Saptarshi Roy

Saptarshi joined QICi as a postdoc fellow in 2022. He got his bachelor's degree at Jadavpur University , Kolkata, India, in 2014. After that he moved to the Harish Chandra Research Institute, Allahabad, India, where he got his master's degree in physics in 2016 and his PhD in 2022. 

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Research Interests

Presently, I am working on indefinite causal order using the quantum SWITCH. I am investigating these ideas in quantum communication and thermodynamic work extraction. My other areas of interest include the study of communication protocols involving deterministic dense coding networks, multiparty teleportation, and analysis of the performance of teleportation via deviation in fidelity. For continuous variable systems, I have studied nonclassical properties (nonlocality and genuine entanglement) of two- and multi-mode Gaussian and non-Gaussian states of light. I have also investigated equilibrium and dynamical quantum phase transitions in one-dimensional XY-type models using the tools of quantum information theory in the presence of both uniform and alternate transverse magnetic fields. Some finite temperature effects on these models were also investigated. I have also extensively explored multisite quantum correlation in different scenarios including restrictions in their shareability and their role as a resource. 

Selected Publication

S. Roy, A. Bera, S. Mal, A. Sen De, U. Sen
Recycling the resource: Sequential usage of shared state in quantum teleportation with weak measurements
Phys. Lett. A 392, 127143 (2021)

S. Haldar, S. Roy, T. Chanda, A. Sen De
Response of macroscopic and microscopic dynamical quantifiers to the quantum critical region
Phys. Rev. Research 2, 033249 (2020)

S. Roy, A. Ghosal
Rating the performance of noisy teleportation using fluctuations in fidelity
Phys. Rev. A 102, 012428 (2020)

S. Roy, T. Das, A. Sen De
Computable genuine multimode entanglement measure: Gaussian vs. non-Gaussian
Phys. Rev. A 102, 012421 (2020)

S. Haldar, S. Roy, T. Chanda, A. Sen De, U. Sen
Multipartite entanglement at dynamical quantum phase transitions with non-uniformly spaced criticalities
Phys. Rev. B 101, 22430 (2020)

A. Ghosal, D. Das, S. Roy, S. Bandyopadhyay
Fidelity deviation in quantum teleportation with a two-qubit state
J Phys A: Math and Theor 53, 14 (2020)

A. Ghosal, D. Das, S. Roy, S. Bandyopadhyay
Optimal two-qubit states for quantum teleportation vis-à-vis state properties
Phys. Rev. A 101, 012304 (2020)


S. Rethinasamy, S. Roy, T. Chanda, A. Sen De, U. Sen
Universality in Distribution of Monogamy Scores for Random Multiqubit Pure States
Phys. Rev. A 99, 042302 (2019)

S. Roy, T. Chanda, T. Das, D. Sadhukhan, A. Sen De, U. Sen
Phase boundaries in alternating field quantum XY model with Dzyaloshinskii-Moriya interaction: Sustainable entanglement in dynamics
Phys. Rev. B 99, 064422 (2019)

S. Roy, T. Chanda, T. Das, A. Sen De, U. Sen
Response in violation of Bell inequality to imperfect photon addition and subtraction in noisy squeezed states of light
Phys. Rev. A 98, 052131 (2018)

S. Roy, T. Chanda, T. Das, A. Sen De, U. Sen
Deterministic Quantum Dense Coding Networks
Physics Letter A 382, 1709 (2018)

S. Roy, T. Das, A. Kumar, A. Sen De, U. Sen
Activation of Nonmonogamous Multipartite Quantum States
Rev. A 98, 012310 (2018)

S. Roy, T. Das, D. Das, A. Sen De, U. Sen
How efficient is transport of quantum cargo through multiple highways?
Annals of Physics 422, 168281 (2020)

L. Ganesh C. Lakkaraju, S. Ghosh, S. Roy, A. Sen De
Distribution of entanglement with variable range interactions
Phys. Lett. A 418, 127703 (2021)


S. Roy, S. Mal, A. Sen De
Restrictions on shareability of classical correlations for random multipartite quantum states
Phys. Rev. A 103, 052401 (2021)


S. Roy, S. Mal, A. Sen De
Gain in performance of quantum teleportation with uniformity breaking distributions
Phys. Rev. A 105, 022610 (2022)


A. Patra, R. Gupta, S. Roy, Aditi Sen De
Significance of Fidelity Deviation in Continuous Variable Teleportation
Phys. Rev. A 106, 022433 (2022)

Awards

2019:

HRI-INFOSYS Prize for excellence in research in Quantum Information Theory

2014:

 Qualified for Junior Research Fellowship and Lectureship, in Council of Scientific and Industrial Research-National Eligibility Test (CSIR-NET) examination.

2011:

Recipient of the Scholarship for Higher Education under the scheme of the Innovation in Science Pursuit for Inspired Research (INSPIRE) Fellowship Grant from Department of Science and Technology (DST), Government of India.

CV

My CV can be found here.