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General QQQ Posters
Posters submitted by QQQ members, for distribution on this site.
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1. Diffraction of Bose-
Einstein Condensates
Nottingham, Melbourne, Otago
Recently, Bose-Einstein condensates (BECs) have been diffracted from surface based wire arrays. To make further progress with such
atom optics devices, it is essential to understand the role of the atomic interactions when BECs are used in this context. These
interactions often give rise to interesting physics but can also ruin attempts to coherently control condensates.
Full poster download
NMO_bose_poster.pdf
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QQQ Prize Winning Posters
QQQ sponsors prizes for posters that are presented at conferences whose subjects
areas have significant overlap with those of the QQQ. The QQQ prize is awarded to the best student poster
"most clearly communicating exciting new developments in the field of Quantum
Information, Quantum Control and Quantum Optics". The past winners are presented on this page with links to their research groups. For
information on future QQQ poster prizes see Upcoming Events.
Endohedral Fullerenes and ODMR Spectroscopy for Endohedral Fullerenes
A Tiwari1, A A R Watt1, R A Taylor2, K Porfyrakis A Ardavan2 and G A D Briggs1
1. QIPIRC, Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH.
2. Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PY
We propose endohedral fullerene based quantum computation using the endohedral spin state to encode quantum information. The ensemble readout of spin can be performed using electron spin resonance (ESR). This technique is senstive enough to reveal the spin activity but it is not suitable for single spin readout which is a prerequiste for most quantum algorithms.
Fullerenes are symmetric, nearly spherical
hollow cages of carbon atoms. The space within
the cage is large enough to accommodate one
or more atoms or small clusters. The resultant
structure is called an endohedral fullerene:
e.g.
N@C60, P@C60, La@C60, Sc2@C82 , Er3N@C80,
ErSc2 N@C80 etc.
Above: Experimental setup for PL and PLE of endohedral fullerenes
Full poster download
ArchanaTiwari.pdf
Rapid state purification of a superconducting charge qubit
E. J. Griffith1, C. D. Hill1, J. F. Ralph1, K. Jacobs2 and H. M. Wiseman3
1. The Department of Electrical Engineering and Electronics, The University of Liverpool. United Kingdom.
2. The Department of Physics and Astronomy, Louisiana State University. United States.
3. Centre for Quantum Computer Technology, Griffith University. Australia.
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Above: Ideal feedback to the plane orthogonal to the measurement axis yields the fastest purification rate. However the perfect controls would be difficult to achieve in practice
arXiv Preprint
http://www.arxiv.org/abs/quant-ph/0610044
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Purification of a qubit by using weak measurement can be a time consuming process when the measurement strength is significantly reduced.
However it has been previously discovered that it is possible to accelerate the purification process by using quantum feedback. Where the maximum purification rate is obtained by placing the Bloch vector on the plane orthogonal to the measurement axis, prior to each measurement.
Unfortunately, the nature of the superconducting charge qubit makes the task of holding the Bloch vector within this plane very difficult.
Therefore we propose a feedback protocol which yields near optimal performance, by using only one control field with simple π-pulses.
Full poster download
EliasGriffith.ppt
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Local control of the quantum dynamics in multiple potential wells
Philipp Marquetand and Volker Engel.
Institut fur Physikalische Chemie, Am Hubland, 97074 Wurzburg, Germany.
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Above: The molecule under investigation is (R)-2-chloro- 5-methylcyclopenta-2, 4-dienecarbaldehyde, which was first used by
Fujimura et al. as a model system for triggered motor motion.
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The rotational motion of a molecular motor is investigated within the framework of local
control theory. Within this approach, the laser fields are constructed from the system's
dynamics at any instant of time. In this way, it is possible to
give the field a clear physical interpretation.
Here, the aim is to initiate either a clockwise or a counter-clockwise
rotation of a functional group in a molecule. We compare quantum and classical calculations, which exhibit the same basic features.
This strengthens the point that local control is as close to intuition as possible.
Full poster download
PhilippMarquetand.pdf
External Links:
Physical Chemistry AK Engel
Philipp Marquetand's home page
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Dynamical instability in a nanomechanical superconducting single electron transistor
J. Imbers, D.A. Rodrigues and A.D. Armour.
School of Physics and Astronomy, University of Nottingham, Nottingham, UK.
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When a superconducting single-electron transistor (SSET) is tuned to the vicinity of a transport resonance known as the
Josephson quasiparticle resonance it acts as an exquisitely sensitive electrometer. Thus when a nanomechanical
resonator is coupled electrostatically to the SSET as a movable gate the SSET can be used to
monitor the position of the resonator with almost quantum-limited precision.
However, Heisenberg's Uncertainty
principle dictates that all measurements must disturb the object of measurement. For the SSET-resonator system
the back-action of the SSET on the resonator depends very sensitively on how the SSET is operated: under
some circumstances, the SSET acts on the resonator like a thermal bath with a surprisingly low effective
temperature. In contrast, for a different choice of SSET operating point, the SSET can drive the resonator into an
instability. In this poster we explore the nature of this instability.
For more infomation see the preprint:
http://xxx.soton.ac.uk/abs/cond-mat/0608166
Full poster download
JaraImbers.ppt
Images Wigner functions of resonator steady state with different ΔE, the energy gain of Cooper pairs:
Top: ΔE = 0.1, system in thermal state; Middle: ΔE = -0.1, system in limit cycle; Bottom: ΔE = -0.16, system has bistability.
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