Production of bright entangled photons from moving optical boundaries

Abstract

We discuss a mechanism of generating two separable beams of light with high degree of entanglement in momentum using a fast and sharp optical boundary. Three regimes of light generation are identified depending on the number of resonant interactions between the optical perturbation and the electromagnetic field. The intensity of the process is discussed in terms of the relevant physical parameters: variation of refractive index and apparent velocity of the optical boundary. Our results suggest a different class of generation entangled light robust against thermal degradation by exciting zero point fluctuations using parametric resonant optical modulations. PACS numbers:Introduction. Many of the theoretical schemes and experimental applications being proposed and developed in the context of Quantum Information (QI) (including quantum computation and information processing [1], teleportation [2], etc.) rely on the generation of entanglement between different quantum systems. Though entanglement can arise in nature even from the simplest interactions and even at high temperature [3,4], the degree of entanglement achieved is usually very small. An important exception are photons, which combined with their resilience to thermal effects, can be used, for example, to establish quantum communication at long-distances [5]. Till now, entangled photons are produced experimentally via parametric down conversion (PDC), which is in general a nonlinear process with small efficiency [6,7].

Laser pulse analogues for gravity and analogue Hawking radiation

“…However, this is not generally considered to be conclusive evidence and further measurements are called for in order to verify some open issues: the measured photon numbers, of the order of 0.1-0.01 photons/pulse, appear to be too high to be accounted for on the basis of a blackbody emission. Yet other models [20] appear to give predictions that confirm the measurements. Moreover, the theory predicts that photons will be generated in correlated pairs.…”

“…We note that although relation (9) was not originally derived from a dispersive theory, recent models that account also for dispersion arrive at exactly the same equation (see e.g. [20]) where n 0 ¼ n 0 (o) is the medium phase index. This equation therefore represents the fundamental relation against which one may compare measurements in order to verify if any observed radiation may be related to the presence of an horizon.…”

“…there is a 'temporal boundary', then the frequency of light is modified. These ideas were then extended to account for quantum effects and, of particular interest in this context, included also the quantum vacuum and excitation of entangled photon pairs [18][19][20]. Over the last 10 years a number of papers have returned to the problem of light in moving media within the specific context of analogue gravity and with the explicit goal of evaluating the analogy between these systems and gravitational black holes [21][22][23][24][25][26][27][28][29][30][31][32].…”

Belgiornoet al.Reply:

“…However this model was excluded as it is a distinct effect from Hawking emission and does not capture the main spectral features of [5]. Finally, two very recent non-perturbative models for Hawking emission that include dispersion both predict photon numbers that are of the same order of magnitude [8] or higher than in the measurements [9].…”

Blackbody Emission from Light Interacting with an Effective Moving Dispersive Medium

“…Based on these results, diamond is proposed as a promising candidate medium for future studies of Hawking emission from artificial, dispersive horizons.Recent developments in the understanding of light propagation have led to evidence that by using intense laser pulses propagating in a nonlinear medium, it is possible to create an effective medium that flows with the same speed as the laser pulse, i.e. at speeds close to or, as a consequence of dispersion, even higher than the speed of light at other frequencies in the medium [1][2][3][4][5][6][7][8][9]. Indeed, in a medium with a third order (also called "Kerr") nonlinear polarisation response the refractive index of the medium is given by n = n 0 +n 2 I(z −vt), where n 0 is the background index, n 2 is the nonlinear Kerr index and I(z − vt) is the laser pulse intensity profile, travelling along the z direction with velocity v. In a typical condensed medium, e.g.…”