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Search Results: 1 - 10 of 401410 matches for " M. Aspelmeyer "
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Quantum State Orthogonalization and a Toolset for Quantum Optomechanical Phonon Control
M. R. Vanner,M. Aspelmeyer,M. S. Kim
Physics , 2012, DOI: 10.1103/PhysRevLett.110.010504
Abstract: We introduce a method that can orthogonalize any pure continuous variable quantum state, i.e. generate a state $|\psi_\perp>$ from $|\psi>$ where $<\psi|\psi_\perp> = 0$, which does not require significant a priori knowledge of the input state. We illustrate how to achieve orthogonalization using the Jaynes-Cummings or beam-splitter interaction, which permits realization in a number of systems. Furthermore, we demonstrate how to orthogonalize the motional state of a mechanical oscillator in a cavity optomechanics context by developing a set of coherent phonon level operations. As the mechanical oscillator is a stationary system such operations can be performed at multiple times, providing considerable versatility for quantum state engineering applications. Utilizing this, we additionally introduce a method how to transform any known pure state into any desired target state.
Cooling-by-measurement and mechanical state tomography via pulsed optomechanics
M. R. Vanner,J. Hofer,G. D. Cole,M. Aspelmeyer
Physics , 2012, DOI: 10.1038/ncomms3295
Abstract: Observing a physical quantity without disturbing it is a key capability for the control of individual quantum systems. Such back-action-evading or quantum-non-demolition measurements were first introduced in the 1970s in the context of gravitational wave detection to measure weak forces on test masses by high precision monitoring of their motion. Now, such techniques have become an indispensable tool in quantum science for preparing, manipulating, and detecting quantum states of light, atoms, and other quantum systems. Here we experimentally perform rapid optical quantum-noise-limited measurements of the position of a mechanical oscillator by using pulses of light with a duration much shorter than a period of mechanical motion. Using this back-action evading interaction we performed both state preparation and full state tomography of the mechanical motional state. We have reconstructed mechanical states with a position uncertainty reduced to 19 pm, limited by the quantum fluctuations of the optical pulse, and we have performed `cooling-by-measurement' to reduce the mechanical mode temperature from an initial 1100 K to 16 K. Future improvements to this technique may allow for quantum squeezing of mechanical motion, even from room temperature, and reconstruction of non-classical states exhibiting negative regions in their phase-space quasi-probability distribution.
Establishing EPR-channels between Nanomechanics and Atomic Ensembles
K. Hammerer,M. Aspelmeyer,E. S. Polzik,P. Zoller
Physics , 2008, DOI: 10.1103/PhysRevLett.102.020501
Abstract: We suggest to interface nanomechanical systems via an optical quantum bus to atomic ensembles, for which means of high precision state preparation, manipulation and measurement are available. This allows in particular for a Quantum Non-Demolition Bell measurement, projecting the coupled system, atomic ensemble - nanomechanical resonator, into an entangled EPR-state. The entanglement is observable even for nanoresonators initially well above their ground states and can be utilized for teleportation of states from an atomic ensemble to the mechanical system.
Single-photon optomechanics in the strong coupling regime
U. Akram,N. Kiesel,M. Aspelmeyer,G. J. Milburn
Physics , 2010, DOI: 10.1088/1367-2630/12/8/083030
Abstract: We give a theoretical description of a coherently driven opto-mechanical system with a single added photon. The photon source is modeled as a cavity which initially contains one photon and which is irreversibly coupled to the opto-mechanical system. We show that the probability for the additional photon to be emitted by the opto-mechanical cavity will exhibit oscillations under a Lorentzian envelope, when the driven interaction with the mechanical resonator is strong enough. Our scheme provides a feasible route towards quantum state transfer between optical photons and micromechanical resonators.
High-Resolution X-Ray Reflectivity Study of Thin Layered Pt-Electrodes for Integrated Ferroelectric Devices
M. Aspelmeyer,U. Klemradt,W. Hartner,H. Bachhofer,G. Schindler
Physics , 2000,
Abstract: The structural interface properties of layered Pt/Ti/SiO2/Si electrodes have been investigated using high-resolution specular and diffuse x-ray reflectivity under grazing angles. Currently this multilayer system represents a technological standard as bottom electrodes for ferroelectric thin film applications. For the electronic and ferroelectric properties of integrated devices, the film-electrode interface is of crucial importance. We focused on Pt-100nm/Ti-10nm/SiO2/Si electrodes prepared under annealing conditions as employed in industrial processing, prior to the deposition of ferroelectric films. The comparison between annealed and non-annealed electrodes clearly revealed strong interfacial effects due to interdiffusion and oxidation of Ti, especially at the Pt-Ti interface. Migration of Ti into the Pt-layer results in a clear shift of the critical angle due to enclosure of TiO(2-x) within the Pt-layer. The heterogeneous distribution of TiO(2-x) suggests a diffusion mechanism mainly along the Pt-grain boundaries. At the SiO2 interface a relatively weakly oxidized, remaining Ti-layer of 20 Angstroem could be found, which is most probably correlated with the remaining adhesion to the substrate.
Phase-noise induced limitations on cooling and coherent evolution in opto-mechanical systems
P. Rabl,C. Genes,K. Hammerer,M. Aspelmeyer
Physics , 2009, DOI: 10.1103/PhysRevA.80.063819
Abstract: We present a detailed theoretical discussion of the effects of ubiquitous laser noise on cooling and the coherent dynamics in opto-mechanical systems. Phase fluctuations of the driving laser induce modulations of the linearized opto-mechanical coupling as well as a fluctuating force on the mirror due to variations of the mean cavity intensity. We first evaluate the influence of both effects on cavity cooling and find that for a small laser linewidth the dominant heating mechanism arises from intensity fluctuations. The resulting limit on the final occupation number scales linearly with the cavity intensity both under weak and strong coupling conditions. For the strong coupling regime, we also determine the effect of phase noise on the coherent transfer of single excitations between the cavity and the mechanical resonator and obtain a similar conclusion. Our results show that conditions for optical ground state cooling and coherent operations are experimentally feasible and thus laser phase noise does pose a challenge but not a stringent limitation for opto-mechanical systems.
Creating and probing macroscoping entanglement with light
M. Paternostro,D. Vitali,S. Gigan,M. S. Kim,C. Brukner,J. Eisert,M. Aspelmeyer
Physics , 2006, DOI: 10.1103/PhysRevLett.99.250401
Abstract: We describe a scheme showing signatures of macroscopic optomechanical entanglement generated by radiation pressure in a cavity system with a massive movable mirror. The system we consider reveals genuine multipartite entanglement. We highlight the way the entanglement involving the inaccessible massive object is unravelled, in our scheme, by means of field-field quantum correlations.
Cavity Optomechanics of Levitated Nano-Dumbbells: Non-Equilibrium Phases and Self-Assembly
W. Lechner,S. J. M. Habraken,N. Kiesel,M. Aspelmeyer,P. Zoller
Physics , 2012, DOI: 10.1103/PhysRevLett.110.143604
Abstract: Levitated nanospheres in optical cavities open a novel route to study many-body systems out of solution and highly isolated from the environment. We show that properly tuned optical parameters allow for the study of the non-equilibrium dynamics of composite nano-particles with non-isotropic optical friction. We find friction induced ordering and nematic transitions with non-equilibrium analogs to liquid crystal phases for ensembles of dimers.
Observation of non-Markovian micro-mechanical Brownian motion
S. Groeblacher,A. Trubarov,N. Prigge,G. D. Cole,M. Aspelmeyer,J. Eisert
Physics , 2013,
Abstract: All physical systems are to some extent open and interacting with their environment. This insight, basic as it may seem, gives rise to the necessity of protecting quantum systems from decoherence in quantum technologies and is at the heart of the emergence of classical properties in quantum physics. The precise decoherence mechanisms, however, are often unknown for a given system. In this work, we make use of an opto-mechanical resonator to obtain key information about spectral densities of its condensed-matter heat bath. In sharp contrast to what is commonly assumed in high-temperature quantum Brownian motion describing the dynamics of the mechanical degree of freedom, based on a statistical analysis of the emitted light, it is shown that this spectral density is highly non-Ohmic, reflected by non-Markovian dynamics, which we quantify. We conclude by elaborating on further applications of opto-mechanical systems in open system identification.
Pulsed quantum optomechanics
M. R. Vanner,I. Pikovski,G. D. Cole,M. S. Kim,C. Brukner,K. Hammerer,G. J. Milburn,M. Aspelmeyer
Physics , 2010, DOI: 10.1073/pnas.1105098108
Abstract: Studying mechanical resonators via radiation pressure offers a rich avenue for the exploration of quantum mechanical behavior in a macroscopic regime. However, quantum state preparation and especially quantum state reconstruction of mechanical oscillators remains a significant challenge. Here we propose a scheme to realize quantum state tomography, squeezing and state purification of a mechanical resonator using short optical pulses. The scheme presented allows observation of mechanical quantum features despite preparation from a thermal state and is shown to be experimentally feasible using optical microcavities. Our framework thus provides a promising means to explore the quantum nature of massive mechanical oscillators and can be applied to other systems such as trapped ions.
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