566 research outputs found
Interrelation of nonclassicality features in higher-dimensional systems through logical operators
Interrelation of different nonclassical correlations with quantum coherence
has been shown in [S. Asthana. New Journal of Physics 24.5 (2022): 053026] for
multiqubit systems through logical qubits. In this work, we generalise that
work to higher dimensional systems. For this, we assume different forms of
logical qudits and logical continuous-variable (cv) systems in terms of their
physical constituent qudits and physical cv systems. Thereafter, we show how
conditions for coherence in logical qudits and logical cv systems themselves
give rise to conditions for nonlocality and entanglement in their physical
constituent qudits and cv systems. As we increase the number of parties in a
logical qudit, conditions for coherence map to those for entanglement and then,
for nonlocality. We illustrate it with the examples of SLK inequality and a
condition for entanglement in continuous-variable systems. Furthermore, with
nonclassicality of logical cv systems, we show that a recently introduced
correlation can also be understood. Finally, we show how a condition for
imaginarity maps to partial-positive transpose criterion in two-qubit systems.
This shows that a single nonclassicality condition detects different types of
nonclassicalities in different physical systems. Thereby, it reflects
interrelations of different nonclassical features of states belonging to
Hilbert spaces of nonidentical dimensions
Relation between nonclassical features through logical qudits
Scalable modern-time fault-tolerant quantum computation and quantum
communication in a network employ a large number of physical qubits. For
example, IBM is reported to have made a 127-qubit quantum computer. Unlike
classical computation, quantum computation employs different types of logical
qubits and qudits in terms of physical multiqubit and multiqudit systems
respectively. Given this, of particular interest to us is to enquire on how
quantum coherence in logical qubits is a manifestation of underlying quantum
correlations in constituent physical multiqubit systems and vice-versa. In a
recent work [Asthana, Sooryansh. New J Phys 24.5 (2022): 053026], we have shown
that there is reciprocity in nonclassical correlations in physical multiqubit
systems and coherence in a single logical qubit system. Subsequently, we have
generalised the framework to higher dimensional quantum systems []. The crux of
this study is that a single nonclassicality condition derived for quantum
coherence in a logical system detects more than one type of nonclassicality in
Hilbert spaces of nonidentical dimensions.Comment: Accepted in QIP 2023 (held in Ghent, Belgium) as a poster
presentatio
Two new records of Plagiothecium from India
Abstract
Govind Wild Life Sanctuary in the Western Himalayas with its diverse vegetation types provides excellent habitats and microclimates for a lush growth of bryophytes. During investigations on the bryophytes of this region Plagiothecium euryphyllum (Cardot et Thér.) Z. Iwats. and P. cavifolium (Brid.) Z. Iwats. have been identified for the first time from India. P. euryphyllum is characterised by bright green to yellowish green plants, irregularly branched, complanate. Central strand developed. Leaves erectopatent, imbricate, ovate oblong, margin entire, acute to acuminate at apex, costa two forked, decurrent with hyaline, rectangular cells. Seta reddish, capsule erect to inclined, while plants of P. cavifolium are yellowish green, glossy, prostrate, irregularly branched, branches julaceous. Leaves appressed to stem, closely imbricate, erectopatent, ovate lanceolate, symmetrical, margin minutely dentate at apex, cells at alar region rectangular costa two short. Seta reddish brown, capsule erect, pyriform. A morpho-taxonomic account of above two taxa is provided
Quantum secure direct communication with SU(2) invariant separable polarisation- OAM states
We propose a quantum secure direct communication protocol using SU (2)-
invariant separable states, identified as separable equivalents of
two-qubit entangled Werner states in [Bharath & Ravishankar, Phys. Rev. A 89,
062110}]. These states can be experimentally realized as incoherent
superpositions of separable polarisation-OAM states.Comment: Accepted for oral presentation in International Conference on Quantum
Computing and Communications held at Bathinda, Punjab, Indi
Layered semiquantum secure communication protocols
In this paper, we harness the potential offered by multidimensional states in
secure communication with only one quantum participant. We propose four
protocols for--(i) layered semi--quantum key distribution, (ii) layered
semi-quantum secret sharing, (iii) integrated layered semi-quantum key
distribution and secret sharing, and, (iv) integrated layered semi-quantum
secure direct communication and key distribution to share secret information in
an arbitrary layered network. All the four protocols allow for simultaneous
distribution of secure information in all the layers of a network, thanks to
multidimensional states.Comment: 13 pages, 2 figure
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