Quantum Information and Quantum Theory

The theoretical research program in the Department supports a wide range of topics from foundational aspects of quantum theory to quantum information science, non-linear dynamics and Physics Education. Here are some highlights of the research in the area of Quantum Information and Quantum Theory

single electrons


Interference of single electrons

macroscopic realmmacroscopic realm

Interference in the macroscopic realm?

What we are working on:

    • Theoretical techniques (covariance matrix approach) to characterize entanglement in symmetric multi qubit systems.
      • Intrinsic connection between spin squeezing and entanglement in permutation symmetric as well as non-symmetric multiqubit systems.
      • Open system dynamics using Sudarshan’s A and B maps; not completely positive maps and characterization of non-Markovian dynamics.
      • Quantum target detection and quantum reading of digital memory using entangled and non-classical light.
      • Entropic Leggett-Garg inequalities to investigate macrorealism.
      • Uncertainty relations in the classical scenario and connection with symplectic geometry in phase space.
      • Generalized unsharp measurements and quantum features.

Select Publications:

  • Characterizing multiparticle entanglement in symmetric N-qubit states via negativity of covariance matrices, A. R. Usha Devi, R. Prabhu and A. K. Rajagopal, Phys. Rev. Lett. 98, 060501 (2007)
  • Generalized information theoretic measure to discern the quantumness of correlations, A. R. Usha Devi and A. K. Rajagopal, Phys. Rev. Lett. 100, 140502 (2008)
  • Quantum discord and classical correlation can tighten the uncertainty principle in the presence of quantum memory, A. K. Pati, Mark M. Wilde, A. R. Usha Devi, A. K. Rajagopal, Sudha, Physical Review A 86, 042105 (2012)
  • Macrorealism from entropic Leggett-Garg inequalities, A. R. Usha Devi, H. S. Karthik, Sudha and A. K. Rajagopal, Phys. Rev. A 87, 052103 (2013)
  • Quantum reading of digital memory with non-Gaussian entangled light, J. Prabhu Tej, A. R. Usha Devi, A. K. Rajagopal, Phys. Rev. A 87, 052308 (2013)

Usha Devi

Quantum Probability

contextualcontextual observ


M.S. Uma, R. Prabhu and A. R. Usha Devi going over a calculation