31 research outputs found
Persistent entanglement in two coupled SQUID rings in the quantum to classical transition - A quantum jumps approach
We explore the quantum-classical crossover of two coupled, identical,
superconducting quantum interference device (SQUID) rings. The motivation for
this work is based on a series of recent papers. In ~[1] we showed that the
entanglement characteristics of chaotic and periodic (entrained) solutions of
the Duffing oscillator differed significantly and that in the classical limit
entanglement was preserved only in the chaotic-like solutions. However, Duffing
oscillators are a highly idealised toy system. Motivated by a wish to explore
more experimentally realisable systems we extended our work in [2,3] to an
analysis of SQUID rings. In [3] we showed that the two systems share a common
feature. That is, when the SQUID ring's trajectories appear to follow (semi)
classical orbits entanglement persists. Our analysis in[3] was restricted to
the quantum state diffusion unravelling of the master equation - representing
unit efficiency heterodyne detection (or ambi-quadrature homodyne detection).
Here we show that very similar behaviour occurs using the quantum jumps
unravelling of the master equation. Quantum jumps represents a discontinuous
photon counting measurement process. Hence, the results presented here imply
that such persistent entanglement is independent of measurement process and
that our results may well be quite general in nature.Comment: 6 pages, 3 figures. Published as part of a special issue for the 11th
International Conference on Squeezed States and Uncertainty Relations/4th
Feynman festival in Olomouc 2009 (This paper extends the results presented in
arXiv:0909.4488
Frequency-resolved Monte Carlo
We adapt the Quantum Monte Carlo method to the cascaded formalism of quantum optics, allowing us to simulate the emission of photons of known energy. Statistical processing of the photon clicks thus collected agrees with the theory of frequency-resolved photon correlations, extending the range of applications based on correlations of photons of prescribed energy, in particular those of a photon-counting character. We apply the technique to autocorrelations of photon streams from a two-level system under coherent and incoherent pumping, including the Mollow triplet regime where we demonstrate the direct manifestation of leapfrog processes in producing an increased rate of two-photon emission events
Towards quantum computing with single atoms and optical cavities on atom chips
We report on recent developments in the integration of optical
microresonators into atom chips and describe some fabrication and
implementation challenges. We also review theoretical proposals for quantum
computing with single atoms based on the observation of photons leaking through
the cavity mirrors. The use of measurements to generate entanglement can result
in simpler, more robust and scalable quantum computing architectures. Indeed,
we show that quantum computing with atom-cavity systems is feasible even in the
presence of relatively large spontaneous decay rates and finite photon detector
efficiencies.Comment: 14 pages, 6 figure
Integrin ÎČ1 is required for the invasive behaviour but not proliferation of squamous cell carcinoma cells in vivo
Integrin ÎČ1 is both overexpressed and in an âactive' conformation in vulval squamous cell carcinomas (VSCCs) compared to matched normal skin. To investigate the significance of integrin ÎČ1 deregulation we stably knocked-down integrin ÎČ1 expression in the VSCC cell line A431. In vitro analysis revealed that integrin ÎČ1 is required for cell adhesion, cell spreading and invasion. However, integrin ÎČ1 is not required for cell growth or activation of FAK and ERK signalling in vitro or in vivo. Strikingly, while control tumours were able to invade the dermis, integrin ÎČ1 knockdown tumours were significantly more encapsulated and less invasive
From Clock Synchronization to Dark Matter as a Relativistic Inertial Effect
Lecture at BOSS2011 on relativistic metrology, on clock synchronization,
relativistic dynamics and non-inertial frames in Minkowski spacetime, on
relativistic atomic physics, on ADM canonical tetrad gravity in asymptotically
Minkowskian spacetimes, on the York canonical basis identifying the inertial
(gauge) and tidal degrees of freedom of the gravitational field, on the
Post-Minkowskian linearization in 3-orthogonal gauges, on the Post-Newtonian
limit of matter Hamilton equations, on the possibility to interpret dark matter
as a relativistic inertial effect connected with relativistic metrology (i.e.
clock synchronization) in Einstein GR.Comment: 90 pages. Lecture at BOSS201
Macroscopic dark periods without a metastable state.
Published versio