Rating the performance of noisy teleportation using fluctuations in fidelity

Roy, Saptarshi; Ghosal, Arkaprabha

doi:10.1103/physreva.102.012428

Cited by 9 publications

(10 citation statements)

References 65 publications

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“…Fidelity deviation δ ρ is a secondary quantifier of QT which measures fluctuations in fidelity over the input states. It is defined as the standard deviation of fidelity over all input states given by [16][17][18][19],…”

Section: B Hilbert-schmidt Representation and The Canonical Form Of A...mentioning

confidence: 99%

“…However, in reality one cannot expect maximally entangled states due to environmental interactions leading to imperfect QT, where the average fidelity is strictly less than one [12]. Though average fidelity is the standard quantifier for QT, it does not contain any information about the dispersion in fidelity over the input states or fidelity deviation [16][17][18][19]. In case of imperfect QT, dispersion or fluctuation in fidelity may arise.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing qubit channels in the context of quantum teleportation

Ghosal,

Das,

Banerjee

2021

Preprint

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We consider a scenario where a party, say, Alice prepares a pure two-qubit (either maximally entangled or non-maximally entangled) state and sends one half of this state to another distant party, say, Bob through a qubit (either unital or non-unital) channel. Finally, the shared state is used as a teleportation channel. In this scenario, we focus on characterizing the set of qubit channels in terms of the final state's efficacy as a resource of quantum teleportation (QT) in terms of maximal average fidelity and fidelity deviation (fluctuation in fidelity values over the input states). Importantly, we point out the existence of a subset of qubit channels for which the final state becomes useful for universal QT (having maximal average fidelity strictly greater than the classical bound and having zero fidelity deviation) when the initially prepared state is either useful for universal QT (i.e., for maximally entangled state) or not useful for universal QT (i.e., for a subset of non-maximally entangled pure states). Interestingly, in the latter case, we show that non-unital channels (dissipative interactions) are more effective than unital channels (non-dissipative interactions) in producing useful states for universal QT from non-maximally entangled pure states.

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Section: B Hilbert-schmidt Representation and The Canonical Form Of A...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterizing qubit channels in the context of quantum teleportation

Ghosal,

Das,

Banerjee

2021

Preprint

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“…Recently, fidelity deviation [17][18][19][20][21][22] in quantum teleportation has got considerable attention. It is important to study this quantity as it gives the idea of fluctuations associated with teleportation fidelity.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the duo, teleportation fidelity and its deviation contain more information to characterize quantum teleportation than the teleportation fidelity alone. However, fidelity deviation has been studied considering different resource states [18,19,21] and other constraints [20,22]. In these articles, it has also been argued that the states which can lead to both non-classical fidelity and zero fidelity deviation, are the most desired states as resource in quantum teleportation.…”

Section: Introductionmentioning

confidence: 99%

Teleportation fidelity and its deviation for an arbitrary two-qubit state when the classical communication is noisy

Bej¹,

Halder²,

Sengupta³

2021

Preprint

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In this work, we consider the following teleportation protocol: There is an arbitrary two-qubit resource state, shared between two spatially separated parties, Alice and Bob. Applying local unitary operators, they transform the resource state into the canonical form. To teleport an unknown qubit, Alice now measures her qubits in the Bell basis. Then, the measurement outcome is communicated by Alice to Bob via noisy classical channel(s). Finally, after receiving the classical message, Bob applies the necessary unitary operator to his qubit. Under this protocol, we find the exact formulae of teleportation fidelity and its deviation. We further find conditions for non-classical fidelity within this protocol. If the classical communication is noiseless in the above protocol then there are resource states which can lead to zero fidelity deviation. However, we show that such states may not lead to zero fidelity deviation when the classical communication is noisy in the same protocol. We also explore the opposite case, i.e., the states, which cannot lead to zero fidelity deviation in the above protocol when the classical communication is noiseless, may lead to zero fidelity deviation when the classical communication is noisy in the same protocol without compromising the non-classical fidelity. Moreover, we exhibit scenarios within the present protocol, where the fidelity deviation increases if the entanglement of the resource state is increased.

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“…We characterize the nonclassicality of teleportation protocol via average fidelity where the averaging is performed over the corresponding distribution of inputs. In addition, we also evaluate fidelity deviation which indicates for a given channel, how different states get teleported far from the target state [36] (see also [37][38][39][40]). In case of the polar cap as well as von Mises-Fisher distributions, we obtain compact forms of average fidelities for arbitrary two-qubit density matrices in terms of the correlation matrix and show that similar formalisms can also be applied to obtain fidelity deviations.…”

Section: Introductionmentioning

confidence: 99%

Gain in Performance of Teleportation with Uniformity-breaking Distributions

Roy,

Mal,

2020

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Prior information about the input state can be utilized to enhance the efficiency of quantum teleportation which we quantify using the first two moments of fidelity. The input knowledge is introduced by relaxing the uniformity assumption in the distribution of the input state and considering non-uniform distributions, namely the polar cap and von Mises-Fisher densities. For these distributions,we show that the average fidelity increases while the deviation decreases with the increase of information content about the input ensemble thereby establishing its role as a resource. Our comparative study between these two distributions reveals that for the same amount of information content about inputs, although the average fidelity yield is the same for both, the polar cap distribution is "better" as it offers a smaller deviation. Moreover, we contrast the resource of prior information with other resources involved in the protocol like shared entanglement and classical communication. Specifically, we observe that unlike uniform distribution, the amount of classical communication required to fulfill the task decreases with the increase of information available for inputs. We also investigate the role of prior information in higher (three) dimensional teleportation and report the signatures of dimensional advantage in prior information-based teleportation.

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Rating the performance of noisy teleportation using fluctuations in fidelity

Cited by 9 publications

References 65 publications

Characterizing qubit channels in the context of quantum teleportation

Characterizing qubit channels in the context of quantum teleportation

Teleportation fidelity and its deviation for an arbitrary two-qubit state when the classical communication is noisy

Gain in Performance of Teleportation with Uniformity-breaking Distributions

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