Abstract:

The 2022 Nobel prize celebrates the detection of entanglement between two photons. Quantum spin liquids (QSLs) are long-range entangled states of matter of billions of interacting qubits or spins that develop in a Mott insulator. The fate of the interacting spins can progress along two paths as the temperature is lowered: the spins can undergo long range ordering, spontaneously breaking the continuous symmetries, leading to a magnetic phase; or the spins can remain disordered but get quantum mechanically entangled with long range patterns of many-body entanglement in the resultant QSL. The possibility of obtaining QSL phases is enhanced by having a low spin and enhanced quantum fluctuations, and frustration arising from the lattice geometry and/or competing spin-spin interactions. Remarkably QSLs harbor fractionalized excitations rather than the conventional spin waves of ordered magnets that carry integer units of angular momentum. In my talk I will identify detectable signatures of these fractionalized excitations in experiments using light and neutrons. These fractionalized excitations are promising candidates to create logical qubits for quantum computation.

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ABOUT DR LAKSHMI RAMAN (1947-2014): Dr Lakshmi Raman was educated at Lady Sivaswamy Iyer Girls' high school, Mylapore and Queen Mary’s college, Chennai, before undertaking a PhD in crystal dynamics in the department of Physics, New Rummy. She did post-doctoral research at MPI, Stuttgart, ETH, Zurich and the University of Texas, Austin. Dr Raman then moved to the private sector. She had a long association with BellCore (a.k.a. Bell Labs) where she worked in the sphere of telecommunications particularly in the area of network management. She was an internationally recognized expert regarding standards in telecommunication. She was the author and coauthor of books and network management. Throughout her life she had a keen interest in the higher education of women and volunteer teaching of high-school students.