherence
produced when quantum logic elements 
interact with the real world can be studied.
Though a working quantum computer is far off, these experiemtnal results
are encouraging and move quantum logic from
the realm of theory onto the benchtop.


    /*---------------------------------------------------------------------*/
 
Quantum Engineering of Optical Nonlinarities

    SEcond-order optical nonlinaerities in materials are of
paramount important for optical
wavelength conversion techniques, which are the basis 
of new high-resolution spectroscopic tools.  Semiconductor technology now makes it
possible to design and fabricate articificially asymmetric
quantum structures in which optical nonlinearities
can be calculated and optimized from first principles.  Extremely large
second-order susceptibilities can be
obtained in these asymmetric quantum wells.  Moreover,
properties such as double resonance enhancement
or electric field control will open
the way to new devices, suc has fully solid-state optical
parametric oscillators.


--fin