Disorder-Induced Dephasing in Backscattering-Free Quantum Transport

We study the disorder-perturbed transport of two noninteracting entangled particles in the absence of backscattering. This situation is, for instance, realized along edges of topological insulators. We find profoundly different responses to disorder-induced dephasing for the center-of-mass and relative coordinates: While a mirror symmetry protects even highly delocalized relative states when resonant with the symmetry condition, delocalizations in the center of mass (e.g. two-particle (N = 2) N 00N states) remain fully sensitive to disorder. We demonstrate the relevance of these differences to the example of interferometric entanglement detection. Our platform-independent analysis is based on the treatment of disorder-averaged quantum systems with quantum master equations.

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“…Ref. [5]), the latter experiences coherent momentum kicks in opposing directions. The solution of Eq.…”

Section: Disorder-averaged Evolutionmentioning

confidence: 99%

“…We consider backscattering-free propagation of two spinless quantum particles in one dimension, described by a common, constant drift velocity v. This generalizes the single-particle case discussed in Ref. [5]. To be general, we consider two distinguishable particles.…”

Section: Disorder-averaged Evolutionmentioning

confidence: 99%

Disorder-Robust Entanglement Transport

2019

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“…This will allow us to assess the disorderinduced backscattering in two ways complementary to the previous analysis in terms of the localization length: first, by directly observing the appearance of backscattering peaks, and second, indirectly by tracking the purity evolution of the disorder-averaged state. In case of backscattering-free propagation, the purity decays to a characteristic plateau value, indicating the unavoidable disorder-induced dephasing [42]. Strong deviations from this plateau value, i.e., increasing overshooting, can then be taken as a signature of backscattering, since the latter also adds to the mixing of the disorder-averaged state and thus to its purity decay.…”

Section: Pulse Propagationmentioning

confidence: 99%

“…Purity evolution for moderate disorder strength W = 0.5J with ensemble size 400. Black line is the analytic result from[42]. We use the effective correlation length l = 2d.…”

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confidence: 99%

Helical transport in coupled resonator waveguides

2019

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We show that a synthetic pseudospin-momentum coupling can be used to design quasi-onedimensional disorder-resistant coupled resonator optical waveguides (CROW). In this structure, the propagating Bloch waves exhibit a pseudospin-momentum locking at specific momenta where backscattering is suppressed. We quantify this resistance to disorder using two methods. First, we calculate the Anderson localization length ξ, obtaining an order of magnitude enhancement compared to a conventional CROW for typical device parameters. Second, we study propagation in the time domain, finding that the loss of wavepacket purity in the presence of disorder rapidly saturates, indicating the preservation of phase information before the onset of Anderson localization. Our approach of directly optimizing the bulk Bloch waves is a promising alternative to disorder-robust transport based on higher dimensional topological edge states. arXiv:1902.06697v3 [physics.optics]

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“…This is relevant since systems whose internal system structure is not necessarily PT-symmetric (e.g. disordered systems [19,41]), may satisfy the PTsymmetry condition in its system constitutive matrix. Consider here as an example the case of d p = / k 4, for which the matrix ϒ becomes…”

Section: Gauged Pt-symmetry Conditionmentioning

confidence: 99%

Unidirectional zero reflection as gauged parity-time symmetry

et al. 2017

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We introduce here the concept of establishing parity-time (PT)-symmetry through a gauge transformation involving a shift of the mirror plane for the parity operation. The corresponding unitary transformation on the system's constitutive matrix allows us to generate and explore a family of equivalent PT-symmetric systems. We further derive that unidirectional zero reflection for a reciprocal two-port system can always be associated with a passively gauged PT-symmetry. We demonstrate this experimentally using a microstrip transmission-line with magnetoelectric coupling. This study allows us to use bianisotropy as a practical route to realise and explore exceptional point behaviour of PT-symmetric or generally non-Hermitian systems.

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Disorder-Induced Dephasing in Backscattering-Free Quantum Transport

Cited by 20 publications

References 30 publications

Disorder-Robust Entanglement Transport

Disorder-Robust Entanglement Transport

Helical transport in coupled resonator waveguides

Unidirectional zero reflection as gauged parity-time symmetry

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