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@inproceedings{bib_Emer_2025, AUTHOR = {Anand, Vishal and Maity, Ananda G and Mitra, Subhadip and Bhattacharya, Samyadeb }, TITLE = {Emergent non Markovianity and dynamical quantification of the quantum switch}, BOOKTITLE = {Physical Review A}. YEAR = {2025}}

We investigate the dynamical aspects of the quantum switch and find a particular form of quantum memory emerging out of the switch action. We first analyze the loss of information in a general quantum evolution subjected to a quantum switch and propose a measure to quantify the switch-induced memory. We then derive an uncertainty relation between information loss and switch-induced memory. We explicitly consider the example of depolarizing dynamics and show how it is affected by the action of a quantum switch. For a more detailed analysis, we consider both the control qubit and the final measurement on the control qubit as noisy and investigate the said uncertainty relation. Further, while deriving the Lindblad-type dynamics for the reduced operation of the switch action, we identify that the switch-induced memory actually leads to the emergence of non-Markovianity. Interestingly, we demonstrate that the emergent non-Markovianity can be explicitly attributed to the switch operation by comparing it with other standard measures of non-Markovianity. Our investigation thus paves the way forward to understanding the quantum switch as an emerging non-Markovian quantum memory.

@inproceedings{bib_Unra_2025, AUTHOR = {Harshal, Pradhan Shreyas and Bhattacharya, Samyadeb and Mitra, Subhadip and Anand, Vishal and Soufy, Hadi Mohammed and Chattopadhyay, Rik }, TITLE = {Unraveling the non-Markovian spin-boson model and quantum quasi-Otto cycle}, BOOKTITLE = {Physical Review A}. YEAR = {2025}}

We use the spin-boson model to describe the dynamics of a two-level atom interacting with Fabry-Pérot cavity modes. We solve the Schrödinger equation for the system-bath model without the Born-Markov approximation to derive the non-Markovian reduced dynamics of the qubit. We further construct an exact Lindblad-type master equation for it. Similar to the quantum Otto cycle, we construct a non-Markovian quasicyclic process based on the atom-cavity interactions, which we call the quasi-Otto cycle. For judicious choices of input state and parameters, the quasicycle can be more efficient as a quantum engine than the Otto cycle. We also show that if the quasicycle is repeated multiple times, the efficiency of the quasi-Otto engine asymptotically approaches that of the Otto engine.

@inproceedings{bib_Expl_2025, AUTHOR = {Basu, Ritam and Chakraborty, Anish and Badhani, Himanshu and Alimuddin, Mir and Bhattacharya, Samyadeb }, TITLE = {Exploring non-Markovianity in ergodic channels: Measuring memory retention through ergotropy}, BOOKTITLE = {Physical Review A}. YEAR = {2025}}

In this work, we introduce and characterize a broad class of quantum operations with a unique fixed point, termed quantum ergodic channels. We derive Lindblad-type master equations for these channels in arbitrary finite dimensions and analyze their non-Markovian dynamics using established measures. When the fixed point is a passive state, the channels exhibit ergotropy dynamics with notable thermodynamic implications. Specifically, under Markovian processes, ergotropy (a measure of the extractable work from a system under unitary evolution) monotonically decreases. However, in non-Markovian dynamics, ergotropy fluctuates, leading to a backflow effect that highlights memory-induced resource recovery. Our findings suggest that this ergotropy backflow could serve as an operationally meaningful indicator of non-Markovianity, offering new perspectives on the interplay between memory effects and thermodynamic behavior in open quantum systems. This study enhances the theoretical framework for understanding energy dynamics under ergodic channels and highlights new avenues for exploring the implications of memory effects in quantum batteries.

@inproceedings{bib_Usin_2025, AUTHOR = {Srivastava, Suryansh and Pati, Arun Kumar and Chakrabarty, Indranil and Bhattacharya, Samyadeb }, TITLE = {Using Quantum Switches to Mitigate Noise in Grover’s Search Algorithm}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2025}}

@inproceedings{bib_Acti_2024, AUTHOR = {Maity, Ananda and Bhattacharya, Samyadeb }, TITLE = {Activating information backflow with the assistance of quantum SWITCH}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2024}}

There are certain dynamics while being non-Markovian, do never exhibit information backflow. We show that if two such dynamical maps are considered in a scenario where the order of application of these two dynamical maps are not definite, the effective channel can manifest information backflow. In particular, we use quantum SWITCH to activate such a channel. In contrast, activation of those channels are not possible even if one uses many copies of such channels in series or in parallel action. We then investigate the dynamics behind the quantum SWITCH experiment and find out that after the action of quantum SWITCH both the CP (Complete Positive)- divisibility and P (Positive)- divisibility of the channel breaks down, along with the activation of information backflow. Our study elucidate the advantage of quantum SWITCH by investigating its dynamical behavior.

@inproceedings{bib_Rela_2024, AUTHOR = {Mitra, Arindam and Saha, Debashis and Bhattacharya, Samyadeb and Majumdar, A. S. }, TITLE = {Relating completely positive divisibility of dynamical maps with compatibility of channels}, BOOKTITLE = {Physical Review A}. YEAR = {2024}}

The role of completely positive–indivisibility (CP-indivisibility) and incompatibility as valuable resources for various information-theoretic tasks is widely acknowledged. This study delves into the intricate relationship between CP-divisibility and channel compatibility. Our investigation focuses on the behavior of incompatibility robustness of quantum channels for a pair of generic dynamical maps. We show that the incompatibility robustness of channels is monotonically nonincreasing for a pair of generic CP-divisible dynamical maps. Further, our explicit study of the behavior of incompatibility robustness with time for some specific dynamical maps reveals nonmonotonic behavior in the CP-indivisible regime. Additionally, we propose a measure of CP-indivisibility based on the incompatibility robustness of quantum channels. Our investigation provides valuable insights into the nature of quantum dynamical maps and their relevance in information-theoretic applications.

@inproceedings{bib_Inte_2024, AUTHOR = {Mukherjee, Saheli and Mallick, Bivas and Sravani, Yanamandra and Bhattacharya, Samyadeb and Maity, Ananda G }, TITLE = {Interplay between the Hilbert space dimension of the control system and the memory induced by quantum SWITCH}, BOOKTITLE = {Physical Review A}. YEAR = {2024}}

@inproceedings{bib_Quan_2024, AUTHOR = {Srinidhi, P V and Chakrabarty, Indranil and Bhattacharya, Samyadeb and Ganguly, Nirman }, TITLE = {Quantum channels that destroy negative conditional entropy}, BOOKTITLE = {Physical Review A}. YEAR = {2024}}

Counter-intuitive to classical notions, quantum conditional entropy can be negative, playing a pivotal role in information-processing tasks. This article delves deeply into quantum channels, em- phasizing negative conditional entropy breaking channels (NCEB) and introducing negative condi- tional entropy annihilating channels (NCEA). We characterize these channels from both topological and information-theoretic perspectives, examining their properties when combined serially and in parallel. Our exploration extends to complimentary channels associated with NCEB, leading to the introduction of information-leaking channels. Utilizing the parameters of the standard depolarizing channel, we provide tangible examples and further characterization. We demonstrate the relation- ship of NCEB and NCEA with newly introduced channels like coherent information breaking (CIB) and mutual information breaking (MIB), along with standard channels like zero capacity channels. Preservation of quantum resources is an integral constituent of quantum information theory. Rec- ognizing this, we lay prescriptions to detect channels that do not break the negativity of conditional entropy, ensuring the conservation of this quantum resource

@inproceedings{bib_Brea_2024, AUTHOR = {Yanamandra, Sravani and Srinidhi, P V and Bhattacharya, Samyadeb and Chakrabarty, Indranil and Goswami, Suchetana }, TITLE = {Breaking absolute separability with quantum switch}, BOOKTITLE = {Quantum Information Processing}. YEAR = {2024}}

Absolute separable (AS) quantum states are those states from which it is impossible to create entanglement, even under global unitary operations. It is known from the resource theory of non- absolute separability that the set of absolute separable states forms a convex and compact set, and global unitaries are free operations. We show that the action of a quantum switch controlled by an ancilla qubit over the global unitaries can break this robustness of AS states and produce ordinary separable states. First, we consider bipartite qubit systems and find the effect of quantum switch starting from the states sitting on the boundary of the set of absolute separable states. As particular examples, we illustrate what happens to modified Werner states and Bell diagonal (BD) states. For the Bell diagonal states, we provide the structure for the set of AS BD states and show how the structure changes under the influence of a switch. Further, we consider numerical generalization of the global unitary operations and show that it is always possible to take AS states out of the convex set under switching operations. We also generalized our results in higher dimensions.

@inproceedings{bib_Emer_2023, AUTHOR = {Anand, Vishal and Maity, Ananda G. and Mitra, Subhadip and Bhattacharya, Samyadeb }, TITLE = {Emergent non-Markovianity and dynamical quantification of the quantum switch}, BOOKTITLE = {Physical Review A}. YEAR = {2023}}

We investigate the dynamical aspects of the quantum switch and find a particular form of quantum memory emerging out of the switch action. We first analyse the loss of information in a general quantum evolution subjected to a quantum switch and propose a measure to quantify the switch-induced memory. We then derive an uncertainty relation between information loss and switch-induced memory. We explicitly consider the example of depolarising dynamics and show how it is affected by the action of a quantum switch. For a more detailed analysis, we consider both the control qubit and the final measurement on the control qubit as noisy and investigate the said uncertainty relation. Further, while deriving the Lindblad-type dynamics for the reduced operation of the switch action, we identify that the switch-induced memory actually leads to the emergence of non-Markovianity. Interestingly, we demonstrate that the emergent non-Markovianity can be explicitly attributed to the switch operation by comparing it with other standard measures of non-Markovianity. Our investigation thus paves the way forward to understanding the quantum switch as an emerging non-Markovian quantum memory.

@inproceedings{bib_Non-_2023, AUTHOR = {CHANDUKA, SOURAV and Bhattacharya, Bihalan and MUNDRA, ROUNAK and Bhattacharya, Samyadeb and Chakrabarty, Indranil }, TITLE = {Non-Markovianity and entanglement detection}, BOOKTITLE = {International Journal of Quantum Information}. YEAR = {2023}}

We have established a novel method to detect non-Markovian indivisible quantum channels using structural physical approximation. We have shown that this method can be used to detect eternal non -Markovian operations. We have further established that harnessing eternal non-Markovianity, we can device a protocol to detect quantum entanglement.

@inproceedings{bib_Dete_2022, AUTHOR = {Chimalgi, Vaibhav and Bhattacharya, Bihalan and Goswami, Suchetana and Bhattacharya, Samyadeb }, TITLE = {Detecting entanglement harnessing Lindblad structure}, BOOKTITLE = {Physica Scripta}. YEAR = {2022}}

The problem of entanglement detection is a long standing problem in quantum information theory. One of the primary procedures of detecting entanglement is to find the suitable positive but noncompletely positive maps. Here we try to give a generic prescription to construct a positive map that can be useful for such scenarios. We study a class of positive maps arising from Lindblad structures. We show that two famous positive maps viz. transposition and Choi map can be obtained as a special case of a class of positive maps having Lindblad structure. Generalizing the transposition map to a one parameter family we have used it to detect genuine multipartite entanglement. Finally being motivated by the negativity of entanglement, we have defined a similar measure for genuine multipartite entanglement.

@inproceedings{bib_Dyna_2022, AUTHOR = {Tiwari, Devvrat and Datta, Shounak and Bhattacharya, Samyadeb and Banerjee, Subhashish }, TITLE = {Dynamics of two central spins immersed in spin baths}, BOOKTITLE = {Physical Review A}. YEAR = {2022}}

In this article we derive the exact dynamics of a two-qubit (spin 1/2) system interacting centrally with separate spin baths composed of qubits in a thermal state. Furthermore, each spin of the bath is coupled to every other spin of the same bath. The corresponding dynamical map is constructed. It is used to analyze the non-Markovian nature of the two qubit central spin dynamics. We further observe the evolution of quantum correlations like entanglement and discord under the influence of the environmental interaction. Moreover, we demonstrate the comparison between this exact two-qubit dynamics and the locally acting central spin model in a spin bath. This work is a stepping stone towards the realization of non-Markovian heat engines and other quantum thermal devices.

@inproceedings{bib_Dyna_2022, AUTHOR = {Tiwari, Devvrat and Datta, Shounak and Bhattacharya, Samyadeb and Banerjee, Subhashish }, TITLE = {Dynamics of two qubit central spin under fermionic environment}, BOOKTITLE = {Technical Report}. YEAR = {2022}}

In this article we derive the exact dynamics of a two qubit (spin 1/2) system interacting centrally with separate fermionic baths composed of qubits in thermal state. Further, each spin of a bath is coupled to every other spin of the same bath. The corresponding dynamical map is constructed. It is used to analyse the non-Markovian nature of the two qubit central spin dynamics. We further observe the evolution of quantum correlations like entanglement and discord under the influence of the environmental interaction. Moreover, we demonstrate the comparison between this exact two qubit dynamics and the locally acting fermionic central spin model. This work is a stepping stone towards the realization of non-Markovian heat engines and other quantum thermal devices.

@inproceedings{bib_Dete_2022, AUTHOR = {Vaishy, Ankit Shambhunath and Mitra, Subhadip and Bhattacharya, Samyadeb }, TITLE = {Detecting genuine multipartite entanglement in three-qubit systems with eternal non-Markovianity}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2022}}

We devise a novel protocol to detect genuinely multipartite entangled states by harnessing quantum non-Markovian operations. We utilize a particular type of non-Markovianity known as the eternal non-Markovianity to construct a non-complete positive map to filter out the bi-separable states and detect genuine multipartite entanglement. We further propose a witness operator to detect gen- uinely multipartite entangled states experimentally based on this theory. Our study sheds light on a hitherto unexplored connection between entanglement theory and quantum non-Markovianity.

@inproceedings{bib_Acti_2022, AUTHOR = {Maity, Ananda G and Bhattacharya, Samyadeb }, TITLE = {Activating hidden non-Markovianity with the assistance of quantum SWITCH}, BOOKTITLE = {Technical Report}. YEAR = {2022}}

here are certain dynamics which although are non-Markovian but never show information backflow. We show that if two such dynamical maps are considered in a scenario where the order of application of these two dynamical maps are not definite, then the effective channel can manifest information backflow. In particular, we use quantum SWITCH to activate such channels. In contrast, those channels can never be activated even if we use many copy of such channels in series or parallel action. We then investigate the actual cause and dynamics behind the quantum SWITCH experiment and find out that after the action of quantum SWITCH both the CP (Complete Positive)- divisiblity and P (Positive)- divisibility of the channel breaks down, triggering the information backflow. Our investigations shed new light on the fundamental cause of the advantages of quantum SWITCH

@inproceedings{bib_Conv_2021, AUTHOR = {Bhattacharya, Bihalan and Bhattacharya, Samyadeb }, TITLE = {Convex geometry of Markovian Lindblad dynamics and witnessing non-Markovianity}, BOOKTITLE = {Quantum Information Processing}. YEAR = {2021}}

We develop a theory of linear witnesses for detecting non-Markovianity, based on the geometric structure of the set of Choi states for all Markovian evolutions having Lindblad-type generators. We show that the set of all such Markovian Choi states form a convex and compact set under the small time interval approximation. Invoking geometric Hahn–Banach theorem, we construct linear witnesses to separate a given non-Markovian Choi state from the set of Markovian Choi states. We present examples of such witnesses for dephasing channel and Pauli channel in case of qubits. Furthermore, we have devised another method of detection NM of various qubit channels, by using projective measurements in the Bell basis. This can be done without the knowledge of what specific kind of channel we are dealing with. This gives us a huge operational advantage for NM detection. We further investigate the geometric structure of the Markovian Choi states to find that they do not form a polytope. This presents a platform to consider nonlinear improvement of non-Markovianity witnesses.

@inproceedings{bib_Near_2021, AUTHOR = {Das, Sreetama and Roy, Sudipto Singha and Bhattacharya, Samyadeb and Sen, Ujjwal }, TITLE = {Nearly Markovian maps and entanglement-based bound on corresponding non-Markovianity}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2021}}

We identify a set of dynamical maps of open quantum system, and refer to them as 'epsilon-Markovian' maps. It is constituted of maps which, in a higher dimensional system–environment Hilbert space, possibly violate Born approximation but only a 'little'. We characterize the 'epsilon-nonmarkovianity' of a general dynamical map by the minimum distance of that map from the set of epsilon-Markovian maps. We analytically derive an inequality which gives a bound on the epsilon-nonmarkovianity of the dynamical map, in terms of an entanglement-like resource generated between the system and its 'immediate' environment. In the special case of a vanishing epsilon, this inequality gives a relation between the epsilon-nonmarkovianity of the reduced dynamical map on the system and the entanglement generated between the system and its immediate environment. We numerically investigate the behavior of the similar distant based measures of non-Markovianity for classes of amplitude damping and phase damping channels.

@inproceedings{bib_Revi_2021, AUTHOR = {Bhattacharya, Samyadeb and Banerjee, Subhashish }, TITLE = {Revisiting the Quantum Open System Dynamics of Central Spin Model}, BOOKTITLE = {Quanta}. YEAR = {2021}}

n this work, we revisit the theory of open quantum systems from the perspective of fermionic baths. Specifically, we concentrate on the dynamics of a central spin half particle interacting with a spin bath. We have calculated the exact reduced dynamics of the central spin and constructed the Kraus operators in relation to that. Further, the exact Lindblad type canonical master equation corresponding to the reduced dynamics is constructed. We have also briefly touched upon the aspect of non-Markovianity from the backdrop of the reduced dynamics of the central spin. Quanta 2021; 10: 55–64

@inproceedings{bib_Dete_2021, AUTHOR = {Vaishy, Ankit Shambhunath and Mitra, Subhadip and Bhattacharya, Samyadeb }, TITLE = {Detecting genuine multipartite entanglement by eternal non-Markovianity}, BOOKTITLE = {Technical Report}. YEAR = {2021}}

Entanglement is a fascinating feature, typical and ubiquitous to the science of quantum information and computation. Over the last few decades, we have seen entanglement, or more precisely bipartite entanglement, playing an unparalleled role in various quantum information-theoretic tasks [1–3]. Multipartite entanglement comes with an even richer structure and a whole new set of features providing information processing advantages in quantum communication, simulation, or metrology. It is therefore essential to construct methods to identify genuinely multipartite entangled states [4–6]. However, detecting entanglement of an arbitrary quantum state is a problem of significant complexity [7, 8]. Thus, witnessing entanglement by using versatile experimentally feasible tools [9–18] is a challenging task. In the case of multipartite entanglement, the challenge enhances significantly and demands greater interest from the scientific community. In this paper, we propose a protocol to detect multipartite entanglement by utilizing the well-known phenomenon of non-Markovianity in open quantum systems [19, 20] and the theory of positive maps. The positive maps that are not completely positive can detect bipartite entanglement quite effectively, Partial Transposition [21] being a well-known example. Unfortunately, this technique cannot be directly extended to the case of multipartite entanglement, where diverse separability structures complicate the detection problem. Although semi-definite programming can be used to construct witnesses to certify genuine multipartite entangle

@inproceedings{bib_Gene_2021, AUTHOR = {Bhattacharya, Bihalan and Goswami, Suchetana and MUNDRA, ROUNAK and NirmanGanguly, and Chakrabarty, Indranil and Bhattacharya, Samyadeb and Majumdar, A. S. }, TITLE = {Generating and detecting bound entanglement in two-qutrits using a family of indecomposable positive maps}, BOOKTITLE = {Journal of Physics Communications}. YEAR = {2021}}

The problem of bound entanglement detection is a challenging aspect of quantum information theory for higher dimensional systems. Here, we propose an indecomposable positive map for two-qutrit systems, which is shown to generate a class of positive partial transposed (PPT) states. A corresponding witness operator is constructed and shown to be weakly optimal and locally implementable. Further, we perform a structural physical approximation of the indecomposable map to make it a completely positive one, and find a new PPT entangled state which is not detectable by certain other well-known entanglement detection criteria.

@inproceedings{bib_Conv_2020, AUTHOR = {Bhattacharya, Samyadeb and Bhattacharya, Bihalan and Miajumdar, A S }, TITLE = {Convex resource theory of non-Markovianity}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2020}}

We establish a convex resource theory of non-Markovianity inducing information backflow under the constraint of small time intervals within the temporal evolution. We identify the free operations and a generalized bona-fide measure of non-Markovian information backflow. The framework satisfies the basic properties of a consistent resource theory. The proposed resource quantifier is lower bounded by the optimization free Rivas–Huelga–Plenio (RHP) measure of non-Markovianity. We next define the robustness of non-Markovianity and show that it can directly linked with the RHP measure of non-Markovianity through a lower bound. This enables a physical interpretation of the RHP measure. We further relate robustness of non-Markovianity with the quantum capacity of dephasing channels.

@inproceedings{bib_Wave_2020, AUTHOR = {Das, Sreetama and Mukhopadhyay, Chiranjib and Singha, Sudipto and Bhattacharya, Samyadeb and Sen(De), Aditi and Sen, Ujjwal }, TITLE = {Wave-particle duality employing quantum coherence in superposition with non-orthogonal pointers}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2020}}

We propose the notion of quantum coherence for superpositions over states which are not necessarily mutually orthogonal. This anticipatedly leads to a resource theory of non-orthogonal coherence. We characterize free states and free operations in this theory, and connect the latter with free operations in the resource theory of quantum coherence for orthogonal bases. We show that the concept of non-orthogonal coherence naturally furnishes us with a wave-particle duality in quantum double-slit experiments where the channels beyond the slits are leaky between them. Furthermore, we demonstrate existence of a unique maximally coherent qubit state corresponding to any given purity. In addition, and in contradistinction with the case of orthogonal bases, there appears a non-trivial minimally coherent qubit state for a given purity. We also study the behavior of quantum coherence for some typical configurations of …

@inproceedings{bib_Dete_2020, AUTHOR = {Maity, Ananda G. and Bhattacharya, Samyadeb and Majumdar, A. S. }, TITLE = {Detecting non-Markovianity via uncertainty relations}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2020}}

We present a formalism for detection of non-Markovianity (NM) through uncertainty relations. We show that when there is an information back-flow to the system from its environment through CP-divisibility breaking, the Choi-states corresponding to the reduced system evolution contain at least one negative eigenvalue. The consequent break down of uncertainty relations for such states can be used to witness non-Markovian dynamics. We present some relevant examples of the phenomenon for qubit channels. We further prove that square of the variance of a suitable Hermitian operator can act as a non-linear witness of NM. We finally show that NM is necessary in order to decrease the uncertainty of the states undergoing unital dynamics for qubits. This provides another method of certifying NM.

@inproceedings{bib_Ther_2020, AUTHOR = {Bhattacharya, Samyadeb and Bhattacharya, Bihalan and Majumdar, A. S. }, TITLE = {Thermodynamic utility of Non-Markovianity from the perspective of resource interconversion}, BOOKTITLE = {Journal of Physics A: Mathematical and Theoretical}. YEAR = {2020}}

We establish a connection between non-Markovianity and negative entropy production rate for various classes of quantum operations. We analyse several aspects of unital and thermal operations in connection with resource theories of purity and thermodynamics. We fully characterize Lindblad operators corresponding to unital operations. We also characterize the Lindblad dynamics for a large class of thermal operations. We next generalize the definition of the entropy production rate for the non-equilibrium case to connect it with the rate of change of free energy of the system, and establish complementary relations between non-Markovianity and maximum loss of free energy. We naturally conclude that non-Markovianity in terms of divisibility breaking is a necessary resource for the backflow of other resources like purity or free energy under the corresponding allowed operations.

@inproceedings{bib_Almo_2019, AUTHOR = {Das, Sreetama and Roy, Sudipto Singha and Bhattacharya, Samyadeb and Sen, Ujjwal }, TITLE = {Almost Markovian maps and entanglement-based bound on corresponding non-Markovianity}, BOOKTITLE = {Technical Report}. YEAR = {2019}}

We identify a set of dynamical maps of open quantum system, and refer to them as" -Markovian" maps. It is constituted of maps that possibly violate Markovianity but only a" little". We characterize the" -nonmarkovianity" of a general dynamical map by the minimum distance of that map from the set of -Markovian maps. We analytically derive an inequality which gives a bound on the -nonmarkovianity of the dynamical map, in terms of an entanglement-like resource generated between the system and its" immediate" environment. In the special case of a vanishing , this inequality gives a relation between the non-Markovianity of the reduced dynamical map on the system and the entanglement generated between the system and its immediate environment. We investigate the behavior of the measures for classes of amplitude damping and phase damping channels.

@inproceedings{bib_Evol_2018, AUTHOR = {Bhattacharya, Samyadeb and Pati, Arun Kumar and Banerjee, Subhashish }, TITLE = {Evolution of coherence and non-classicality under global environmental interaction}, BOOKTITLE = {Quantum Information Processing}. YEAR = {2018}}

A master equation has been constructed for a global system–bath interaction in the both absence and 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 the presence of the above-mentioned interactions. We show that the global part of the system–bath interaction compensates for the decoherence, resulting in slowdown of coherence and entanglement decay. For an appropriately defined limiting case, both coherence and entanglement show freezing behavior 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 …