160 research outputs found
Reply on `comment on our paper `Single two-level ion in an anharmonic-oscillator trap: Time evolution of the Q function and population inversion ''
We show here that the model Hamiltonian used in our paper for ion vibrating
in a q-analog harmonic oscillator trap and interacting with a classical
single-mode light field is indeed obtained by replacing the usual bosonic
creation and annihilation operators of the harmonic trap model by their
q-deformed counterparts. The approximations made in our paper amount to using
for the ion-laser interaction in a q-analog harmonic oscillator trap, the
operator F_{q}=exp{-(|\epsilon|^2}/2)}exp{i\epsilon A^{\dagger}}exp{i\epsilon
A}, which is analogous to the corresponding operator for ion in a harmonic
oscillator trap that is . In our article we do not claim to have diagonalized the
operator, , for which the basis states
|g,m> and |e,m> are not analytic vectors.Comment: Revtex, 4pages. To be Published in Physical Review A59, NO.4(April
99
Quantum integrability and Bethe ansatz solution for interacting matter-radiation systems
A unified integrable system, generating a new series of interacting
matter-radiation models with interatomic coupling and different atomic
frequencies, is constructed and exactly solved through algebraic Bethe ansatz.
Novel features in Rabi oscillation and vacuum Rabi splitting are shown on the
example of an integrable two-atom Buck-Sukumar model with resolution of some
important controversies in the Bethe ansatz solution including its possible
degeneracy for such models.Comment: Latex, 7 pages, 1 figure. Final version to be published in J Phys A
(as Letter
Schr\"{o}dinger cat state of trapped ions in harmonic and anharmonic oscillator traps
We examine the time evolution of a two level ion interacting with a light
field in harmonic oscillator trap and in a trap with anharmonicities. The
anharmonicities of the trap are quantified in terms of the deformation
parameter characterizing the q-analog of the harmonic oscillator trap.
Initially the ion is prepared in a Schr\"{o}dinger cat state. The entanglement
of the center of mass motional states and the internal degrees of freedom of
the ion results in characteristic collapse and revival pattern. We calculate
numerically the population inversion I(t), quasi-probabilities and
partial mutual quantum entropy S(P), for the system as a function of time.
Interestingly, small deformations of the trap enhance the contrast between
population inversion collapse and revival peaks as compared to the zero
deformation case. For \beta =3 and determines the average number
of trap quanta linked to center of mass motion) the best collapse and revival
sequence is obtained for \tau =0.0047 and \tau =0.004 respectively. For large
values of \tau decoherence sets in accompanied by loss of amplitude of
population inversion and for \tau \sim 0.1 the collapse and revival phenomenon
disappear. Each collapse or revival of population inversion is characterized by
a peak in S(P) versus t plot. During the transition from collapse to revival
and vice-versa we have minimum mutual entropy value that is S(P)=0. Successive
revival peaks show a lowering of the local maximum point indicating a
dissipative irreversible change in the ionic state. Improved definition of
collapse and revival pattern as the anharminicity of the trapping potential
increases is also reflected in the Quasi- probability versus t plots.Comment: Revised version, 16 pages,6 figures. Revte
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The sea ice model component of HadGEM3-GC3.1
A new sea ice configuration, GSI8.1, is implemented in the Met Office global coupled configuration HadGEM3-GC3.1 which will be used for all CMIP6 (Coupled Model Intercomparison Project Phase 6) simulations. The inclusion of multi-layer thermodynamics has required a semi-implicit coupling scheme between atmosphere and sea ice to ensure the stability of the solver. Here we describe the sea ice model component and show that the Arctic thickness and extent compare well with observationally based data
Mindfulness based cognitive therapy for young people and their carers: A mixed-methods feasibility study
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.We aimed to evaluate whether Mindfulness Based Cognitive Therapy (MBCT) was feasible and acceptable for
young people, their parents and the clinicians working with them; whether a parallel course for parents was a useful
addition; and whether attendance at MBCT was associated with improved outcomes. The design was a mixed
methods service evaluation of an eight session MBCT programme for young people who were recovering from
depression. The course was a manualised eight session group intervention. Both young people (n=18) and parents
(n=21) completed validated measures before and after the course. Semi-structured interviews were completed with
some group participants and clinical staff working in the service. Care records were searched for additional contact
following the intervention. Qualitative data from young people, parents and clinicians suggested that MBCT was
acceptable and feasible, and provided strategies to cope. The parent course was reported to provide personal support
to parents and helped them cope with their childâs depression while also impacting the family, promoted shared
understanding of depression and strategies to combat it, and addressed intergenerational aspects of depression. 84%
of participants attended at least 6/8 sessions and 48% required no further intervention within the following year.
Young people had statistically significant improvements across all outcome measures, while parents had statistically
significant improvements in rumination, self-compassion and decentering.Daniel Racey completed this work whilst supported by an NIHR Academic Clinical Fellowship while Kelly
Blockley and Vashti Berry are supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula
Quantum integrable multi atom matter-radiation models with and without rotating wave approximation
New integrable multi-atom matter-radiation models with and without rotating
wave approximation (RWA) are constructed and exactly solved through algebraic
Bethe ansatz. The models with RWA are generated through ancestor model approach
in an unified way. The rational case yields the standard type of
matter-radiaton models, while the trigonometric case corresponds to their
q-deformations. The models without RWA are obtained from the elliptic case at
the Gaudin and high spin limit.Comment: 9 pages, no figure, talk presented in int. conf. NEEDS04 (Gallipoli,
Italy, July 2004
Determination of entangled quantum states of a trapped atom
We propose a method for measuring entangled vibronic quantum states of a
trapped atom. It is based on the nonlinear dynamics of the system that appears
by resonantly driving a weak electronic transition. The proposed technique
allows the direct sampling of a Wigner-function matrix, displaying all knowable
information on the quantum correlations of the motional and electronic degrees
of freedom of the atom. It opens novel possibilities for testing fundamental
predictions of the quantum theory concerning interaction phenomena.Comment: 7 pages, 3 figures, to be published in Phys. Rev. A 56 (Aug
Detection of BRAF mutations in the tumour and serum of patients enrolled in the AZD6244 (ARRY-142886) advanced melanoma phase II study
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Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5°N
The RAPID-MOCHA array has observed the Atlantic Meridional overturning circulation (AMOC) at 26.5°N since 2004. During 2009/2010, there was a transient 30% weakening of the AMOC driven by anomalies in geostrophic and Ekman transports. Here, we use simulations based on the Met Office Forecast Ocean Assimilation Model (FOAM) to diagnose the relative importance of atmospheric forcings and internal ocean dynamics in driving the anomalous geostrophic circulation of 2009/10. Data assimilating experiments with FOAM accurately reproduce the mean strength and depth of the AMOC at 26.5°N. In addition, agreement between simulated and observed stream functions in the deep ocean is improved when we calculate the AMOC using a method that approximates the RAPID observations. The main features of the geostrophic circulation anomaly are captured by an ensemble of simulations without data-assimilation. These model results suggest that the atmosphere played a dominant role in driving recent interannual variability of the AMOC
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