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We investigate ground state properties of spin-1 bosonic system trapped in

optical lattice with extended standard basis operator (SBO) method. For both

ferromagnetic ($U_2<0$) and antiferromagnetic ($U_2>0$) systems, we

analytically figure out the symmetry properties in Mott-insulator and

superfluid phases, which would provide a deeper insight into the MI-SF phase

transition process. Then by applying self-consistent approach to the method, we

include the effect of quantum and thermal fluctuations and derive the MI-SF

Communication over a noisy channel is often conducted in a setting in which

different input symbols to the channel incur a certain cost. For example, for

the additive white Gaussian noise channel, the cost associated with a real

number input symbol is the square of its magnitude. In such a setting, it is

often useful to know the maximum amount of information that can be reliably

transmitted per cost incurred. This is known as the capacity per unit cost. In

- Read more about Quantum Channel Capacities Per Unit Cost. (arXiv:1705.08878v1 [quant-ph])
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With the Lipkin-Meshkov-Glick (LMG) model as an illustration, we construct a

thermodynamic cycle composed of two isothermal processes and two isomagnetic

field processes and study the thermodynamic performance of this cycle

accompanied by the quantum phase transition (QPT). We find that for a finite

particle system working below the critical temperature, the efficiency of the

cycle is capable of approaching the Carnot limit when the external magnetic

field \lambda_{1} corresponding to one of the isomagnetic processes reaches the

- Read more about Quantum thermodynamic cycle with quantum phase transition. (arXiv:1705.08625v1 [quant-ph])
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We demonstrate a synchronized readout (SR) technique for spectrally selective

detection of oscillating magnetic fields with sub-millihertz resolution, using

coherent manipulation of solid state spins. The SR technique is implemented in

a sensitive magnetometer (~50 picotesla/Hz^(1/2)) based on nitrogen vacancy

(NV) centers in diamond, and used to detect nuclear magnetic resonance (NMR)

signals from liquid-state samples. We obtain NMR spectral resolution ~3 Hz,

We study the unidirectional amplification of optical probe fields in a

three-mode optomechanical system, where the mechanical resonator interacts with

two linearly-coupled optical cavities and the cavities are driven by strong

optical pump fields. An optical probe field is injected into one of the cavity

modes, and at the same time, it is applied to the mechanical mode after being

down-converted by the optical pump frequency. We show that the transmission of

This paper presents a new measure of entanglement which can be employed for

multipartite entangled systems. The classification of multipartite entangled

systems based on this measure is considered. Two approaches to applying this

measure to mixed quantum states are discussed.

We propose a bosonic Josephson junction (BJJ) in two nonlinear mechanical

resonator coupled through two-phonon exchange interaction induced by quadratic

optomechanical couplings. The nonlinear dynamic equations and effective

Hamiltonian are derived to describe behaviors of the BJJ. We show that the BJJ

can work in two different dynamical regimes: Josephson oscillation and

macroscopic self-trapping. The system can transfer from one regime to the other

one when the self-interaction and asymmetric parameters exceed their critical

In recent years, the study of heat to work conversion has been re-invigorated

by nanotechnology. Steady-state devices do this conversion without any

macroscopic moving parts, through steady-state flows of microscopic particles

such as electrons, photons, phonons, etc. This review aims to introduce some of

the theories used to describe these steady-state flows in a variety of

mesoscopic or nanoscale systems. These theories are introduced in the context

of idealized machines which convert heat into electrical power (heat-engines)

We consider two chains, each made of $N$ independent oscillators, immersed in

a common thermal bath and study the dynamics of their mutual quantum

correlations in the thermodynamic, large-$N$ limit. We show that dissipation

and noise due to the presence of the external environment are able to generate

collective quantum correlations between the two chains at the mesoscopic level.

The created collective quantum entanglement between the two many-body systems

We study the existence of the maximal quantum Fisher information matrix in

multi-parameter quantum estimation, which bounds the ultimate precision limit.

We show that when the maximal quantum Fisher information matrix exists, it can

be directly obtained from the underlying dynamics. Examples are then provided

to demonstrate the usefulness of the maximal quantum Fisher information matrix

by deriving various tradeoff relations in multi-parameter quantum estimation

and obtaining the bounds for the scalings of the precision limit.

- Read more about Maximal quantum Fisher information matrix. (arXiv:1705.08649v1 [quant-ph])
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