Statistical properties of intense twin beams

Project leaders

Maria Bondani, Jan Perina

Agreement

REPUBBLICA CECA - CAS (ex AVCR) - Czech Academy of Sciences

Call

CNR-CAS (ex AVCR) 2016-2018

Department

Physical sciences and technologies of matter

Thematic area

Physical sciences and technologies of matter

Status of the project

New

Research proposal

Intense twin beams have recently become an interesting research subject due to their nonclassical intensity correlations [Jedrkiewicz2004,Bondani2007,Blanchet2008] originating at the quantum level of the nonlinear generation process that emits photons in pairs [Mandel1995]. In intense twin beams, the purely quantum behavior of photon pairs is transformed into 'macroscopic' fields due to a huge number of photon pairs present in a twin beam [Boyd2003]. This results in strong correlations between two beams of a twin beam observed both in the spectral and spatial domains [Allevi2014a,Sharapova2015]. They even allows for sub-shot-noise quantum imaging [Brida2010]. Moreover, strong correlations are responsible for ideally pairwise character of the joint photon-number distributions [Haderka2005,PerinaJr2012]. For weaker twin beams, this statistics is thermal due to the spontaneity of emission of photon pairs [Perina2005,Gatti2003,Brambilla2010]. At present, interesting modifications of spatio-spectral coherence of twin beams have been found provided that pump depletion is observed during the generation [Allevi2014]. Pump depletion has been found responsible for the suppression of the growth of coherence with the increasing pump intensity observed at lower pump intensities. This loss of coherence at high intensities has been explained by the internal dynamics of twin beams that consist of many independent triples of internal modes [Allevi2014a]. Some of the most intensively populated pump modes undergo depletion or they even loose their energy completely inside a nonlinear crystal. According to quantum mechanics, this effect should be accompanied by the gradual change of statistical character of the intense twin beam [Perina1991]. A coherent component of the twin beam, on the top of the thermal one, should be gradually developed. This is extraordinarily interesting, as the presence of coherent component indicates the transition to classical properties of twin beams. Among others, it weakens the ideal pairwise character of weak twin beams which is indicated by the decrease of the sub-shot-noise photon-number correlations. However, the experimental investigation of this transition is difficult, as twin beams composed of only small number of modes [Perez2014] can provide the evidence of this transition. This is one of the reasons why statistical properties of very intense twin beams have not been investigated yet.
This project aims at the investigation of statistical properties of such intense twin beams with the main motivation to observe a coherent component predicted by quantum mechanics. As the coherent component can be visible only for twin beams composed of low number of spatio-spectral modes, wide experimental investigations of spatio-spectral coherence of twin beams are necessary to succeed in this effort.

To this aim, statistical properties of intense twin beams will be investigated to reduce the number of independent spatio-spectral modes as much as possible, while keeping strong pairwise correlations between the beams. Spatial and spectral coherence of intense twin beams will be experimentally investigated under suitable conditions, like in the pump-depletion regime in which the number of modes can decrease. For intense twin beams, the generation of a coherent component on the top of the usual thermal component is theoretically predicted but not yet experimentally measured. The project will also address this problem by devising a proper measurement strategy and developing an appropriate theory for this case.

[Allevi2014] A. Allevi, M. Bondani: J. Opt. Soc. Am. B 31, B14 (2014).
[Allevi2014a] A. Allevi, O. Jedrkiewicz, E. Brambilla, A. Gatti, J. PeYina Jr., O. Haderka, M. Bondani: Phys. Rev. A 90, 063812 (2014).
[Blanchet2008] J.-L. Blanchet, F. Devaux, L. Furfaro, E. Lantz: Phys. Rev. Lett. 101, 233604 (2008).
[Bondani2007] M. Bondani, A. Allevi, G. Zambra, M. G. A. Paris, A. Andreoni: Phys. Rev. A 76, 013833 (2007).
[Boyd2003] R. W. Boyd: Nonlinear Optics (Academic Press, New York, 2003), 2nd edition.
[Brambilla2010] E. Brambilla, L. Caspani, L. A. Lugiato, A. Gatti: Phys. Rev. A 82, 013835 (2010).
[Brida2010] G. Brida, M. Genovese, I. R. Berchera: Nat. Phys. 4, 227 (2010).
[Gatti2003] A. Gatti, R. Zambrini, M. San Miguel, L. A. Lugiato: Phys. Rev. A 68, 053807 (2003).
[Haderka2005a] O. Haderka, J. PeYina Jr., M. Hamar, J. PeYina: Phys. Rev. A 71, 033815 (2005).
[Jedrkiewicz2004] O. Jedrkiewicz, Y. K. Jiang, E. Brambilla, A. Gatti, M. Bache, L. A. Lugiato, P. Di Trapani, Phys. Rev. Lett. 93, 243601 (2004).
[Mandel1995] L. Mandel, E. Wolf: Optical Coherence and Quantum Optics (Cambridge Univ. Press, Cambridge, 1995).
[Perez2014] A. M. Perez, T. S. Iskhakov, P. Sharapova, S. Lemieux, O. V. Tikhonova, M. V. Chekhova, G. Leuchs: Opt. Lett. 39, 2403 (2014).
[Perina1991] J. PeYina: Quantum Statistics of Linear and Nonlinear Optical Phenomena (Kluwer, Dordrecht, 1991).
[Perina2005] J. PeYina, J. KYepelka: J. Opt. B: Quant. Semiclass. Opt. 7, 246 (2005).
[PerinaJr2012] J. {PeYina Jr., M. Hamar, V. Michálek, O. Haderka: Phys. Rev. A 85, 023816 (2012).
[Sharapova2015] P. Sharapova, A. M. Perez, O. V. Tikhonova, M. V. Chekhova: Phys. Rev. A 91, 043816 (2015).

Research goals

The main objective of the project is to investigate the statistical properties of intense twin beams as they change at the transition from the low intensity regime up to that of pump depletion. Hand in hand, spatio-spectral coherence of twin beams will be investigated. The results will elucidate the transition of twin beams from their (low intensity) quantum form into the high-intensity (close to classical) form. Such micro-macro transition is of extraordinary importance to elucidate the relation between quantum and classical physics.

The investigation of statistical properties of twin beams will be performed experimentally using suitable nonlinear crystals and high-power lasers. The generated twin beams will be detected by EMCCD and iCCD cameras that will provide the information about both spatial coherence and statistical properties of twin beams. The use of a monochromator will give the information about spectral coherence of twin beams. The experimental results will be compared with theoretical models already partially developed. Modifications of the models will be introduced to account for the achieved experimental results. This will help to optimize the experimental conditions for the measurement of the joint photon-number statistics.

Last update: 19/04/2024