Measuring nonclassicality of single-mode systems

Abstract

Nonclassicality of a single-mode state can be quantified by the entanglement (potential) the state creates at the output of a beam splitter. Thus, beam splitter transformation can be utilized for obtaining single-mode nonclassicality conditions (quantifications) from two-mode entanglement criteria (measures). Here, (i) we employ this relation to quantify the single-mode nonclassicality (SMNc) of a nonlinear crystal field generating second harmonic signals. (ii) We also manage to witness the SMNc of superradiant emission, a non-Gaussian state, in a Dicke phase transition. Entanglement potential, at the beam splitter output, is obtained in terms of measurable single-mode quantities. Thus, presence of a beam splitter in an experiment is not necessary. Employing the beam splitter method, one can also utilize hybrid entanglement criteria as SMNc conditions working well in different classes of single-mode states. (iii) We also work on essentials of the entanglement-SMNc relation: one obtains the generalized squeezing condition ⟨â†â⟩ < |⟨â2⟩| as the SMNc condition when an optimized form of Duan–Giedke–Cirac–Zoller criterion [PRL 84, 2722] is used at the output of the beam splitter.

Lattice-plasmon effect on entanglement behavior in a plasmonic system

“…The correlation matrix elements must be calculated to investigate the two-mode entanglement influenced by the system's density matrix. 5,6 To calculate the expectation value, it is supposed that the initial state is jψ > ×j0 >. Working on the Heisenberg picture, for instance, the expectation value of hX 1 i is calculated as E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 7 ; 1 1 6 ; 5 3 1…”

“…In the same way as the calculation of hX 1 i, the correlation matrix elements are determined by computing hP 1 i, hX 2 i, hP 2 i, hX 2 1 i, hX 2 2 i, hP 2 1 i, hP 2 2 i, hX 1 :X 2 i, hP 1 :P 2 i, hX 1 :P 2 i, hP 1 :X 2 i and other parts to form the correlation matrix V 4×4 ¼ ½A; C; C T ; B with contributed elements as 5,6 E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 8 ; 1 1 6 ; 2 9 7…”

“… – 4 Entanglement is an essential quantum feature in many published works that involve the unique properties of non-local correlation of the entangled states 5 – 9 The entanglement phenomenon has been employed in different applications, such as high-resolution imaging systems, 10 quantum communication and illumination systems, 1 , 2 and quantum radar systems 11 . An entangled system comprises two or more subsystems with an overall state vector that cannot be completely decomposed into a product of the individual state vector of the subsystems.…”

Voltage-tunable integrated quantum entanglement device via nonlinear Fano resonances

“…Thus, one can either (i) use the two entangled light beams or (ii) create entanglement (on the right hand side) from the nonclassicality inherited in bout using an integrated beam-splitter [33]. Beyond the generation of nonclassicality [34,35], the most important thing our device can provide is the continuous tunability of the quantum nonclassicality (by several orders of magnitude) via an applied voltage.…”

“…FIG.3. Single-mode nonclassicality (NSMNc) of the output mode bout in units of log-neg[34,45]. The right-going output can be used to generate entanglement via a beam-splitter[42].…”