We perform a time-delay analysis of the strong field ionization of atomic hydrogen in the tunneling regime. We obtain values for the time delay by solving the time-dependent Schrödinger equation, and use these values as parameters to define the corresponding classical trajectories. We demonstrate th...

[Phys. Rev. A 85, 021401] Published Fri Feb 10, 2012

We theoretically analyze inverse radio-frequency (rf) spectroscopy experiments in two-component Fermi gases. We consider a small number of impurity atoms interacting strongly with a bath of majority atoms. In two-dimensional geometries we find that the main features of the rf spectrum correspond to ...

[Phys. Rev. A 85, 021602] Published Tue Feb 07, 2012

Optomechanical cooling of levitated dielectric particles represents a promising new approach in the quest to cool small mechanical resonators toward their quantum ground state. We investigate two-mode cooling of levitated nanospheres in a self-trapping regime. We identify a structure of overlapping,...

[Phys. Rev. A 85, 021802] Published Fri Feb 03, 2012

We study phase transitions and hysteresis in a system of dipolar bosons loaded into triangular optical lattices at zero temperature. We find that the quantum melting transition from supersolid to superfluid phase is first order, in contrast with the previous report. We also find that due to strong q...

[Phys. Rev. A 85, 021601] Published Fri Feb 03, 2012

Selective production of the doubly excited state in 464 MeV/u He-like Ar¹⁶⁺ ions was accomplished using three-dimensional resonant coherent excitation in a thin foil of silicon crystal. Through a coherent interaction with the periodic crystal field, the Ar¹⁶⁺ ions were resonantly excited sequentiall...

[Phys. Rev. A 85, 020701] Published Fri Feb 03, 2012

We theoretically demonstrate the possibility of using nanomechanical systems as single-photon routers. We show how electromagnetically induced transparency in cavity optomechanical systems can be used to produce a switch for a probe field in a single-photon Fock state using very low pumping powers o...

[Phys. Rev. A 85, 021801] Published Thu Feb 02, 2012

We establish the optimal quantum teleportation protocol for the realistic scenario where both the input state and quantum channel are afflicted by noise. By taking these effects into account, higher fidelities are achieved. The optimality of the proposed protocol prevails even when restricted to a r...

[Phys. Rev. A 85, 020301] Published Wed Feb 01, 2012

We show that two qubits, initially in a fully classical state, can develop significant quantum correlations as measured by the quantum discord (QD) under the action of a local memoryless noise (specifically we consider the case of a Markovian amplitude-damping channel). This is analytically proven a...

[Phys. Rev. A 85, 010102] Published Mon Jan 30, 2012

We discuss the role of an external phase reference in quantum interferometry. We point out inconsistencies in the literature with regard to the use of the quantum Fisher information (QFI) in phase estimation interferometric schemes. We discuss the interferometric schemes with and without an external...

[Phys. Rev. A 85, 011801] Published Fri Jan 27, 2012

We discuss the evolution from BCS to Bose-Einstein condensate (BEC) superfluids in the presence of spin-orbit coupling for a balanced mixture of ultracold fermions. The dependence of several thermodynamic properties, such as chemical potential, order parameter, pressure, entropy, isothermal compress...

[Phys. Rev. A 85, 011606] Published Fri Jan 27, 2012

We propose to apply the notion of the Schmidt number in order to show that a quantum memory or gate process is capable of maintaining a genuine multilevel quantum coherence. We present a simple criterion in terms of an average gate fidelity with respect to the input states of two mutually unbiased b...

[Phys. Rev. A 85, 010305] Published Thu Jan 26, 2012

Recently, Li et al. [ Phys. Rev. Lett. 107 060501 (2011)] have demonstrated that topologically protected measurement-based quantum computation can be implemented on the thermal state of a nearest-neighbor two-body Hamiltonian with spin-2 and spin-3/2 particles provided that the temperature is small...

[Phys. Rev. A 85, 010304] Published Mon Jan 23, 2012

We analyze the formation of the low-energy structure (LES) in above-threshold ionization spectra in strong-field ionization by midinfrared laser pulses by using both quasiclassical and quantum approaches. We show this structure to be largely classical in origin, resulting from a two-dimensional focu...

[Phys. Rev. A 85, 011403] Published Fri Jan 20, 2012

Recent experiments have demonstrated single-site resolved observation of cold atoms in optical lattices. Thus, in the future it may be possible to take repeated snapshots of an interacting quantum many-body system during the course of its evolution. Here we address the impact of the resulting quantu...

[Phys. Rev. A 85, 011605] Published Thu Jan 12, 2012

We present a theoretical quasiclassical treatment of the formation, during Coulomb explosion, of highly excited neutral H atoms (H^*) for strongly driven H₂. This process, where after the laser field is turned off, one electron escapes to the continuum while the other occupies a Rydberg state, was re...

[Phys. Rev. A 85, 011402] Published Wed Jan 11, 2012

Using analytical and numerical methods, it is shown that the momentum distribution of a matter wave packet launched in a random potential exhibits a pronounced coherent backscattering (CBS) peak. By analyzing the momentum distribution, key transport times can be directly measured. The CBS peak can b...

[Phys. Rev. A 85, 011604] Published Tue Jan 10, 2012

Casimir forces between surfaces immersed in bromobenzene have recently been measured by Munday et al. [ Nature (London) 454 07610 (2009)]. Attractive Casimir forces were found between gold surfaces. The forces were repulsive between gold and silica surfaces. We show the repulsion is due to retardat...

[Phys. Rev. A 85, 010701] Published Tue Jan 10, 2012

Bellman's optimality principle has been of enormous importance in the development of whole branches of applied mathematics, computer science, optimal control theory, economics, decision making, and classical physics. Examples are numerous: dynamic programming, Markov chains, stochastic dynamics, cal...

[Phys. Rev. A 85, 010303] Published Mon Jan 09, 2012

Multimode Gaussian quantum light, which includes multimode squeezed and multipartite quadrature entangled light, is a very general and powerful quantum resource with promising applications in quantum information processing and metrology. In this paper, we determine the ultimate sensitivity in the es...

[Phys. Rev. A 85, 010101] Published Fri Jan 06, 2012

We show that a Bose-Hubbard model extended with pair-correlated hopping has exact eigenstates, quantum lattice compactons, with complete single-site localization. These appear at parameter values where the one-particle tunneling is exactly canceled by nonlocal pair correlations, and correspond in a ...

[Phys. Rev. A 85, 011603] Published Thu Jan 05, 2012

We derive the equation of state of bosons in an optical lattice in the framework of the Bose-Hubbard model. Near the density-driven Mott transition, the expression of the pressure P(μ,T) versus chemical potential and temperature is similar to that of a dilute Bose gas but with renormalized mass m^* a...

[Phys. Rev. A 85, 011602] Published Wed Jan 04, 2012

We introduce a scheme for perfect state transfer in regular two- and three-dimensional structures. The interactions on the lattices are of the XX spin type with uniform couplings. In two dimensions, the structure is a hexagonal lattice, and in three dimensions, it consists of hexagonal planes joined...

[Phys. Rev. A 85, 010302] Published Wed Jan 04, 2012

We study the phase diagram for spin-2 bosons loaded in a one-dimensional optical lattice. By using the non-Abelian density matrix renormalization group (DMRG) method we identify three possible phases: ferromagnetic, dimerized, and trimerized phases. We sketch the phase boundaries based on DMRG. We i...

[Phys. Rev. A 85, 011601] Published Tue Jan 03, 2012

We show that coherence between two excited rovibrational states belonging to the same molecular electronic configuration arises quite naturally due to their interaction with electromagnetic vacuum. For initial preparation of a molecule in the desired rovibrational states, we propose to employ the me...

[Phys. Rev. A 85, 011401] Published Tue Jan 03, 2012

We analyze the security and feasibility of a protocol for quantum key distribution (QKD) in a context where only one of the two parties trusts his measurement apparatus. This scenario lies naturally between standard QKD, where both parties trust their measurement apparatuses, and device-independent ...

[Phys. Rev. A 85, 010301] Published Tue Jan 03, 2012

A process of preparation, transmission, and subsequent projective measurement of a qubit can be simulated by a classical model with only two bits of communication and some amount of shared randomness. However, to the best of our knowledge, no model for n qubits with a finite amount of classical comm...

[Phys. Rev. A 84, 060303] Published Thu Dec 29, 2011

Transitions between quantum states by photon absorption or emission are intimately related to the symmetries of the system which lead to selection rules and the formation of dark states. In a circuit quantum electrodynamics setup, in which two resonant superconducting qubits are coupled through an o...

[Phys. Rev. A 84, 061805] Published Wed Dec 28, 2011

We study the dynamical decoupling of multiqubit states from environment. For a system of m qubits, the nested Uhrig dynamical decoupling (NUDD) sequence can efficiently suppress generic decoherence induced by the system-environment interaction to order N using (N+1)^2m pulses. We prove that the NUDD ...

[Phys. Rev. A 84, 060302] Published Wed Dec 28, 2011

We have experimentally demonstrated high-resolution compressive ghost imaging at the single-photon level using entangled photons produced by a spontaneous parametric down-conversion source and using single-pixel detectors. For a given mean-squared error, the number of photons needed to reconstruct a...

[Phys. Rev. A 84, 061804] Published Tue Dec 27, 2011

Quantum control in high-order-harmonic generation is considered theoretically by using a spatial distribution of static electric fields along the propagation direction of the driving field. It is shown that the trajectories of the electrons during its acceleration by the laser field in the high-harm...

[Phys. Rev. A 84, 061803] Published Tue Dec 27, 2011