Entanglement dynamics in the presence of controlled unital noise

Shaham, Assaf; Halevy, Ayelet; Dovrat, L.; Megidish, Eli; Eisenberg, Henryk

doi:10.1038/srep10796

Cited by 12 publications

(9 citation statements)

References 23 publications

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“…3. Unital quantum noises have speci¯c interesting properties [41][42][43], and many common qubit noises belong to this class, such as bit-°ip, or phase-°ip, or depolarizing noises, or the whole family of Pauli noises we will consider below. For quantum estimation processes, stochastic resonance or e®ects of enhancement by noise have never been reported with unital quantum noises.…”

Section: Phase Estimation On a Noisy Qubitmentioning

confidence: 99%

Stochastic Resonance with Unital Quantum Noise

2019

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The fundamental quantum information processing task of estimating the phase of a qubit is considered. Following quantum measurement, the estimation efficiency is evaluated by the classical Fisher information which determines the best performance limiting any estimator and achievable by the maximum likelihood estimator. The estimation process is analyzed in the presence of decoherence represented by essential quantum noises that can affect the qubit and belonging to the broad class of unital quantum noises. Such a class especially contains the bit-flip, the phase-flip, the depolarizing noises, or the whole family of Pauli noises. As the level of noise is increased, we report the possibility of non-standard behaviors where the estimation efficiency does not necessarily deteriorate uniformly, but can experience non-monotonic variations. Regimes are found where higher noise levels prove more favorable to estimation. Such behaviors are related to stochastic resonance effects in signal estimation, shown here feasible for the first time with unital quantum noises. The results provide enhanced appreciation of quantum noise or decoherence, manifesting that it is not always detrimental for quantum information processing.

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Section: Phase Estimation On a Noisy Qubitmentioning

confidence: 99%

Stochastic Resonance with Unital Quantum Noise

2019

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“…Quantum channel Φ : B(H) → B(H) is a completely positive trace-preserving map that describes the result of quantum system transformation due to unavoidable interaction with environment (quantum noise) [12][13][14]. The longer the quantum channels between the entanglement source and laboratories A, B, the noisier and less entangled becomes the output state, [15][16][17][18][19][20]. The length of the quantum channels can be included in the above description by time t quantifying the duration of the system-environment interaction:…”

Section: Introductionmentioning

confidence: 99%

Ultimate entanglement robustness of two-qubit states against general local noises

2018

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We study the problem of optimal preparation of a bipartite entangled state, which remains entangled the longest time under action of local qubit noises. We show that for unital noises such a state is always maximally entangled, whereas for nonunital noises, it is not. We develop a decomposition technique relating nonunital and unital qubit channels, based on which we find the explicit form of the ultimately robust state for general local noises. We illustrate our findings by amplitude damping processes at finite temperature, for which the ultimately robust state remains entangled up to two times longer than conventional maximally entangled states.

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“…The future of large-scale quantum communications will almost certainly involve distribution and manipulation of entangled pairs of photons within a quantum network; such a quantum network is likely to include small clusters of quantum processors (perhaps in a local network of quantum computers) which may require shared entanglement, and could then be connected to other network clusters, potentially via satellite communications [1][2][3]. However, despite the undeniably useful non-classical properties which entanglement-based quantum systems offer (such as for quantum key distribution [4][5][6][7], quantum secret sharing [8][9][10], quantum repeaters [11][12][13][14], quantum computing [15][16][17][18] and quantum teleportation [19][20][21][22]), entanglement is a highly fragile resource, and breaks down rapidly in the presence of noise and losses [23].…”

Section: Introductionmentioning

confidence: 99%

Photonic hybrid state entanglement swapping using cat state superpositions

Parker

Joo²,

Spiller

2020

Proc. R. Soc. A.

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We propose the use of hybrid entanglement in an entanglement swapping protocol, as means of distributing a Bell state with high fidelity to two parties. The hybrid entanglement used in this work is described as a discrete variable (Fock state) and a continuous variable (cat state super- position) entangled state. We model equal and unequal levels of photonic loss between the two propagating continuous variable modes, before detecting these states via a projective vacuum-one-photon measurement, and the other mode via balanced homodyne detection. We investigate homodyne measurement imperfections, and the associated success probability of the measurement schemes chosen in this protocol. We show that our entanglement swapping scheme is resilient to low levels of photonic losses, as well as low levels of averaged unequal losses between the two propagating modes, and show an improvement in this loss resilience over other hybrid entanglement schemes using coherent state superpositions as the propagating modes. Finally, we conclude that our protocol is suitable for potential quantum networking applications which require two nodes to share entanglement separated over a distance of 5 -- 10 km , when used with a suitable entanglement purification scheme.

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Entanglement dynamics in the presence of controlled unital noise

Cited by 12 publications

References 23 publications

Stochastic Resonance with Unital Quantum Noise

Stochastic Resonance with Unital Quantum Noise

Ultimate entanglement robustness of two-qubit states against general local noises

Photonic hybrid state entanglement swapping using cat state superpositions

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