Measuring quantumness: from theory to observability in interferometric setups

Ferro, L.; Fazio, Rosario; Illuminati, Fabrizio; Marmo, Giuseppe; Pascazio, Saverio; Vedral, Vlatko

doi:10.1140/epjd/e2018-90522-y

Cited by 13 publications

(15 citation statements)

References 35 publications

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“…The nonclassicality of quantum systems can be conveniently quantified using the Hilbert-Schmidt norm of the commutator of two states, which is proposed to witness the “state incompatibility” between any two admissible states ρ a and ρ b 3940. The “quantumness” is then defined as…”

Section: Quantum Speed Limit To the Dynamics Of Quantumnessmentioning

confidence: 99%

“…and Q(ρ a , ρ b ) = 0 iff [ ρ a , ρ b ] = 03940. Choosing ρ a = ρ 0 and ρ b = ρ t , Q (ρ 0 , ρ t ) allows one to quantify the capacity of an arbitrary physical process to generate or sustain quantumness in case of [ ρ 0 , ρ t ] ≠ 0.…”

Section: Quantum Speed Limit To the Dynamics Of Quantumnessmentioning

confidence: 99%

“…This transition is of particular relevance in composite quantum systems exhibiting non-classical correlations, with applications to a variety of fields38. To characterize the crossover between the quantum and classical worlds of a single physical system, one can define the notion of quantumness on the non-commutativity of the algebra of observables39 in a way that it is experimentally measurable40. In this framework a system is found to be classical if all its accessible states commute with each other.…”

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confidence: 99%

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Fundamental Speed Limits to the Generation of Quantumness

Jing

Campo

2016

Sci Rep

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Quantum physics dictates fundamental speed limits during time evolution. We present a quantum speed limit governing the generation of nonclassicality and the mutual incompatibility of two states connected by time evolution. This result is used to characterize the timescale required to generate a given amount of quantumness under an arbitrary physical process. The bound is found to be tight under pure dephasing dynamics. More generally, our analysis reveals the dependence on the initial and final states and non-Markovian effects.

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Section: Quantum Speed Limit To the Dynamics Of Quantumnessmentioning

confidence: 99%

Section: Quantum Speed Limit To the Dynamics Of Quantumnessmentioning

confidence: 99%

mentioning

confidence: 99%

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Fundamental Speed Limits to the Generation of Quantumness

Jing

Campo

2016

Sci Rep

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“…is the Bessel function of second order. This formula is valid for ω ≥ The problem with coherent states is that a beam splitter cannot change the entanglement degree of any state codified in them [21], so the dynamics is essentially classical [23][24][25][26][27][28].…”

mentioning

confidence: 99%

Invited Article: Quantum memristors in quantum photonics

2018

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We propose a method to build quantum memristors in quantum photonic platforms. We firstly design an effective beam splitter, which is tunable in real-time, by means of a Mach-Zehnder-type array with two equal 50:50 beam splitters and a tunable retarder, which allows us to control its reflectivity. Then, we show that this tunable beam splitter, when equipped with weak measurements and classical feedback, behaves as a quantum memristor. Indeed, in order to prove its quantumness, we show how to codify quantum information in the coherent beams. Moreover, we estimate the memory capability of the quantum memristor. Finally, we show the feasibility of the proposed setup in integrated quantum photonics.

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“…Quantum generalization of the Fisher information has also been introduced [45,46], which can be considered as a measure of non-classicality for quantum system [47,48]. A measure of quantumness has been proposed in a recent work [49], based on the non-commutativity of quantum states. We have shown that the Quantum Fisher information is lower bounded by the above mentioned quantumness with a factor of 1/4 and upper bounded by the l 1 norm of coherence with a factor of 1/2.…”

Section: Introductionmentioning

confidence: 99%

Evolution of coherence and non-classicality under global environmental interaction

Bhattacharya

Banerjee

Pati

2018

Quantum Inf Process

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A master equation has been constructed for a global system-bath interaction both in the absence as well as presence of non-Markovian noise. For the memoryless case, it has been exactly solved for a paradigmatic class of two qubit states in high and zero temperature thermal environment. For the non-Markovian model, it has been solved for zero temperature bath. The evolution of quantum coherence and entanglement has been observed in presence of the above mentioned interactions. We show that the global part of the system-bath interaction compensates for the decoherence, resulting in slow down of coherence and entanglement decay. For an appropriately defined limiting case, both coherence and entanglement show freezing behaviour for the high temperature bath. In case of zero temperature bath, the mentioned interaction not only stabilizes the non-classical correlations, but also enhances them for a finite period. For the memory dependent case, we have seen that the global interaction enhances the back-flow of information from environment to the system, as it enhances the regeneration of coherence and entanglement. Also we have studied the generation of Quantum Fisher information by the mentioned process. An intuitive measure of non-classicality based on non-commutativity of quantum states has been considered. Bounds on generated quantum Fisher information has been found in terms of quantumness and coherence. This gives us a novel understanding of Quantum Fisher information as a measure of non-classicality.

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Measuring quantumness: from theory to observability in interferometric setups

Cited by 13 publications

References 35 publications

Fundamental Speed Limits to the Generation of Quantumness

Fundamental Speed Limits to the Generation of Quantumness

Invited Article: Quantum memristors in quantum photonics

Evolution of coherence and non-classicality under global environmental interaction

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