Quantum Entanglement

A hybrid stochastic hierarchy equations of motion approach to treat the low temperature dynamics of non-Markovian open quantum systems

Jeremy M. Moix and Jianshu Cao
The hierarchical equations of motion technique has found widespread success as a tool to generate the numerically exact dynamics of non-Markovian open quantum systems. However, its application to low temperature environments remains a serious challenge due to the need for a deep hierarchy that arise ... [J. Chem. Phys. 139, 134106 (2013)] published Wed Oct 2, 2013.

Experimental observation of one-dimensional quantum holographic imaging

Xin-Bing Song, De-Qin Xu, Hai-Bo Wang, Jun Xiong, Xiangdong Zhang et al.
We report the experimental observation of quantum holographic imaging of one-dimensional object with entangled photon pairs, generated in a spontaneous parametric down-conversion process. The signal photons play both roles of object wave and reference wave in holography but are recorded by a point d ... [Appl. Phys. Lett. 103, 131111 (2013)] published Fri Sep 27, 2013.

How many invariant polynomials are needed to decide local unitary equivalence of qubit states?

Tomasz Maciazek, Michal Oszmaniec, and Adam Sawicki
Given L-qubit states with the fixed spectra of reduced one-qubit density matrices, we find a formula for the minimal number of invariant polynomials needed for solving local unitary (LU) equivalence problem, that is, problem of deciding if two states can be connected by local unitary operations. Int ... [J. Math. Phys. 54, 092201 (2013)] published Tue Sep 3, 2013.

Stabilizer information inequalities from phase space distributions

David Gross and Michael Walter
The Shannon entropy of a collection of random variables is subject to a number of constraints, the best-known examples being monotonicity and strong subadditivity. It remains an open question to decide which of these laws of information theory are also respected by the von Neumann entropy of many-bo ... [J. Math. Phys. 54, 082201 (2013)] published Wed Aug 28, 2013.

A new quantum data processing inequality

Salman Beigi
Quantum data processing inequality bounds the set of bipartite states that can be generated by two far apart parties under local operations; having access to a bipartite state as a resource, two parties cannot locally transform it to another bipartite state with a mutual information greater than tha ... [J. Math. Phys. 54, 082202 (2013)] published Mon Aug 26, 2013.

The complete Heyting algebra of subsystems and contextuality

A. Vourdas
The finite set of subsystems of a finite quantum system with variables in [openface Z](n), is studied as a Heyting algebra. The physical meaning of the logical connectives is discussed. It is shown that disjunction of subsystems is more general concept than superposition. Consequently, the quantum p ... [J. Math. Phys. 54, 082105 (2013)] published Mon Aug 19, 2013.

Entangled phase diagram of the Kugel-Khomskii model

Wojciech Brzezicki
We investigate the zero-temperature phase diagrams of the three-dimensional Kugel-Khomskii (d) model, relevant for KCuF using cluster mean-field approach. This diagram includes both ordinary long-range ordered magnetic and orbital phases together with ones exhibiting exotic entangled spin-orbital or ... [AIP Conf. Proc. 1550, 248 (2013)] published Wed Aug 14, 2013.

A qubit coupled with confined phonons: The interplay between true and fake decoherence

Vincent Pouthier
The decoherence of a qubit coupled with the phonons of a finite-size lattice is investigated. The confined phonons no longer behave as a reservoir. They remain sensitive to the qubit so that the origin of the decoherence is twofold. First, a qubit-phonon entanglement yields an incomplete true decohe ... [J. Chem. Phys. 139, 054103 (2013)] published Thu Aug 1, 2013.

Entanglement dynamics of two qubits coupled individually to Ohmic baths

Liwei Duan, Hui Wang, Qing-Hu Chen, and Yang Zhao
Developed originally for the Holstein polaron, the Davydov D ansatz is an efficient, yet extremely accurate trial state for time-dependent variation of the spin-boson model [N. Wu, L. Duan, X. Li, and Y. Zhao, J. Chem. Phys. 138, 084111 (2013)]. In this work, the Dirac-Frenkel time-dependent variati ... [J. Chem. Phys. 139, 044115 (2013)] published Fri Jul 26, 2013.

Exclusivity structures and graph representatives of local complementation orbits

Adan Cabello, Matthew G. Parker, Giannicola Scarpa, and Simone Severini
We describe a construction that maps any connected graph G on three or more vertices into a larger graph, H(G), whose independence number is strictly smaller than its Lovasz number which is equal to its fractional packing number. The vertices of H(G) represent all possible events consistent with the ... [J. Math. Phys. 54, 072202 (2013)] published Wed Jul 17, 2013.

Quantum illumination

Stephen G. Benka
Abstract not available. [Phys. Today 66, 18 (2013)] published Fri Jun 28, 2013.

Direct observation of time reversal violation

J. Bernabeu
A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this s ... [AIP Conf. Proc. 1540, 55 (2013)] published Wed Jun 12, 2013.

Compressive object tracking using entangled photons

Omar S. Magana-Loaiza, Gregory A. Howland, Mehul Malik, John C. Howell, and Robert W. Boyd
We present a compressive sensing protocol that tracks a moving object by removing static components from a scene. The implementation is carried out on a ghost imaging scheme to minimize both the number of photons and the number of measurements required to form a quantum image of the tracked object. ... [Appl. Phys. Lett. 102, 231104 (2013)] published Mon Jun 10, 2013.

A novel construction of complex-valued Gaussian processes with arbitrary spectral densities and its application to excitation energy transfer

Xin Chen, Jianshu Cao, and Robert J. Silbey
The recent experimental discoveries about excitation energy transfer (EET) in light harvesting antenna (LHA) attract a lot of interest. As an open non-equilibrium quantum system, the EET demands more rigorous theoretical framework to understand the interaction between system and environment and ther ... [J. Chem. Phys. 138, 224104 (2013)] published Mon Jun 10, 2013.

Non-Markovianity during the quantum Zeno effect

A. Thilagam
We examine the Zeno and anti-Zeno effects in the context of non-Markovian dynamics in entangled spin-boson systems in contact with noninteracting reservoirs. We identify enhanced non-Markovian signatures in specific two-qubit partitions of a Bell-like initial state, with results showing that the int ... [J. Chem. Phys. 138, 175102 (2013)] published Tue May 7, 2013.

An area law for the bipartite entanglement of disordered oscillator systems

Bruno Nachtergaele, Robert Sims, and Gunter Stolz
We prove an upper bound proportional to the surface area for the bipartite entanglement of the ground state and thermal states of harmonic oscillator systems with disorder, as measured by the logarithmic negativity. Our assumptions are satisfied for some standard models that are almost surely gaples ... [J. Math. Phys. 54, 042110 (2013)] published Wed Apr 24, 2013.

Functional Wigner representation of quantum dynamics of Bose-Einstein condensate

B. Opanchuk and P. D. Drummond
We develop a method of simulating the full quantum field dynamics of multi-mode multi-component Bose-Einstein condensates in a trap. We use the truncated Wigner representation to obtain a probabilistic theory that can be sampled. This method produces c-number stochastic equations which may be solved ... [J. Math. Phys. 54, 042107 (2013)] published Mon Apr 22, 2013.

Quantum entanglement based on surface phonon polaritons in condensed matter systems

Yang Ming, Zi-jian Wu, Ai-hong Tan, Xi-kui Hu, Fei Xu et al.
Surface phonon polariton (SPhP) is a special propagation mode in condensed matter systems. We present an investigation on the entanglement of SPhP modes. The entangled SPhP pairs are generated through launching entangled photons onto the grating coupling systems. The interaction Hamiltonian for the ... [AIP Advances 3, 042122 (2013)] published Thu Apr 18, 2013.

Quantum network theory of computing with respect to entangled flux qubits and external perturbation

C. A. Cain and C. H. Wu
In this work, we attempt to show the differences between traditional qubit-based spintronic methodology for quantum computation and the possible ballistic quantum network implementations. Flux qubits can be considered topologically similar to the persistent currents possessed as the angular momentum ... [J. Appl. Phys. 113, 154309 (2013)] published Wed Apr 17, 2013.

Universal quantum state merging

I. Bjelakovic, H. Boche, and G. Janssen
We determine the optimal entanglement rate of quantum state merging when assuming that the state is unknown except for its membership in a certain set of states. We find that merging is possible at the lowest rate allowed by the individual states. Additionally, we establish a lower bound for the cla ... [J. Math. Phys. 54, 032204 (2013)] published Tue Mar 19, 2013.

Entanglement in a multiverse with no common space-time

S. J. Robles-Perez
Inter-universal entanglement may even exist in a multiverse in which there is no common space-time among the universes. In particular, the entanglement between the expanding and contracting branches of the universe might have observable consequences in the dynamical and thermodynamical properties of ... [AIP Conf. Proc. 1514, 31 (2013)] published Fri Feb 22, 2013.