Dear colleagues,
this Wednesday we have a colloquium about
Superconducting structures for quantum computing, 28. April 2004
Gianni Blatter
Theoretical Physics, ETH Zuerich
"Quantum information holds the promise for novel cryptographic and
computational schemes. Their implementation requires new types of
`quantum' hardware which fulfills two conflicting requirements,
controllability and simultaneous protection from the environment. The
quantum optics-, solid state-, and NMR communities pursue major programs
with the goal to achieve quantum control on manmade structures. The
state of art involves assemblies of trapped ions performing specific
tasks (controlled NOT gate, simple algorithms), a tailored molecule
factorizing 15 via an NMR pulse sequence, the first measurement of an
individual spin on a quantum dot, and controlled gate operations in
superconducting structures. While these achievements look very
promising, further advances in design and fabrication are needed in
order to achieve the fault tolerance required for quantum computing.
Here, we concentrate on superconducting devices and discuss novel design
elements implemented in a charge- and flux-frustrated superconducting
qubit with tetrahedral symmetry. Important new features are a relaxed
fabricational constraint on the Josephson junctions and potentially long
decoherence times due to a quadratic noise-susceptibility. Also, this
device involves a simple idle state with a doubly degenerate ground
state which does not suffer from strong decoherence via phonon
radiation, one of the most dangerous sources of decoherence in
superconducting quantum devices."
See also http://www.physik.unizh.ch/teaching/kolloquium.html for details.
--
Prof. Dr. Andreas Schilling
Physik-Institut der Universität Zürich
Winterthurerstrasse 190
CH-8057 Zürich (Switzerland)
Phone: +41 1 635 57 91
Fax: +41 1 635 57 04
schilling(a)physik.unizh.ch
Dear colleagues,
for this week we have no colloquium planned.
The first colloquium of this semester will be held on
Wed, April 14:
Alexander Kosovichev
Stanford University
Sunquakes and Helioseismology
"The interior of the Sun is not transparent to electromagnetic
radiation, and thus it is not accessible by traditional astronomical
techniques. However, it is transparent to acoustic waves. These waves
are excited by turbulent convection near the solar surface, and
propagate through the interior. The properties of the waves, frequencies
and travel times, depend on physical conditions of the solar plasma
(temperature, density, chemical composition, flow velocity). Therefore,
measurements of the wave properties provide powerful diagnostic methods
for probing the stellar interior. I review the basic principles of
helioseismology, and present recent observational results from the SOHO
space mission and ground-based networks. In particular, I discuss the
structure of the energy-generating core, global circulation of the Sun,
and the mechanisms of sunspots and solar activity."
See also http://www.physik.unizh.ch/teaching/kolloquium.html for details.
--
Prof. Dr. Andreas Schilling
Physik-Institut der Universität Zürich
Winterthurerstrasse 190
CH-8057 Zürich (Switzerland)
Phone: +41 1 635 57 91
Fax: +41 1 635 57 04
schilling(a)physik.unizh.ch