Semiconductor Quantum Computing

Quantum confined electronic and nuclear spins in semiconductors are promising candidates for a scalable quantum information processor. The coherence times of such qubits in the form of quantum dots and dopants are exceptionally long in silicon. The possibility to address such qubits with electrostatic gates through quantum engineering of electronic wavefunctions may result in an analogous information processing platform as present day computers. I am exploring this new regime of electronics through advanced quantum electronic modeling and simulations. My work focuses on sensitive calibration of the methods with experimental data so that a quantitatively accurate design toolset can be offered to this community.

Gate defined quantum dot qubit in a SiGe/Si device with the electronic wavefunction sampling the atomic disorder at the interface.

STM Electronics

STM lithography has enabled precision placement of single dopants in silicon with lattice unit accuracy. Various functional elements of low-temperature electronics have been demonstrated in an in-plane geometry. Such elements include delta-doped leads and gates, single electron transistors, few-atom quantum dots, and atomic spin qubits. My modeling aims to understand and explore the potential of this atomically precise fabrication technology for functional quantum devices.

An in-plane atomically precise device from Sci. Adv. Vol. 4, no. 7, eaaq1459 (2018).

2D Materials

Emerging 2D materials have unconventional bandstructure and spin, orbital and valley effects that can potentially be harnessed for novel electronic devices. The properties of 2D materials can be tuned by a variety of intrinsic and extrinsic factors that offer the opportunity to engineer designer materials. We employ density functional theory, atomistic tight-binding method, and non-equilibrium Green's function techniques to explore this new class of materials.

Energy Efficient Electronics

Steep transistors offer an energy-efficient solution to the power dissipation problem in present day electronics. These transistors switch with a sub-threshold swing less than the Boltzmann limit. We investigate the design principles of steep transistors with atomistic quantum transport simulations. We have proposed several new designs for tunnel field effect transistors that can simultaneously scale in both dimension and supply voltage requirement, while maintaining large drive currents and steep switching slopes.

Quantum Electronic Simulation Methods

We perform advanced simulation method and software development to solve the simulation challenges for quantum electronics. Recent highlights of our work includes the atomistic configuration interaction technique (FCI), spin-lattice relaxation time calculations, and large-scale finite-element quantum electrostatics simulations. Such techniques are applied to study how various degrees of freedom interact with each other, such as electron-electron, spin-spin, spin-phonon interactions from first principles.