1,721,037 research outputs found
ENHANCEMENT OF SPONTANEOUS AND STIMULATED-EMISSION IN THE MICROLASER BY STANDING-WAVE RESONANT EXCITATION
No full textBy a new method of momentum-space excitation an increase of the spontaneous emission rate and a large reduction of the microlaser threshold are obtained. The method is demonstrated by an optically excited microlaser filled with europium atoms. The method is general and may be extended to active cavities with any dimension and geometry. Our results on spontaneous emission are interpreted as a demonstration of the first-order interference of the vacuum field
Multiparty multilevel energy-time entanglement
No full textFranson-like setups are inadequate for multiparty Bell experiments with energy-time entanglement because postselected events can depend on the local settings, and local models can exploit this feature to reproduce the quantum predictions, even in the case of ideal devices. We extend a previously introduced interferometric scheme [ A. Cabello et al. Phys. Rev. Lett. 102 040401 (2009)] to solve this problem in the N-qubit and N-quNit cases. In addition, the proposed setups allow us to prepare and test N-qubit Greenberger-Horne-Zeilinger and (∑i=1N|i...i〉)/√N energy-time entangled states
All-versus-nothing nonlocality test of quantum mechanics by two-photon hyperentanglement
No full textWe report the experimental realization and the characterization of polarization and momentum hyperentangled two-photon states, generated by a new parametric source of correlated photon pairs. By adoption of these states an "all-versus-nothing" test of quantum mechanics was performed. The two-photon hyperentangled states are expected to find at an increasing rate a widespread application in state engineering and quantum information
Polarization-momentum hyperentangled states: Realization and characterization
No full textWe present an experimental method to engineer polarization-momentum hyperentangled two-photon states, using linear optics and a single type-I nonlinear crystal. These states have been completely characterized and their nonlocal behavior has been verified by an "all versus nothing" test of local realism, which represents a generalization of the Greenberger-Horne-Zeilinger (GHZ) to the case of two entangled particles and two observers. The manipulation of these states may represent a useful control in quantum state engineering and Bell state measurements and, more in general, in quantum information applications
Hyperentangled photon states on a chip
No full textIn order to achieve an optimal scalability, stability and compactness of complex quantum optical schemes based on a large number of elements, waveguide technology is of fundamental importance. Lately this technique has been implemented with experimental success with the introduction in the quantum domain of photonic integrated circuits built in various platforms and materials [1
SPONTANEOUS EMISSION IN THE OPTICAL MICROSCOPIC CAVITY
No full textThe quantum theory of the spontaneous emission (SpE) from an active microscopic cavity (microcavity) is given with emphasis on mirror separations of the order of the optical wavelength. The theory is based on a complete set of orthonormal-mode functions that include both transverse polarizations and span the infinite three dimensional space that pervades and surrounds the microcavity. SpE rates for different active-dipole orientations and cavity configurations are calculated. The SpE pulse shape detected outside the cavity is shown to be generally nonexponential. A detailed computer simulation of the process is presented on the basis of the given theory in the perspective of our experiment, for a cavity terminated by mirrors bearing either metal- or semiconductor-multilayered coatings. We then report an extensive experimental verification of the theory by adopting an Eu-dibenzoylmethane complex as active medium with SpE from the 5D0-7F2 line at λ=6111 Å, under coherent uv excitation at λp=3547 Å. The results show evidence of ‘‘SpE inhibition’’ and ‘‘enhancement,’’ of nonexponential decay of SpE signals, and of competition with superradiance and stimulated emission. Finally we report the results of an experimental test of the algorithm adopted in all computer calculations of the optical parameters of the multilayered structures used for cavity confinement
Experimental realization of the Deutsch-Jozsa algorithm with a six-qubit cluster state
No full textWe describe an experimental realization of the Deutsch-Jozsa quantum algorithm to evaluate the properties of a two-bit Boolean function in the framework of one-way quantum computation. For this purpose, a two-photon six-qubit cluster state was engineered. Its peculiar topological structure is the basis of the original measurement pattern allowing the algorithm realization. The good agreement of the experimental results with the theoretical predictions, obtained at ~1 kHz success rate, demonstrates the correct implementation of the algorithm
Experimental achievement of the entanglement-assisted capacity for the depolarizing channel
No full textWe experimentally demonstrate the achievement of the entanglement-assisted capacity for classical information transmission over a depolarizing channel. The implementation is based on the generation and local manipulation of two-qubit Bell states, which are finally measured at the receiver by realizing projective measurements in the Bell basis. The depolarizing channel is realized by introducing quantum noise in a controlled way on one of the two qubits. This work represents an investigation into the amount of information that can be shared in the presence of noise. DOI: 10.1103/PhysRevA.87.02233
AN INTEGRATED OPTICS LOGIC GATE FOR POLARIZATION- ENCODED QUANTUM QUBITS AND A METHOD FOR THE PRODUCTION AND USE THEREOF
No full text
- …
