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 $2\times N$ 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