Witnessing quantum coherence in the presence of noise

Monràs, Alex; Chęcińska, Agata; Ekert, Artur

doi:10.1088/1367-2630/16/6/063041

Cited by 33 publications

(20 citation statements)

References 37 publications

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“…Recent evidence suggests that a fruitful interplay between long-lived quantum coherence and tailored noise may be in fact crucial to enhance certain biological processes, such as light harvesting [27,28,30,31]. This surprising cooperation between traditionally competing phenomena provides an inspiration to explore other physical contexts, such as quantum information science, in order to look for general conditions under which coherence can be sustained in the presence of typical sources of noise [54,55]. Progress on this fundamental question can lead to a more efficient exploitation of coherence to empower the performance of real-world quantum technologies.…”

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confidence: 99%

Frozen Quantum Coherence

2015

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We analyze under which dynamical conditions the coherence of an open quantum system is totally unaffected by noise. For a single qubit, specific measures of coherence are found to freeze under different conditions, with no general agreement between them. Conversely, for an N-qubit system with even N, we identify universal conditions in terms of initial states and local incoherent channels such that all bona fide distance-based coherence monotones are left invariant during the entire evolution. This finding also provides an insightful physical interpretation for the freezing phenomenon of quantum correlations beyond entanglement. We further obtain analytical results for distance-based measures of coherence in two-qubit states with maximally mixed marginals. Introduction.-The coherent superposition of states stands as one of the characteristic features that mark the departure of quantum mechanics from the classical realm, if not the most essential one [1]. Quantum coherence constitutes a powerful resource for quantum metrology [2,3] and entanglement creation [4,5] and is at the root of a number of intriguing phenomena of wide-ranging impact in quantum optics [6-9], quantum information [10], solidstate physics [11,12], and thermodynamics [13][14][15][16][17][18]. In recent years, research on the presence and functional role of quantum coherence in biological systems has also attracted considerable interest [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].Despite the fundamental importance of quantum coherence, only very recently have relevant first steps been achieved towards developing a rigorous theory of coherence as a physical resource [36][37][38] and necessary constraints have been put forward to assess valid quantifiers of coherence [36,39]. A number of coherence measures have been proposed and investigated, such as the l 1 norm and relative entropy of coherence [36] and the skew information [40,41]. Attempts to quantify coherence via a distancebased approach, which has been fruitfully adopted for entanglement and other correlations [42][43][44][45][46][47][48][49][50][51][52], have revealed some subtleties [53].A lesson learned from natural sciences is that coherencebased effects can flourish and persist at significant time scales under suitable exposure to decohering environments. Recent evidence suggests that a fruitful interplay between long-lived quantum coherence and tailored noise may be in fact crucial to enhance certain biological processes, such as light harvesting [27,28,30,31]. This surprising cooperation between traditionally competing phenomena provides an inspiration to explore other physical contexts, such as quantum information science, in order to look for general conditions under which coherence can be sustained in the

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confidence: 99%

Frozen Quantum Coherence

2015

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“…In particular, it measures the usefulness of the system as a reference frame under a superselection rule forbidding the preparation of coherent states in the H eigenbasis [2]. Further studies bridged the gap between these recent theoretical findings and the experimental implementation of quantum information processing, by providing a strategy to measure the asymmetry of an arbitrary quantum state in the laboratory with the current technology [8] (for coherence witnesses, see [20][21][22]). These results paved the way for investigating the link between coherence and quantum properties of multipartite systems.…”

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confidence: 99%

Witnessing Multipartite Entanglement by Detecting Asymmetry

Girolami

Yadin

2017

Entropy

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Abstract:The characterization of quantum coherence in the context of quantum information theory and its interplay with quantum correlations is currently subject of intense study. Coherence in a Hamiltonian eigenbasis yields asymmetry, the ability of a quantum system to break a dynamical symmetry generated by the Hamiltonian. We here propose an experimental strategy to witness multipartite entanglement in many-body systems by evaluating the asymmetry with respect to an additive Hamiltonian. We test our scheme by simulating asymmetry and entanglement detection in a three-qubit Greenberger-Horne-Zeilinger (GHZ) diagonal state.

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“…It is at the root of a number of intriguing phenomena of wideranging impact in quantum optics [31][32][33], where decoherence due to the interaction with an environment is a crucial issue that is of fundamental interest. Quantum coherence which can also been understood via the theory of physical resource [34,35] has attracted increasing interests in many aspects [36][37][38][39][40] such as hot systems [41], many-body systems [42,43], biological system [34,[44][45][46], low-temperature thermodynamics [39,47,48], solid-state physics [49], optimization of squeezed light [50] and so on. In particular, one of the intriguing aspects of quantum coherence is that the atomic coherence has the ability to enhance the efficiencies of nonlinear optical processes [51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Optimal Photon Blockade on the Maximal Atomic Coherence

Zhang

2016

Int J Theor Phys

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There is generally no obvious evidence in any direct relation between photon blockade and atomic coherence.Here instead of only illustrating the photon statistics, we show an interesting relation between the steady-state photon blockade and the atomic coherence by designing a weakly driven cavity QED system with a two-level atom trapped. It is shown for the first time that the maximal atomic coherence has a perfect correspondence with the optimal photon blockade. The negative effects of the strong dissipations on photon statistics, atomic coherence and their correspondence are also addressed. The numerical simulation is also given to support all of our results.

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Witnessing quantum coherence in the presence of noise

Cited by 33 publications

References 37 publications

Frozen Quantum Coherence

Frozen Quantum Coherence

Witnessing Multipartite Entanglement by Detecting Asymmetry

Optimal Photon Blockade on the Maximal Atomic Coherence

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