1,721,278 research outputs found
Integrated photonic quantum circuits for polarization qubits
No full textQuantum information is a research field with origins in the late 1980s and early 1990s, resulting from the merging of classical information and quantum physics. The main goal of this discipline is to understand the quantum nature of information and learn how to formulate, manipulate, and process it by using physical systems that operate on quantum mechanical principles. The development of such technologies will open up completely new schemes of information transfer and processing, enable new forms of communication, and in general enhance the power of computers
Quantum simulation with advanced integrated photonics
No full textState-of–the-art laser-writing technology allows the creation of 3D photonic arrays for manipulating quantum photon states
Insight on future quantum networks
No full textIn the past few years, significant improvements have been achieved in quantum communication. To extend the communication range, however, a new technology based on quantum memories needs to be developed
Colloquium: Multiparticle quantum superpositions and the quantum-to-classical transition
No full textThis work reports on an extended research endeavor focused on the theoretical and experimental realization of a macroscopic quantum superposition (MQS) made up of photons. This intriguing, fundamental quantum condition is at the core of a famous argument conceived by Schrodinger in 1935. The main experimental challenge to the actual realization of this object resides generally in unavoidable and uncontrolled interactions with the environment, i.e., "decoherence," leading to the cancellation of any evidence of the quantum features associated with the macroscopic system. The present scheme is based on a nonlinear process, "quantum-injected optical parametric amplification," which, by a linearized cloning process maps the quantum coherence of a single-particle state, i.e., a microqubit, onto a macroqubit consisting of a large number M of photons in quantum superposition. Since the adopted scheme was found resilient to decoherence, a MQS demonstration was carried out experimentally at room temperature with M >= 10(4). The result led to an extended study of quantum cloning, quantum amplification, and quantum decoherence. The related theory is outlined and several experiments are reviewed, such as the test of the "no-signaling theorem" and the dynamical interaction of the photon MQS with a Bose-Einstein condensate. In addition, the consideration of the microqubit-macroqubit entanglement regime is extended to macroqubit-macroqubit conditions. The MQS interference patterns for large M are revealed in the experiment and bipartite microqubit-macroqubit entanglement was also demonstrated for a limited number of generated particles: M less than or similar to 12. Finally, the perspectives opened by this new method for further studies on quantum foundations and quantum measurement are considered. DOI: 10.1103/RevModPhys.84.176
Implementation of optimal phase-covariant cloning machines
No full textThe optimal phase-covariant quantum cloning machine (PQCM) broadcasts the information associated to an input qubit into a multiqubit system, exploiting a partial a priori knowledge of the input state. This additional a priori information leads to a higher fidelity than for the universal cloning. The present article first analyzes different innovative schemes to implement the 1 -> 3 PQCM. The method is then generalized to any 1 -> M machine for an odd value of M by a theoretical approach based on the general angular momentum formalism. Finally different experimental schemes based either on linear or nonlinear methods and valid for single photon polarization encoded qubits are discussed
Entanglement, Einstein Podolsky Rosen correlations and Schrodinger cat state generation by quantum-injected optical parametric amplification
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