Discord of response

Roga, Wojciech; Giampaolo, Salvatore Marco; Illuminati, Fabrizio

doi:10.1088/1751-8113/47/36/365301

Cited by 30 publications

(86 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[24] it shows that their role in metrology transcends specific schemes and Hilbert space dimensions. The formalism applied here can be immediately useful to calculate other discord-type quantities for Gaussian states, which capture geometrically their sensitivity under local unitary transformations, e.g., the local quantum uncertainty [31], the discriminating strength [42], and the discord of response [43] (see also [44]). …”

Section: Discussionmentioning

confidence: 99%

Gaussian interferometric power

Adesso

2014

Phys. Rev. A

View full text Add to dashboard Cite

The interferometric power of a bipartite quantum state quantifies the precision, measured by quantum Fisher information, that such a state enables for the estimation of a parameter embedded in a unitary dynamics applied to one subsystem only, in the worst-case scenario where a full knowledge of the generator of the dynamics is not available a priori. For finite-dimensional systems, this quantity was proven to be a faithful measure of quantum correlations beyond entanglement. Here we extend the notion of interferometric power to the technologically relevant setting of optical interferometry with continuous-variable probes. By restricting to Gaussian local dynamics, we obtain a closed formula for the interferometric power of all two-mode Gaussian states. We identify separable and entangled Gaussian states which maximize the interferometric power at fixed mean photon number of the probes and discuss the associated metrological scaling. At fixed entanglement of the probes, highly thermalized states can guarantee considerably larger precision than pure two-mode squeezed states.

show abstract

Section: Discussionmentioning

confidence: 99%

Gaussian interferometric power

Adesso

2014

Phys. Rev. A

View full text Add to dashboard Cite

show abstract

“…Notice that, in contrast with the case of a local measurement discussed in Section 2.3.1, a local unitary does not alter the correlations between A and B at all, yet can assess their nature based on the global change (or lack thereof) of the state ρ AB in response to the action of any such local unitary [41].…”

Section: 32mentioning

confidence: 97%

“…Moreover, they satisfy Requirement (ii) and, provided D δ is contractive, Requirement (iv) [41], whereas it is still an open question if they comply with Requirement (v). For pure states |ψ AB , any measure Q U δ A reduces to the corresponding "entanglement of response" [81],…”

Section: Unitary Response Measuresmentioning

confidence: 99%

See 1 more Smart Citation

Measures and applications of quantum correlations

Adesso¹,

Bromley²,

Cianciaruso³

2016

J. Phys. A: Math. Theor.

395

416

View full text Add to dashboard Cite

Abstract. Quantum information theory is built upon the realisation that quantum resources like coherence and entanglement can be exploited for novel or enhanced ways of transmitting and manipulating information, such as quantum cryptography, teleportation, and quantum computing. We now know that there is potentially much more than entanglement behind the power of quantum information processing. There exist more general forms of non-classical correlations, stemming from fundamental principles such as the necessary disturbance induced by a local measurement, or the persistence of quantum coherence in all possible local bases. These signatures can be identified and are resilient in almost all quantum states, and have been linked to the enhanced performance of certain quantum protocols over classical ones in noisy conditions. Their presence represents, among other things, one of the most essential manifestations of quantumness in cooperative systems, from the subatomic to the macroscopic domain. In this work we give an overview of the current quest for a proper understanding and characterisation of the frontier between classical and quantum correlations in composite states. We focus on various approaches to define and quantify general quantum correlations, based on different yet interlinked physical perspectives, and comment on the operational significance of the ensuing measures for quantum technology tasks such as information encoding, distribution, discrimination and metrology. We then provide a broader outlook of a few applications in which quantumness beyond entanglement looks fit to play a key role.

show abstract

“…The worst-case scenario is defined by the probability of error from equation (3) being the largest possible: Let us now consider a recently introduced measure of quantum correlations, the so-called discord of response [13]:…”

Section: Probability Of Error Bounds and Discord Of Responsementioning

confidence: 99%

Device-independent quantum reading and noise-assisted quantum transmitters

2015

Self Cite

View full text Add to dashboard Cite

In quantum reading, a quantum state of light (transmitter) is applied to read classical information. In the presence of noise or for sufficiently weak signals, quantum reading can outperform classical reading by reason of enhanced state distinguishability. Here we show that enhanced quantum efficiency depends on the presence in the transmitter of a particular type of quantum correlations, the discord of response. Different encodings and transmitters give rise to different levels of efficiency. Considering noisy quantum probes, we show that squeezed thermal transmitters with non-symmetrically distributed noise among the field modes yield higher quantum efficiency compared with coherent thermal quantum states. The noise-enhanced quantum advantage is a consequence of the discord of response being a non-decreasing function of increasing thermal noise under constant squeezing, a behavior that leads to increased state distinguishability. We finally show that, for non-symmetric squeezed thermal states, the probability of error, as measured by the quantum Chernoff bound, vanishes asymptotically with increasing local thermal noise with finite global squeezing. Therefore, with fixed finite squeezing, noisy but strongly discordant quantum states with a large noise imbalance between the field modes can outperform noisy classical resources as well as pure entangled transmitters with the same finite level of squeezing.

show abstract

Discord of response

Cited by 30 publications

References 54 publications

Gaussian interferometric power

Gaussian interferometric power

Measures and applications of quantum correlations

Device-independent quantum reading and noise-assisted quantum transmitters

Contact Info

Product

Resources

About