1,720,991 research outputs found
Cavity mode frequencies and strong optomechanical coupling in two-membrane cavity optomechanics
Full text linkWe study the cavity mode frequencies of a Fabry–Pérot cavity containing two vibrating dielectric membranes. We derive the equations for the mode resonances and provide approximate analytical solutions for them as a function of the membrane positions, which act as an excellent approximation when the relative and center-of-mass position of the two membranes are much smaller than the cavity length. With these analytical solutions, one finds that extremely large optomechanical coupling of the membrane relative motion can be achieved in the limit of highly reflective membranes when the two membranes are placed very close to a resonance of the inner cavity formed by them. We also study the cavity finesse of the system and verify that, under the conditions of large coupling, it is not appreciably affected by the presence of the two membranes. The achievable large values of the ratio between the optomechanical coupling and the cavity decay rate, g/k, make this two-membrane system the simplest promising platform for implementing cavity optomechanics in the strong coupling regime
Signatures of strong interactions in Rydberg systems
No full textStrong interactions between Rydberg excitations in cold gases give rise to strong correlations within these samples. Here we present a series of techniques that allow to visualize such correlations either directly, by varying the degree of interaction between the excitations, or indirectly, through the analysis of the full counting statistics (FCS) of the excitation events. Combining the information obtained by both methods provides a more complete characterization of the system, and allows the study of the correlations emerging in the system as a consequence of the strongly interacting nature of Rydberg excitations. © 2016, EDP Sciences and Springer
Rydberg excitation in Bose-Einstein Condensates and optical lattices”, International Workshop on Ultracold Rydberg Physics
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Quantum driving of a two level system: Quantum speed limit and superadiabatic protocols - An experimental investigation
No full textA fundamental requirement in quantum information processing and in many other areas of science is the capability of precisely controlling a quantum system by preparing a quantum state with the highest fidelity and/or in the fastest possible way. Here we present an experimental investigation of a two level system, characterized by a time-dependent Landau-Zener Hamiltonian, aiming to test general and optimal high-fidelity control protocols. The experiment is based on a Bose-Einstein condensate (BEC) loaded into an optical lattice, then accelerated, which provides a high degree of control over the experimental parameters. We implement generalized Landau-Zener sweeps, comparing them with the well-known linear Landau-Zener sweep. We drive the system from an initial state to a final state with fidelity close to unity in the shortest possible time (quantum brachistochrone), thus reaching the ultimate speed limit imposed by quantum mechanics. On the opposite extreme of the quantum control spectrum, the aim is not to minimize the total transition time but to maximize the adiabaticity during the time-evolution, the system being constrained to the adiabatic ground state at any time. We implement such transitionless superadiabatic protocols by an appropriate transformation of the Hamiltonian parameters. This transformation is general and independent of the physical system
Generation and detection of large and robust entanglement between two different mechanical resonators in cavity optomechanics
Full text linkWe investigate a general scheme for generating, either dynamically or in the steady state, continuous variable entanglement between two mechanical resonators with different frequencies. We employ an optomechanical system in which a single optical cavity mode driven by a suitably chosen two-tone field is coupled to the two resonators. Significantly large mechanical entanglement can be achieved, which is extremely robust with respect to temperature
Measurement of the spin-forbidden decay rate (3s3d)1D2→(3s3p)P32,1 in M24g
No full textWe have measured the spin-forbidden decay rate from
(3s3d)D-1(2)->(3s3p)P-3(2,1) in Mg-24 atoms trapped in a magneto-optical
trap. The total decay rate, summing up both exit channels (3s3p)P-3(1)
and (3s3p)P-3(2), yields 196 +/- 10 s(-1) in excellent agreement with
resent relativistic many-body calculations of Porsev {[}Phys. Rev. A 64,
012508 (2001)]. The characterization of this decay channel is important
as it may limit the performance of quantum optics experiments carried
out with this ladder system as well as two-photon cooling experiments
currently explored in several groups
Dipole blockade and counting statistics in ultra-cold and Bose condensed Rydberg samples
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