Priya Sharma

Dr Priya Sharma


Research Fellow in Hybrid Quantum Systems

About

Areas of specialism

superfluid qubit technology, superfluid helium-3, unconventional superconductivity, effects of disorder, quasiclassical theory, anomalous effects, dynamical effects in quantum materials

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Research

Research interests

Publications

P. J. Heikkinen, A. Casey, L. V. Levitin, X. Rojas, A. Vorontsov, P. Sharma, N. Zhelev, J. M. Parpia, J. Saunders (2021)Fragility of surface states in topological superfluid He, In: Nature communications12(1)1574 NATURE PORTFOLIO

Superfluid He-3, with unconventional spin-triplet p-wave pairing, provides a model system for topological superconductors, which have attracted significant interest through potential applications in topologically protected quantum computing. In topological insulators and quantum Hall systems, the surface/edge states, arising from bulk-surface correspondence and the momentum space topology of the band structure, are robust. Here we demonstrate that in topological superfluids and superconductors the surface Andreev bound states, which depend on the momentum space topology of the emergent order parameter, are fragile with respect to the details of surface scattering. We confine superfluid He-3 within a cavity of height D comparable to the Cooper pair diameter xi(0). We precisely determine the superfluid transition temperature T-c and the suppression of the superfluid energy gap, for different scattering conditions tuned in situ, and compare to the predictions of quasiclassical theory. We discover that surface magnetic scattering leads to unexpectedly large suppression of T-c, corresponding to an increased density of low energy bound states.

Priya Sharma (2020)Approach to Solving Quasiclassical Equations with Gauge Invariance, In: Journal of low temperature physics201(1-2)pp. 73-81 Springer Nature

Quasiclassical equations with manifest gauge invariance are discussed in the context of unconventional singlet superconducting states in the static limit. Deviations of the quasiclassical propagator from its equilibrium solutions in the presence of magnetic fields and Hall terms are analysed in terms of a "small" parameter and a formulation developed to first order in "small". A modified quasiclassical propagator is defined to this order that is a solution of a new gauge-invariant Eilenberger-like equation with a normalization condition. A Riccati parametrization with manifest gauge invariance is proposed. Riccati equations are derived to leading order in "small" that are directly applicable to superconducting systems in the presence of magnetic fields.

Additional publications