Entanglement and the speed of evolution in mixed states

Kupferman, Judy; Reznik, Benni

doi:10.1103/physreva.78.042305

Cited by 33 publications

(24 citation statements)

References 15 publications

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“…This is a striking result, clearly distinct from the one corresponding to unitary evolution. It has already been seen in the literature [22][23][24][25][26] that, for unitary processes, entanglement is a resource that enhances the speed of evolution, so that the separation time improves from a τ ∼ 1/ √ N scaling (separable, slow state) to τ ∼ 1/N (entangled, fast state). However, for the nonunitary evolution here considered, the minimum evolution time for separable states, while scaling with 1/ √ N for small N , eventually scales as 1/N for γ √ N ≫ ω 0 , no matter how small is the dephasing rate.…”

mentioning

confidence: 99%

Quantum Speed Limit for Physical Processes

Taddei

Escher

Filho

2013

The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement Meeting

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The evaluation of the minimal evolution time between two distinguishable states of a system is important for assessing the maximal speed of quantum computers and communication channels. Lower bounds for this minimal time have been proposed for unitary dynamics. Here we show that it is possible to extend this concept to nonunitary processes, using an attainable lower bound that is connected to the quantum Fisher information for time estimation. This result is used to delimit the minimal evolution time for typical noisy channels.

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confidence: 99%

Quantum Speed Limit for Physical Processes

Taddei

Escher

Filho

2013

The Rochester Conferences on Coherence and Quantum Optics and the Quantum Information and Measurement Meeting

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“…First of all, one has to generalize simple formula (10), which seems a natural definition of the 'non-decay probability' for pure states. The authors of papers [128,131] considered the 'relative purity'…”

Section: Margolus-levitin Inequalities and Their Generalizationsmentioning

confidence: 99%

Energy–time and frequency–time uncertainty relations: exact inequalities

Dodonov

Додонов

2015

Phys. Scr.

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We give a short review of known exact inequalities that can be interpreted as 'energy-time' and 'frequency-time' uncertainty relations. In particular we discuss a precise form of signals minimizing the physical frequencytime uncertainty product. Also, we calculate the 'stationarity time' for mixed Gaussian states of a quantum harmonic oscillator, showing explicitly that pure quantum states are 'more fragile' than mixed ones with the same value of the energy dispersion. The problems of quantum evolution speed limits, time operators and measurements of energy and time are briefly discussed, too. This is our present to Margarita Alexandrovna and Vladimir Ivanovich Man'ko on occasion of their 75th birthdays. ‡ Heisenberg and Bohr used the symbols = or ∼ instead of . arXiv:1504.00862v1 [quant-ph] 3 Apr 2015Energy-time and frequency-time uncertainty relations: exact inequalities

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“…The QSL bounds were first investigated for the unitary dynamics of pure states [1,2,. Later, QSL has been studied for the case of unitary dynamics of mixed states [27][28][29][30][31][32][33][34][35][36], unitary dynamics of multipartite systems [37][38][39][40] and for more general dynamics [41][42][43][44][45][46]. The study of QSL is significant for theoretical understanding of quantum dynamics and has relevance in developing quantum technologies and devices, etc.…”

Section: Introductionmentioning

confidence: 99%