Tomograms for open quantum systems: In(finite) dimensional optical and spin systems

Thapliyal, Kishore; Banerjee, Subhashish; Pathak, Anirban

doi:10.1016/j.aop.2016.01.010

Cited by 27 publications

(23 citation statements)

References 82 publications

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“…Further, quantification of the amount of nonclassicality observed here can be performed using different measures, which may show independent behavior due to dissipation . In general, quantum to classical transition caused due to interaction with the surroundings can be studied under both Markovian and non‐Markovian environments. Interestingly, the nonclassical correlation between system and environment is revealed if the system dynamics cannot be simulated by Hamiltonian ensemble .…”

Section: Discussionmentioning

confidence: 99%

“…Such a state cannot be expressed as a mixture of coherent states and does not possess a classical analogue. In contrast to these states, coherent states are classical, but neither their finite dimensional versions nor their generalized versions are classical . Here, we would like to focus on photon added and subtracted versions of a particular type of generalized coherent state, which is also referred to as the displaced Fock state (DFS).…”

Section: Introductionmentioning

confidence: 99%

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Lower‐ and Higher‐Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States

et al. 2019

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Nonclassical properties of photon added and subtracted displaced Fock states are studied using various witnesses of lower-and higher-order nonclassicality. Compact analytic expressions are obtained for the nonclassicality witnesses. Using those expressions, it is established that these states and the states that can be obtained as their limiting cases (except coherent states) are highly nonclassical as they show the existence of lower-and higher-order antibunching and sub-Poissonian photon statistics, in addition to the nonclassical features revealed through the Mandel Q M parameter, zeros of Q function, Klyshko's criterion, and Agarwal-Tara criterion. Further, some comparison between the nonclassicality of photon added and subtracted displaced Fock states have been performed using witnesses of nonclassicality. This has established that between the two types of non-Gaussianity inducing operations (i.e., photon addition and subtraction) used here, photon addition influences the nonclassical properties more strongly. Further, optical designs for the generation of photon added and subtracted displaced Fock states from squeezed vacuum state have also been proposed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lower‐ and Higher‐Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States

et al. 2019

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“…Specifically, the angular Q function is defined as

0true Q_{θ_{1}} = \int_{0}^{\infty} Q (() β, β^{★}) (||, β) d (||, β)

where the Q function is defined as the projection of the state of interest on the coherent state basis, that is,

Q = \frac{1}{π} false⟨ β false| ρ false| β false⟩

with coherent state parameter

β = | β | exp [ι θ_{1}]

. The relevance of the Q function as witness of nonclassicality and in state tomography is well studied. On top of that, non‐Gaussianity of the PADFS and PSDFS using Q function was recently reported by us …”

Section: Quantum Phase Distribution and Other Phase Propertiesmentioning

confidence: 99%

Quantum Phase Properties of Photon Added and Subtracted Displaced Fock States

et al. 2019

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Quantum phase properties of photon added and subtracted displaced Fock states (and a set of quantum states which can be obtained as the limiting cases of these states) are investigated from a number of perspectives, and it is shown that the quantum phase properties are dependent on the quantum state engineering operations performed. Specifically, the analytic expressions for quantum phase distributions and angular Q distribution as well as measures of quantum phase fluctuation and phase dispersion are obtained. The uniform phase distribution of the initial Fock states is observed to be transformed by the unitary operation (i.e., displacement operator) into non-Gaussian shape, except for the initial vacuum state. It is observed that the phase distribution is symmetric with respect to the phase of the displacement parameter and becomes progressively narrower as its amplitude increases. The non-unitary (photon addition/subtraction) operations make it even narrower in contrast to the Fock parameter, which leads to broadness. The photon subtraction is observed to be a more powerful quantum state engineering tool in comparison to the photon addition. Further, one of the quantum phase fluctuation parameters is found to reveal the existence of antibunching in both the engineered quantum states under consideration. Finally, the relevance of the engineered quantum states in the quantum phase estimation is also discussed, and photon added displaced Fock state is shown to be preferable for the task.

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“…SGAD channels are a generalization of the AD family of channels, which includes the GAD and involves the dissipative interaction with a non-zero temperature bath with non-vanishing squeezing [32]. The squeezing, being a quantum resource, provides an edge over GAD channels, which study a dissipative interaction with a finite temperature bath without squeezing [39,40,41]. Hence, the choice of SGAD channel enables investigations into both non-zero as well as vanishing regimes of squeezing.…”

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confidence: 99%

A comparative study of protocols for secure quantum communication under noisy environment: single-qubit-based protocols versus entangled-state-based protocols

Sharma

Thapliyal

Pathak

et al. 2016

Quantum Inf Process

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The effect of noise on various protocols of secure quantum communication has been studied. Specifically, we have investigated the effect of amplitude damping, phase damping, squeezed generalized amplitude damping, Pauli type as well as various collective noise models on the protocols of quantum key distribution, quantum key agreement, quantum secure direct quantum communication and quantum dialogue. From each type of protocol of secure quantum communication, we have chosen two protocols for our comparative study; one based on single qubit states and the other one on entangled states. The comparative study reported here has revealed that single-qubit-based schemes are generally found to perform better in the presence of amplitude damping, phase damping, squeezed generalized amplitude damping noises, while entanglement-based protocols turn out to be preferable in the presence of collective noises. It is also observed that the effect of noise entirely depends upon the number of rounds of quantum communication involved in a scheme of quantum communication. Further, it is observed that squeezing, a completely quantum mechanical resource present in the squeezed generalized amplitude channel, can be used in a beneficial way as it may yield higher fidelity compared to the corresponding zero squeezing case.

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Tomograms for open quantum systems: In(finite) dimensional optical and spin systems

Cited by 27 publications

References 82 publications

Lower‐ and Higher‐Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States

Lower‐ and Higher‐Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States

Quantum Phase Properties of Photon Added and Subtracted Displaced Fock States

A comparative study of protocols for secure quantum communication under noisy environment: single-qubit-based protocols versus entangled-state-based protocols

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