825 research outputs found
Reservoir engineering of a mechanical resonator: generating a macroscopic superposition state and monitoring its decoherence
A deterministic scheme for generating a macroscopic superposition state of a
nanomechanical resonator is proposed. The nonclassical state is generated
through a suitably engineered dissipative dynamics exploiting the
optomechanical quadratic interaction with a bichromatically driven optical
cavity mode. The resulting driven dissipative dynamics can be employed for
monitoring and testing the decoherence processes affecting the nanomechanical
resonator under controlled conditions.Comment: 10 pages, 7 figure
Phonon Josephson Junction with Nanomechanical Resonators
We study coherent phonon oscillations and tunneling between two coupled
nonlinear nanomechanical resonators. We show that the coupling between two
nanomechanical resonators creates an effective phonon Josephson junction which
exhibits two different dynamical behaviors: Josephson oscillation (phonon-Rabi
oscillation) and macroscopic self-trapping (phonon blockade). Self-trapping
originates from mechanical nonlinearities, meaning that when the nonlinearity
exceeds its critical value, the energy exchange between the two resonators is
suppressed, and phonon-Josephson oscillations between them are completely
blocked. An effective classical Hamiltonian for the phonon Josephson junction
is derived and its mean-field dynamics is studied in phase space. Finally, we
study the phonon-phonon coherence quantified by the mean fringe visibility, and
show that the interaction between the two resonators may lead to the loss of
coherence in the phononic junction.Comment: Realization of Josephson junction at nano/optomechanical resonators.
Comments are welcome
Proceedings of the ECSCW'95 Workshop on the Role of Version Control in CSCW Applications
The workshop entitled "The Role of Version Control in Computer Supported Cooperative Work Applications" was held on September 10, 1995 in Stockholm, Sweden in conjunction with the ECSCW'95 conference. Version control, the ability to manage relationships between successive instances of artifacts, organize those instances into meaningful structures, and support navigation and other operations on those structures, is an important problem in CSCW applications. It has long been recognized as a critical issue for inherently cooperative tasks such as software engineering, technical documentation, and authoring. The primary challenge for versioning in these areas is to support opportunistic, open-ended design processes requiring the preservation of historical perspectives in the design process, the reuse of previous designs, and the exploitation of alternative designs.
The primary goal of this workshop was to bring together a diverse group of individuals interested in examining the role of versioning in Computer Supported Cooperative Work. Participation was encouraged from members of the research community currently investigating the versioning process in CSCW as well as application designers and developers who are familiar with the real-world requirements for versioning in CSCW. Both groups were represented at the workshop resulting in an exchange of ideas and information that helped to familiarize developers with the most recent research results in the area, and to provide researchers with an updated view of the needs and challenges faced by application developers. In preparing for this workshop, the organizers were able to build upon the results of their previous one entitled "The Workshop on Versioning in Hypertext" held in conjunction with the ECHT'94 conference. The following section of this report contains a summary in which the workshop organizers report the major results of the workshop. The summary is followed by a section that contains the position papers that were accepted to the workshop. The position papers provide more detailed information describing recent research efforts of the workshop participants as well as current challenges that are being encountered in the development of CSCW applications. A list of workshop participants is provided at the end of the report.
The organizers would like to thank all of the participants for their contributions which were, of course, vital to the success of the workshop. We would also like to thank the ECSCW'95 conference organizers for providing a forum in which this workshop was possible
Optomechanical detection of weak forces
Optomechanical systems are often used for the measurement of weak forces.
Feedback loops can be used in these systems for achieving noise reduction. Here
we show that even though feedback is not able to improve the signal to noise
ratio of the device in stationary conditions, it is possible to design a
nonstationary strategy able to improve the sensitivity.Comment: 12 pages, 6 figures, contribution to the proceedings of the SPIE
Conference on Fluctuations and Nois
Quantum state protection using all-optical feedback
An all-optical feedback scheme in which the output of a cavity mode is used
to influence the dynamics of another cavity mode is considered. We show that
under ideal conditions, perfect preservation against decoherence of a generic
quantum state of the source mode can be achieved.Comment: 10 pages, 4 figures, to appear in the Dan Walls Memorial Volume,
edited by H. Carmichael, R. Glauber, and M. Scully, to be published by
Springe
Proceedings of the Workshop on Versioning in Hypertext Systems
This report contains 9 papers presented at a workshop on version management and hypertext, as well as a summary introduction by the organizers. These papers address requirements, solutions, and research issues related to the management of hypertext databases. Version management is not only a key application requirement in some domains (like design journals and electronic manuals) but provides a way to preserve the integrity of links in a changing hyperbase
Suppression of Stokes scattering and improved optomechanical cooling with squeezed light
We develop a theory of optomechanical cooling with a squeezed input light
field. We show that Stokes heating transitions can be \emph{fully} suppressed
when the driving field is squeezed below the vacuum noise level at an
appropriately selected squeezing phase and for a finite amount of squeezing.
The quantum backaction limit to laser cooling can be therefore moved down to
zero and the resulting final temperature is then solely determined by the ratio
between the thermal phonon number and the optomechanical cooperativity
parameter, independently of the actual values of the cavity linewidth and
mechanical frequency. Therefore driving with a squeezed input field allows to
prepare nanomechanical resonators, even with low resonance frequency, in their
quantum ground state with a fidelity very close to one
Generation of two-mode entangled states by quantum reservoir engineering
A method for generating entangled cat states of two modes of a microwave
cavity field is proposed. Entanglement results from the interaction of the
field with a beam of atoms crossing the microwave resonator, giving rise to
non-unitary dynamics of which the target entangled state is a fixed point. We
analyse the robustness of the generated two-mode photonic "cat state" against
dephasing and losses by means of numerical simulation. This proposal is an
instance of quantum reservoir engineering of photonic systems.Comment: 8 pages, 7 figure
- …