Innovative method to investigate how the spatial correlation of the pump beam affects the purity of polarization entangled states

Cialdi, S.; Brivio, Davide; Tabacchini, Andrea; Kadhim, Ali Mohammed; Paris, Matteo G. A.

doi:10.1364/ol.37.003951

Cited by 4 publications

(5 citation statements)

References 14 publications

(21 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2, is based on PDC generated by two 1 mm adjacent type-I Beta-Barium Borate (BBO) crystals, oriented with their optical axes aligned in perpendicular planes and pumped by a 10 mW, 405 nm cw diode laser (Newport LQC405-40P). The two BBO crystals generate the signal and idler states with perpendicular polarization and the interference filter (F2) ensures a good spatial correlation between signal and idler [5,20,21]. We generate two channels 0 and 1 (corresponding to the momentum states |0 and |1 , respectively) with a double slit (DS) positioned along the idler path.…”

mentioning

confidence: 99%

Two-step procedure to discriminate discordant from classical correlated or factorized states

et al. 2014

Self Cite

View full text Add to dashboard Cite

We devise and experimentally realize a procedure capable to detect and distinguish quantum discord and classical correlations, as well the presence of factorized states in a joint system-environment setting. Our scheme builds on recent theoretical results showing how the distinguishability between two reduced states of a quantum system in a bipartite setting can convey important information about the correlations present in the bipartite state and the interaction between the subsystems. The two addressed subsystems are the polarization and spatial degrees of freedom of the signal beam generated by parametric downconversion, which are suitably prepared by the idler beam. Different global and local operations allow for the detection of different correlations by studying via state tomography the trace distance behavior between suitable polarization subsystem states.The study of a bipartite system is an ever present theme which has led to important advancements in the understanding of quantum mechanics, especially when the two parties cannot be put on an equal footing. The prototypical situation is a measurement interaction, in which the interest is all on the side of the system, calling for tools and ideas allowing for an ever improving description of such interactions [1]. The theory of open quantum systems has provided a natural extension of these efforts, in which the quantum features of the measurement apparatus are put in major evidence [2], while correlations between system and environment have received important attention only more recently, thanks to the consolidation of quantum information theory [3]. The latest theoretical developments as well as the refinement in the experimental techniques has led to a change of paradigm in facing the system-environment (SE) dynamics. The possibility has been envisaged of actually exploiting the open quantum system, supposed to be liable to a relatively easy and accurate experimental observation, as a quantum probe of features of the environment, typically to be considered as a complex system. Properties of the environment which might be unveiled by an observation on the system up to now include the detection of quantum phase transitions [4], as well as the assessment of correlations within the state of the environment [5]. These advancements have been based on the study in time of the distinguishability of different initial system states [6], which has proven to be a fruitful strategy in order to exploit a quantum system as probe of features of a bipartite dynamics [7][8][9][10][11][12][13].In this paper we improve this approach to devise a novel method for the determination of quantum correlations, which play a crucial role both in quantum information and in the development of quantum technologies. The approach is based on a two-step procedure, which relying on measurements on the system only allows to determine whether a given initial SE state actually contains quantum correlations, as quantified by quantum discord or, if this is not the case, decide whether it contai...

show abstract

mentioning

confidence: 99%

Two-step procedure to discriminate discordant from classical correlated or factorized states

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…A programmable one-dimensional spatial light modulator (SLM) is placed on the path of signal and idler in order to control the visibility of the generated states. The SLM provides the setup with great flexibility, allowing the experimenter to choose and set the visibility of generated states [28,29]. Eventually, photons are focused in two multimode fibers and sent to singlephoton counting modules (CC).…”

Section: A Experimental Generation Of Werner Statesmentioning

confidence: 99%

Assessing the significance of fidelity as a figure of merit in quantum state reconstruction of discrete and continuous-variable systems

et al. 2016

Self Cite

View full text Add to dashboard Cite

We experimentally address the significance of fidelity as a figure of merit in quantum state reconstruction of discrete (DV) and continuous variable (CV) quantum optical systems. In particular, we analyze the use of fidelity in quantum homodyne tomography of CV states and maximum-likelihood polarization tomography of DV ones, focussing attention on nonclassicality, entanglement and quantum discord as a function of fidelity to a target state. Our findings show that high values of fidelity, despite well quantifying geometrical proximity in the Hilbert space, may be obtained for states displaying opposite physical properties, e.g. quantum or semiclassical features. In particular, we analyze in details the quantum-to-classical transition for squeezed thermal states of a single-mode optical system and for Werner states of a two-photon polarization qubit system.

show abstract

“…Moreover, A(ω p ) is the spectral arXiv:1302.0205v2 [quant-ph] 11 Apr 2013 amplitude of the pump,F (∆k ⊥ ) is the Fourier transform of its spatial amplitude and the Sinc(∆k L/2) function arises due to the finite crystal size (L = 1mm) along the longitudinal direction. The two-crystal geometry implies that the polarization degrees of freedom of the two photons are entangled and it further introduces the phase term Φ(ω p , θ s , θ i ), which is due to the different optical paths followed by the couples of photons generated in the first and in the second crystal [27][28][29]. To first order this term reads Φ(ω p , θ s , θ i ) ≈ Φ 0 + ∆τ ω p + κθ s + ηθ i .…”

Section: The Physical System and The Experimental Apparatusmentioning

confidence: 99%

“…In fact, through the SLM we can impose an arbitrary polarization-and positiondependent phase shift to the two-photon state in Eq.(1). On the one hand, a linear phase Φ ≡ −Φ 0 − κθ s − ηθ i is set to offset the corresponding terms in the first-order expansion of Φ(ω p , θ s , θ i ) [27][28][29][30]. On the other hand, a further linear phase on both signal and idler beams emulates a time evolution of the two-photon state [31].…”

Section: The Physical System and The Experimental Apparatusmentioning

confidence: 99%

“…In ferent beam divergences exploited, together with a 10nmspectrum, in the preparation of the environmental state ρ 2 E (0). The divergence is enlarged by suitably setting a telescopic system of lenses, so that the FWHM ∆k of | F (∆k ⊥ )| 2 is increased, while the 220µm spot on the generating crystals is kept fixed [29]. The increase of the trace distance above its initial value grows with the angular correlations C in ρ 2 E (0).…”

Section: B Trace Distance As a Witness Of Initial Correlations In The...mentioning

confidence: 99%

See 1 more Smart Citation

Quantum probes to experimentally assess correlations in a composite system

et al. 2013

Self Cite

View full text Add to dashboard Cite

We suggest and demonstrate experimentally a strategy to obtain relevant information about a composite system by only performing measurements on a small and easily accessible part of it, which we call quantum probe. We show in particular how quantitative information about the angular correlations of couples of entangled photons generated by spontaneous parametric down conversion is accessed through the study of the trace distance between two polarization states evolved from different initial conditions. After estimating the optimal polarization states to be used as quantum probe, we provide a detailed analysis of the connection between the increase of the trace distance above its initial value and the amount of angular correlations.PACS numbers: 03.65. Yz,03.65.Ta,42.50.Dv The control of quantum systems plays a basic role in the experimental investigation of the predictions of quantum theory as well as in the development of quantum technologies for applications. Indeed, great attention has been recently payed to engineering the dynamics of quantum systems in order to properly generate, manipulate and exploit significant quantum features [1][2][3][4][5][6].Consider a large quantum system whose full characterization is only partially feasible or requires complex measurement schemes. In such a case, it is crucial to develop effective strategies in order to assess relevant pieces of information about the overall system by only monitoring a small part, which then acts as a probe. A natural procedure is to control the interaction of the small subsystem with the rest of the total system in such a way that the former can encode the information of interest. Here, we provide an explicit example of this strategy in an all-optical setup, where the system under study consists of entangled couples of photons generated by spontaneous parametric down conversion (SPDC) [7][8][9][10]. By properly engineering the interaction between polarization and momentum degrees of freedom of the photons via a 1D spatial light modulator (SLM), we can access some information regarding the momentum correlations between the two photons by simply performing visibility measurements on the polarization degrees of freedom.As specific figure of merit, we exploit the trace distance between polarization states. As we shall see, an increase of the trace distance above its initial value allows to detect some information on momentum correlations, which has moved to the polarization degrees of freedom thanks to the engineered interaction. The tracedistance analysis of quantum dynamics has been recently introduced, leading to important results concerning the non-Markovianity of a quantum dynamics [11][12][13][14][15][16], the characterization of the presence of initial correlations between the quantum system and its environment [17][18][19][20], the relevance of non-local memory effects [21][22][23] and the reservoir engineering in ultracold gases [24][25][26].The paper is structured as follows. In the next Section we describe the physical system we are go...

show abstract

Innovative method to investigate how the spatial correlation of the pump beam affects the purity of polarization entangled states

Cited by 4 publications

References 14 publications

Two-step procedure to discriminate discordant from classical correlated or factorized states

Two-step procedure to discriminate discordant from classical correlated or factorized states

Assessing the significance of fidelity as a figure of merit in quantum state reconstruction of discrete and continuous-variable systems

Quantum probes to experimentally assess correlations in a composite system

Contact Info

Product

Resources

About