Motivated by recent experiments on toroidal Bose-Einstein condensates in all-optical traps with tunable weak links, we study the one-dimensional Bose-Hubbard model on a ring-shaped lattice with a small region of weak hopping integrals using quantum Monte Carlo simulations. Besides the usual Mott ins...

[Phys. Rev. A 87, 051607] Published Fri May 24, 2013

We report a state-independent experimental test of quantum contextuality of a single-photon qutrit. The experimental results demonstrate violations of an inequality originally formulated by Yu and Oh [ Phys. Rev. Lett. 108 030402 (2012)] and further optimized by Cabello et al. [ Phys. Rev. A 85 03...

[Phys. Rev. A 87, 052133] Published Fri May 24, 2013

An alternative formulation to the (generalized) Born rule is presented. It involves estimating an unknown model from a finite set of measurement operators on the state. An optimality principle is given that relates to achieving bounded solutions by regularizing the unknown parameters in the model. T...

[Phys. Rev. A 87, 052134] Published Fri May 24, 2013

In a recent paper [ S. M. Cohen Phys. Rev. A 84 052322 (2011)], we showed how to construct a protocol for implementing a bipartite, separable quantum measurement using only local operations on subsystems and classical communication between parties (LOCC) within any fixed number of rounds of communi...

[Phys. Rev. A 87, 052135] Published Fri May 24, 2013

We investigate how the entanglement characteristics of a non-Gaussian entangled state are increased or decreased by a local photon subtraction operation. The non-Gaussian entangled state is generated by injecting a single-mode non-Gaussian state and a vacuum state into a 50:50 beam splitter. We cons...

[Phys. Rev. A 87, 052321] Published Fri May 24, 2013

We discuss collapse and revival of Rabi oscillations in a system comprising a qubit and a “big spin” (made of N qubits, or spin-1/2 particles). We demonstrate a regime of behavior analogous to conventional collapse and revival for a qubit-field system, employing spin coherent states for the initial ...

[Phys. Rev. A 87, 052323] Published Fri May 24, 2013

We present detailed calculations for the Casimir force between a plane and a nanostructured surface at finite temperature in the framework of the scattering theory. We then study numerically the effect of finite temperature as a function of the grating parameters and the separation distance. We also...

[Phys. Rev. A 87, 052514] Published Fri May 24, 2013

We present an optimal protocol to implement a room-temperature Rydberg single-photon source within an experimental setup based on micro cells filled with thermal vapor. The optimization of a pulsed four wave mixing scheme allows us to double the effective Rydberg blockade radius as compared to a sim...

[Phys. Rev. A 87, 053412] Published Fri May 24, 2013

Quantum backflow is a classically forbidden effect consisting of a negative flux for states with negligible negative-momentum components. It has never been observed experimentally so far. We derive a general relation that connects backflow with a critical value of the particle density, paving the wa...

[Phys. Rev. A 87, 053618] Published Fri May 24, 2013

The strong demand for quantum memory, a key building block of quantum network, has inspired new methodologies and led to experimental progress for quantum storage. The use of quantum memory for spatial multimode or image storage could dramatically increase the channel bit rate. Furthermore, quantum ...

[Phys. Rev. A 87, 053830] Published Fri May 24, 2013

In this article, the processes of energy absorption and coherent transfer in a dimer are studied. The dimer includes two two-level pigments, donor and acceptor, where the donor is assumed to be excited by a control pulse in the time domain. We investigate the dynamics of probability that the accepto...

[Phys. Rev. A 87, 053831] Published Fri May 24, 2013

An analytical approach is used to describe the dispersion of phase resonances occurring between waveguide cavity modes in compound transmission gratings. The strongly enhanced evanescent fields associated with the phase resonances are used to derive an approximate closed-form equation for the disper...

[Phys. Rev. A 87, 053833] Published Fri May 24, 2013

We propose an interferometric method for the direct measurement of the moments of the transverse spatial variables of an optical field. The key elements are spatial light modulators, used to imprint a transverse phase on the field. We show that our measurement scheme can be used to measure the spati...

[Phys. Rev. A 87, 053834] Published Fri May 24, 2013

We theoretically propose a method to enhance Raman scattering by injecting a seeded light field which is correlated with the initially prepared atomic spin wave. Such a light-atom correlation leads to an interference in the Raman scattering. The interference is sensitive to the relative phase betwee...

[Phys. Rev. A 87, 053835] Published Fri May 24, 2013

Ground-state phase diagram of two-component Bose gases with Rashba spin-orbit coupling is determined via a variational approach. A phase in which the fully polarized condensate occupies zero momentum is identified. This zero-momentum phase competes with the spin density wave phase when interspecies ...

[Phys. Rev. A 87, 051606] Published Thu May 23, 2013

The framework of generalized probabilistic theories is a popular approach for studying the physical foundations of quantum theory. The standard framework assumes the no-restriction hypothesis, in which the state space of a physical theory determines the set of measurements. However, this assumption ...

[Phys. Rev. A 87, 052131] Published Thu May 23, 2013

We introduce a method to witness the quantumness of a system. The method relies on the fact that the anticommutator of two classical states is always positive. By contrast, we show that there is always a nonpositive anticommutator due to any two quantum states. We notice that interference depends on...

[Phys. Rev. A 87, 052132] Published Thu May 23, 2013

Laser light is widely used for communication and sensing applications, so the optimal discrimination of coherent states—the quantum states of light emitted by an ideal laser—has immense practical importance. Due to fundamental limits imposed by quantum mechanics, such discrimination has a finite min...

[Phys. Rev. A 87, 052320] Published Thu May 23, 2013

Multiphoton states can be produced in multiple parametric down-conversion (PDC) processes. The nonlinear crystal in such a case is pumped with high power. In theory, the more populated these states are, the deeper is the conflict with local realistic description. However, the interference contrast i...

[Phys. Rev. A 87, 053828] Published Thu May 23, 2013

We attempt to evaluate the applicability of the concept of the critical power for self-focusing, originally developed for intense quasi-continuous-wave (cw) beams, to the case of ultra-intense and ultrashort laser pulses propagating in air. Our results show that, unlike in the cw case, no particular...

[Phys. Rev. A 87, 053829] Published Thu May 23, 2013

We present a formalism which allows one to define probabilities for expressions that involve properties at different times for classical and quantum systems and we study its lattice structure. The formalism is based on the notion of time translation of properties. In the quantum case, the properties...

[Phys. Rev. A 87, 052128] Published Wed May 22, 2013

We investigate the conditions under which the trace distance between two different states of a given open system increases in time due to the interaction with an environment, therefore signaling non-Markovianity. We find that the finite-time difference in trace distance is bounded by two sharply def...

[Phys. Rev. A 87, 052129] Published Wed May 22, 2013

We present results of an experiment to probe for the electric dipole moment (EDM) of the electron using an Ω-doublet state in a polar molecule. If the molecule is both massive and has a large molecular-fixed frame dipole moment, then the Ω-doublet states have the potential to greatly increase the se...

[Phys. Rev. A 87, 052130] Published Wed May 22, 2013

We present a self-interaction-free time-dependent density-functional theory (TDDFT) for the treatment of double-ionization processes of many-electron systems. The method is based on the extension of the Krieger-Li-Iafrate (KLI) treatment of the optimized effective potential (OEP) theory and the inco...

[Phys. Rev. A 87, 052513] Published Wed May 22, 2013

We report calculations for the single- and multiphoton ionization of the H₂⁺ molecular ion irradiated by ultrashort elliptically polarized laser pulses for central photon energies ranging from close to the ionization threshold up to 300 eV. Using the fixed-nuclei approximation, the electronic respon...

[Phys. Rev. A 87, 053410] Published Wed May 22, 2013

Accurate knowledge of the intensity of focused ultrashort laser pulses is crucial to the correct interpretation of experimental results in strong-field physics. We have developed a technique to measure laser intensities approaching 10¹⁵ W/cm² with an accuracy of 1%. This accuracy is achieved by comp...

[Phys. Rev. A 87, 053411] Published Wed May 22, 2013

For a weakly interacting Bose gas rotating in a harmonic trap we relate the yrast states of small systems (that can be treated exactly) to the thermodynamic limit (derived within the mean-field approximation). For a few dozens of atoms, the yrast line shows distinct quasiperiodic oscillations with i...

[Phys. Rev. A 87, 053615] Published Wed May 22, 2013

By adopting a T-matrix-based method within the G₀G approximation for the pair susceptibility, we study the effects of the pairing fluctuation on the three-dimensional spin-orbit-coupled Fermi gases at finite temperature. The critical temperatures of the superfluid to normal phase transition are dete...

[Phys. Rev. A 87, 053616] Published Wed May 22, 2013

Multiple phases occurring in a Bose gas with finite-range interaction are investigated. In the vicinity of the onset of Bose-Einstein condensation (BEC), the chemical potential and the pressure show a van der Waals–like behavior indicating a first-order phase transition although there is no long-ran...

[Phys. Rev. A 87, 053617] Published Wed May 22, 2013

The time- and frequency-resolved nonlinear light scattering (NLS) signals from a time-evolving charge distribution of valence electrons prepared by impulsive x-ray pulses are calculated using a superoperator Green's function formalism. The signal consists of a coherent ∼N²-scaling difference-frequen...

[Phys. Rev. A 87, 053826] Published Wed May 22, 2013