EE&T PhD Student wins 2006 Dean's Award for excellence

Congratulations to S. Ramesh Ekanayake, who is the overall winner in this year’s Dean’s Awards for Excellence in Postgraduate Research (Poster Competition). The prize money is to be used for travel.

Ramesh is supervised by Dr Torsten Lehman and Prof Andrew Dzurak. He provided the following abstract of his research.

The silicon (Si) qubit has been proposed as a test-bed, for scalable solid-state quantum computing, which requires initializing and writing (controlling) [1][2], and measuring (observing). This requires a precise quantum controller and quantum observer integrated with the qubit platform: controller-qubit-observer (CQO) circuits.

My work involves designing the quantum controller for the qubit, and testing it on a silicon qubit chip with a single-electron transistor (SET) that is used for qubit measurement (readout). I have tested SOI RF-CMOS devices at room temperature (300 K), liquid helium temperature (4.2 K), and sub-100 mK in a dilution refrigerator, to study their characteristics at such temperatures and assess the suitability of this technology for the design and fabrication of a controller circuit. This is the first time such devices have been tested at sub-100 mK temperatures. I have already demonstrated the first generation chip at 300 K, 4.2 K, sub-100 mK temperatures, and will be using it in conjunction with a SET to study proximity effects on quantum systems such as qubits. This is important as it is essential to reduce the degree of perturbation introduced by interfacing the controller circuit to the qubit circuit.

This controller chip is possibly the most complex CMOS circuit ever to have been demonstrated at sub-Kelvin temperatures, which is a critical temperature regime for future quantum devices and circuits.