The effect of turbulence on entanglement-based free-space quantum key distribution with photonic orbital angular momentum

Goyal, Sandeep K.; Ibrahim, Alpha Hamadou; Roux, Filippus S.; Konrad, Thomas; Forbes, Andrew

doi:10.1088/2040-8978/18/6/064002

Cited by 39 publications

(35 citation statements)

References 62 publications

(85 reference statements)

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“…The decay of entanglement in biphoton states that are entangled in there spatial degrees of freedom has been studied theoretically [7][8][9][10][11][12][13], numerically [14], as well as experimentally [15][16][17][18]. There has also been a number of demonstrations of the use of OAM modes for the implementation of classical free-space communication links [19,20] in addition to the free-space entanglement-based quantum key distribution, using OAM qubits [21,22].…”

Section: Introductionmentioning

confidence: 99%

Biphoton states in correlated turbulence

Roux

2017

Phys. Rev. A

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The effect of turbulence on a pair of photons propagating together through the same medium is analyzed. The behavior is compared to the case where these photons propagate separately through different turbulent media. The analysis is done with a multiple phase screen approach, by deriving and solving an infinitesimal propagation equation. We apply these results to the case where the initial photons are entangled in their spatial degrees of freedom with the aid of spontaneous parametric down-conversion. It is found that for this input state, the decay of entanglement in correlated media under the weak scintillation approximation is quicker than in uncorrelated media. Beyond the weak scintillation approximation, the entanglement in correlated media decays slower when it is close to zero -approaching zero asymptotically as a function of scintillation strength. This is contrary to the case in uncorrelated media where entanglement becomes zero at a finite scintillation strength.

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Section: Introductionmentioning

confidence: 99%

Biphoton states in correlated turbulence

Roux

2017

Phys. Rev. A

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“…As such, the polarisation is unaffected during propagation. The spatial degree of freedom however is highly susceptible to atmospheric turbulence, causing a scattering among OAM states [97][98][99][100][101]. Let us consider vector modes of a given OAM subspace .…”

Section: Propagation Through Perturbing Mediamentioning

confidence: 99%

Creation and Detection of Vector Vortex Modes for Classical and Quantum Communication

Ndagano

Nape

Cox

et al. 2018

J. Lightwave Technol.

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257

128

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Vector vortex beams are structured states of light that are non-separable in their polarisation and spatial mode, they are eigenmodes of free-space and many fibre systems, and have the capacity to be used as a modal basis for both classical and quantum communication. Here we outline recent progress in our understanding of these modes, from their creation to their characterization and detection. We then use these tools to study the propagation behaviour of such modes in free-space and optical fibre and show that modal cross-talk results in a decay of vector states into separable scalar modes, with a concomitant loss of information. We present a comparison between probabilistic and deterministic detection schemes showing that the former, while ubiquitous, negates the very benefit of increased dimensionality in quantum communication while reducing signal in classical communication links. This work provides a useful introduction to the field as well as presenting new findings and perspectives to advance it further.

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“…We'll refer to it as the weak scintillation scale. Previously, it was identified as the scale at which quantum entanglement decays to zero [15,16,20]. However, such an observation was based on the fact that all those analyses were done for quantum entanglement within the SPS approximation.…”

Section: F Comparing Weak and Strong Scintillationmentioning

confidence: 99%

“…Various studies have been done to understand and clarify the effect of scintillation on the OAM of optical fields [10][11][12][13][14][15][16][17][18][19][20]. Most of the theoretical studies are based on a single-phase screen (SPS) approximation [21], which assumes that the effect of turbulence on a propagating optical field can be represented by a single random phase modulation.…”

Section: Introductionmentioning

confidence: 99%

Optical orbital angular momentum under strong scintillation

Mabena

Roux

2019

Phys. Rev. A

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The evolution of classical optical fields propagating through atmospheric turbulence is investigated under arbitrary conditions. We use the single-phase screen (SPS) method and the infinitesimal propagation equation (IPE), a multi-phase screen (MPS) method, to compute the optical power fractions retained in an input Laguerre-Gauss (LG) mode or transferred to higher order LG modes. Although they show the same trend while the scintillation is weak, the IPE and SPS predictions deviate when the strength of scintillation passes a certain threshold. These predictions are compared with numerical simulations of optical fields propagating through turbulence. The simulations are performed using an MPS model, based on the Kolmogorov theory of turbulence, for different turbulence conditions to allow comparison in both weak and strong scintillation. The numerical results agree well with the IPE results in all conditions, but deviate from the SPS results for strong scintillation.

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The effect of turbulence on entanglement-based free-space quantum key distribution with photonic orbital angular momentum

Cited by 39 publications

References 62 publications

Biphoton states in correlated turbulence

Biphoton states in correlated turbulence

Creation and Detection of Vector Vortex Modes for Classical and Quantum Communication

Optical orbital angular momentum under strong scintillation

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