Investigators

We perform ultra-low temperature electronic measurements, often at high magnetic fields, of devices defined by micro- and nanolithography, and controlled by various electrostatic gates. Materials used for these devices range from conventional semiconductors, such as GaAs, to 2D materials such as graphene or dichalcogenides.

Our research lies at the convergence of condensed matter physics, ultrafast photonics and spectroscopy. It encompasses the development of new and customized femtosecond laser sources and accompanying spectroscopic techniques and employing them in tandem to unravel properties of quantum materials when they are at equilibrium and when they are in excited states. In a long-term scientific goal, we seek to implement photonic manipulation and control of quantum states/phases within solids.

Our research activities centre on the study of the interaction of light with nanostructures leading to highly localized heating and thermal electron and photon emission. Our work involves device design, micro/nanofabrication in the cleanroom, nanostructure growth and deposition, electron and scanning-probe microscopy, building experimental apparatus such as high or ultra-high vacuum systems, electronic characterization and sensitive instrumentation, and working with lasers and optics. We complement our experimental efforts with theory and simulation using methods ranging from continuum modelling to classical molecular dynamics to first-principles, quantum-mechanical techniques such as the Hartree-Fock theory, configuration-interaction, perturbation theory and the density functional theory.

My current interests focus on developing accurate variational approximations for answering key questions that arise in the study of strongly correlated systems: (i) what are the characteristics of the quasiparticle (polaron) that forms when a charge carrier becomes “dressed” by a cloud of excitations such as phonons, magnons, etc.; (ii) what effective interactions arise between such quasiparticles through the exchange of excitations between their clouds; and (iii) what is their combined influence on the properties of the host material. We use these methods to study effective models of materials such as the high-temperature cuprates and iron pnictides, rare-earth nickelates, bismuthates, etc., in a wide region of the parameter space. Such studies supplement numerical exact studies, which are usually rather time-consuming and have limitations in terms of system size, temperature range, etc. Our main focus so far has been on few-particle properties in the extremely underdoped limit of insulators at zero temperature. We are now attempting to expand our expertise to cover finite temperatures and finite particle densities.

Our work is at the intersection of quantum physics, machine learning and chemistry on problems of relevance to quantum materials and quantum technologies, including quantum computing, quantum sensing and quantum algorithms. We are particularly excited about applications of machine learning for solving complex quantum problems and applications of quantum hardware for machine learning.

Our new Quantum Materials Electron Microscopy Centre will have a state of the art electron microscope for atomic imaging and characterization of materials and for carrying out electron energy loss measurements as a function of momentum with ultra-high energy resolution. Research with this latter capability may include measurements of the momentum dependence of the dielectric function of quantum materials, studies of collective excitations in inhomogeneous strongly correlated matter, and studies of the spectrum of confined optical modes in polaritonic media. We are also developing a nanospectroscopy laboratory for conducting optical spectroscopy measurements. This will aid in discovery of new polaritonic materials based on 2D electrides and layered transition metal oxides, and developing means for controlling them by integrating them with quantum materials.

Our group is focused on finding new materials that are at or near a quantum phase transition, where new phases of matter—including novel order—emerges at zero temperature. We carry out measurements of fundamental quantities, such as the transport of charge and heat, and especially their magnetic properties using a combination of lab-based techniques and also neutron scattering facilities. These materials form the basis of a number of different collaborations that leverage the experimental strengths within Blusson QMI.