Search results for "quantum entanglement"
showing 10 items of 320 documents
Standard forms and entanglement engineering of multimode Gaussian states under local operations
2007
We investigate the action of local unitary operations on multimode (pure or mixed) Gaussian states and single out the minimal number of locally invariant parametres which completely characterise the covariance matrix of such states. For pure Gaussian states, central resources for continuous-variable quantum information, we investigate separately the parametre reduction due to the additional constraint of global purity, and the one following by the local-unitary freedom. Counting arguments and insights from the phase-space Schmidt decomposition and in general from the framework of symplectic analysis, accompany our description of the standard form of pure n-mode Gaussian states. In particula…
Macroscopic entanglement in Josephson nanocircuits
2001
We propose a scheme to generate and detect entanglement between charge states in superconducting nanocircuits. We discuss different procedures to discriminate such entanglement from classical correlations. The case of maximally entangled states of two and three coupled Josephson junctions is discussed as example.
Removing phase ambiguity in fiber-based interferometers for coherent time-bin operations
2019
Time is a practical and robust degree of freedom for the encoding of quantum information. Qubits encoded in so-called 'time-bins', allowing a discrete superposition of two potential arrival times, have their entanglement preserved even over long propagation distances in standard fiber networks [1]. Time has also been used for the preparation of more complex quantum systems, such as hyper-entangled and cluster states [2]. These qualities put time-bin encoding at the center of applications ranging from quantum state preparation through to quantum communications and information processing. One of the hallmarks of the scheme is that a nonlinear element has to be pumped with phase-coherent doubl…
Universal multipartite d-level entanglement witnesses for realistic measurement settings
2019
Entanglement is an essential resource in quantum information science [1] and its presence in any quantum system can be experimentally detected through entanglement witness operators [2]. In particular, measuring a negative expectation value of a witness with high statistical confidence provides a necessary and sufficient condition to confirm the generation of a genuine multipartite [3] and/or d-level entangled state [4]. In recent years, the experimental generation of complex quantum states has intensified the need for witnesses that are capable of detecting such systems and are experimentally optimal at the same time. This means that the witness should require the least measurement effort …
Electric Field Generation and Control of Bipartite Quantum Entanglement between Electronic Spins in Mixed Valence Polyoxovanadate [GeV14O40]8–
2017
As part of the search for systems in which control of quantum entanglement can be achieved, here we consider the paramagnetic mixed valence polyoxometalate K2Na6[GeV14O40]·10H2O in which two electrons are delocalized over the 14 vanadium ions. Applying a homogeneous electric field can induce an antiferromagnetic coupling between the two delocalized electronic spins that behave independently in the absence of the field. On the basis of the proposed theoretical model, we show that the external field can be used to generate controllable quantum entanglement between the two electronic spins traveling over a vanadium network of mixed valence polyoxoanion [GeV14O40]8–. Within a simplified two-lev…
Visualizing pectin polymer-polymer entanglement produced by interfacial water movement.
2020
In this report, we investigated the physical conditions for creating pectin polymer-polymer (homopolymer) entanglement. The potential role of water movement in creating pectin entanglement was investigated by placing water droplets-equivalent to the water content of two gel phase films-between two glass phase films and compressing the films at variable probe velocities. Slow probe velocity (0.5 mm/sec) demonstrated no significant debonding. Corresponding videomicroscopy demonstrated an occasional water bridge, but no evidence of stranding or polymer entanglement. In contrast, fast probe velocity (5 mm/sec) resulted in 1) an increase in peak adhesion strength, 2) a progressive debonding curv…
Impact of many-body correlations on the dynamics of an ion-controlled bosonic Josephson junction
2016
We investigate an atomic ensemble of interacting bosons trapped in a symmetric double well potential in contact with a single tightly trapped ion which has been recently proposed [R. Gerritsma et al., Phys. Rev. Lett. 109, 080402 (2012)] as a source of entanglement between a Bose-Einstein condensate and an ion. Compared to the previous study, the present work aims at performing a detailed and accurate many-body analysis of such combined atomic quantum system by means of the ab-initio multi-configuration time-dependent Hartree method for bosons, which allows to take into account all correlations in the system. The analysis elucidates the importance of quantum correlations in the bosonic ense…
Entangled photons through thick scattering media: experiments and comparison with simulations of the biphoton wave function
2021
International audience; We report experimentally and numerically quantum correlations imaging through thick random media. We demonstrated that spatial correlations between twin photon are still detected but no in form of two-photon speckle-like patterns.
Kerr Combs and Telecommunications Components for the Generation and High-Dimensional Quantum Processing of d-Level Cluster States
2019
Large and complex optical quantum states are a key resource for fundamental science and applications such as quantum communications, information processing, and metrology. In this context, cluster states are a particularly important class because they enable the realization of universal quantum computers by means of the so-called ‘one-way’ scheme, where processing operations are performed through measurements on the state. While two-level (i.e. qubit) cluster states have been realized thus far, further boosting this computational resource by increasing the number of particles comes at the price of significantly reduced coherence time and detection rates, as well as increased sensitivity to …
Extension of the Concept of Intrinsic Viscosities to Arbitrary Polymer Concentration: From [η] via {η} to Intrinsic Bulkiness
2019
The capabilities of an alternative definition of intrinsic viscosities [η] published some years ago is being studied by means of comprehensive viscometric data reported in the early days of polymer science. It introduces the generalized intrinsic viscosity {η} as the specific hydrodynamic volume at arbitrary polymer concentration c. {η} quantifies the size of the flow unit and decreases monotonously for T ≫ Tg (glass transition temperature) as a function of c but passes a pronounced minimum as T approaches Tg. In the limit of the pure polymer melt, {η} becomes ; this newly introduced property is termed intrinsic bulkiness, by analogy to the intrinsic viscosity, and provides noncalorimetric …