Abstract: Logical qubits offer new opportunities to improve the speed or fidelity of quantum gate operations. In this talk I will describe experimental and theoretical efforts to develop a logical qubit formed of three electrons in a silicon double quantum dot.  We call this device a quantum dot hybrid qubit because of the ease in transforming between the spin and charge sectors during qubit operation.  An important feature of the hybrid qubit is the ability to perform fast (GHz) rotations around both the x and z axes of the Bloch sphere.  I will show that that the fidelity of single-qubit gate operations in this device approaches the error threshold for implementing surface codes for quantum error correction.

About the Speaker:  Mark Friesen received his PhD in theoretical condensed matter physics from the University of Minnesota-Minneapolis in 1995.  He was a postdoc at Purdue University and at University of Wisconsin-Madison.  He is currently a Senior Scientist at the University of Wisconsin-Madison, focusing on the physics and technology of silicon quantum dots and qubits.