Superconducting circuits based on Josephson junctions have emerged as frontrunners in the world wide effort for Quantum Information Processing. When cooled to a few millikelvin, these nonlinear circuits behave as macroscopic quantum objects - artificial atoms - that can now be used as qubits to build a quantum computer. In the last decade, since the breakthrough of circuit quantum electrodynamics (cQED), where an artificial atom is coupled to a linear resonator, in a configuration analogous to cavity quantum electrodynamics, researchers have successfully demonstrated the strong coupling regime of light-matter interaction. Using this cQED architecture, they demonstrated increasingly long coherence times for the qubits, thereby promising a bright future for these devices in the field of quantum information. Currently several major technology players in the world, such as Google, IBM, Microsoft and Intel have entered the foray and pushed the boundaries of technology in this field. And in most cases, superconducting circuits are very much in a pivotal role.

The Quantum Technologies Laboratory @ IISc plans to study superconducting circuits for applications in quantum information processing, as well as exploring exotic phenomena in atom-photon interactions.

We are interested in Quantum Information Processing with superconducting circuits in particular and solid state circuits in general. These circuits made of Josephson junctions acting as nonlinear inductors can be designed to behave as artificial atoms with tunable frequencies. These artificial atoms with characteristic frequencies in the microwave regime (2 GHz to 12 GHz typically) of the electromagnetic spectrum can be coupled strongly to microwave photons in a cavity through their large dipole moments, thereby easily realising the strong coupling regime of cavity quantum electrodynamics. This field of circuit quantum electrodynamics is relatively young — about fifteen years old now. Our current work also involves coupling these superconducting artificial atoms to propagating phonons on the surface of a piezoelectric substrate to realise the acoustic analogue of quantum optics— quantum acoustics. The field of Quantum acoustics is very young — the first experiments being done at Chalmers in 2014 — and has several experimental challenges to overcome, as well as new frontiers and applications to explore. Another area of interest to us is that of single photon generators and detectors in the microwave regime.