Physical review. B./Physical review. B

Effective production of orbital quantum entanglement in chaotic quantum dots with nonideal contacts

Eduardo H. Santos, Francisco A. G. Almeida

Published Sep 27, 2016• 2 citations

Abstract

We study orbital entanglement production in a chaotic quantum dot with two-channel leads by varying the opacity of the contacts in the unitary and orthogonal Wigner-Dyson ensembles. We computed the occurrence probability of entangled states (squared norm) and its concurrence (entanglement level). We also define an entanglement production factor to properly evaluate the entanglement behavior in the system considering effective aspects. The results are numerically obtained through (i) integrations over random matrix ensembles (exact results) for the scenario of one contact ideally fixed and (ii) random matrix simulations for arbitrary contact opacities (sampling). Those outcomes are in mutual agreement and indicate that the optimum effective production of orbital entanglement is achieved when both contacts are ideal and the time-reversal symmetry is broken.

DOI: 10.1103/physrevb.94.125441

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Physical review. B./Physical review. B

Effective production of orbital quantum entanglement in chaotic quantum dots with nonideal contacts

Eduardo H. Santos, Francisco A. G. Almeida

Published Sep 27, 2016• 2 citations

Publisher

Abstract

DOI: 10.1103/physrevb.94.125441

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We compute analytically the distributions of concurrence

\bm{\mathcal{C}}

and squared norm

\bm{\mathcal{N}}

for the production of electronic entanglement in a chaotic quantum dot. The dot is connected to the external world via one ideal and one partially transparent lead, characterized by the opacity

\gamma

. The average concurrence increases with

\gamma

while the average squared norm of the entangled state decreases, making it less likely to be detected. When a minimal detectable norm

\bm{\mathcal{N}}_0

is required, the average concurrence is maximal for an optimal value of the opacity

\gamma^\star(\bm{\mathcal{N}}_0)

which is explicitly computed as a function of

\bm{\mathcal{N}}_0

. If

\bm{\mathcal{N}}_0

is larger than the critical value

\bm{\mathcal{N}}_0^\star\simeq 0.3693\dots

, the average entanglement production is maximal for the completely ideal case, a direct consequence of an interesting bifurcation effect.

We compute analytically the distributions of concurrence

\text{C}

and squared norm

\text{N}

for the production of electronic entanglement in a chaotic quantum dot. The dot is connected to the external world via one ideal and one partially transparent lead, characterized by the opacity $\ensuremath{\gamma}$. The average concurrence increases with $\ensuremath{\gamma}$ while the average squared norm of the entangled state decreases, making it less likely to be detected. When a minimal detectable norm

{\text{N}}_{0}

is required, the average concurrence is maximal for an optimal value of the opacity ${\ensuremath{\gamma}}^{\ensuremath{\star}}({\text{N}}_{0})$ which is explicitly computed as a function of

{\text{N}}_{0}

. If

{\text{N}}_{0}

is larger than the critical value ${\text{N}}_{0}^{\ensuremath{\star}}\ensuremath{\simeq}0.3693\ensuremath{\cdots}$, the average entanglement production is maximal for the completely ideal case, a direct consequence of an interesting bifurcation effect.