Exploration and Control of Condensed Matter Qubits

Dramatic theoretical advances in the field of Quantum Information Sciences over the past seven years have led to increasing pressure for physical realization of true quantum devices that can be operated coherently to provide reversible quantum logic. Such devices are required for novel communication and computing schemes exploiting quantum mechanical effects. Although enormous strides have been made in developing algorithms, quantum codes, and powerful cryptographic protocols, experimental implementation still poses some very difficult problems. Much basic science must be performed before we can begin to realize truly scalable quantum computers. We address this challenge with experimental studies to explore the physics of potential qubit systems, and with theoretical investigations of new approaches to minimize decoherence and to provide protocols for robust quantum control and efficient quantum logic.
A main theme of our proposal is to exploit new abilities to fabricate and control matter at increasingly small dimension to help generate new technologies for processing information. Our interdisciplinary group of scientists and engineers, drawn from computer science, chemical physics, and solid state physics, will jointly explore the development of new types of devices that utilize quantum degrees of freedom in solid-state nanostructures to process information.
Our research proposal focuses on three issues for qubit implementation: quantum state measurement and initialization, decoherence, and entanglement. These issues will be explored for a number of condensed matter qubit candidates. Each potential qubit system holds the possibility for significant long-term scalability, provided that the three fundamental issues can be adequately dealt with. Our six PIs will undertake joint theoretical and experimental efforts with multiple collaborations between all group projects. Theoretical work will focus on understanding, controlling, and minimizing decoherence. We shall undertake a systematic development of control procedures that maximize both the efficiency and robustness of quantum logic gates. Experimental work will focus on characterizing qubit states employing electronic and nuclear spins in solids, as well as superconducting flux coherences. Novel condensed matter qubit structures will be synthesized using state-of-the-art nanofabrication techniques, and probed using the unique measurement tools available to the group members. Initial experiments will be aimed at quantum state measurement and initialization, but subsequent goals will involve working to minimize decoherence and to enable controlled quantum logic operations.