# RSPE Seminar

## Readout and control techniques for GaAs spin qubits

**James Colless**

**Monday 11 January 2016 11am–12pm**

**Link Seminar Room**

From Quantum Devices to Quantum Machines

Quantum computing, the use of quantum phenomena to process information, has begun the long journey from hypothetical possibility to real-world applications. In the same way that the theoretical development of quantum mechanics fundamentally changed the way in which we *understand* the universe, quantum computing offers the potential

to revolutionize the way in which we are able to *interact* with it. In particular, this counter-intuitive nanoscale world of superposition and entanglement may allow previously intractable computational problems to be solved efficiently.

The fundamental building blocks of a quantum information processor are isolated quantum mechanical two-level systems known as quantum bits or ‘qubits'. Ideally such systems are easy to manipulate while being decoupled from noise in their local environment - goals that are often contradictory. In order to outperform their classical cousins at meaningful tasks quantum computers will conservatively require the control of thousands to millions of qubits. While this is still orders of magnitude less than the billions of transistors on a modern microprocessor, it is still far beyond what is currently possible.

This talk explores the complexity of scaling quantum processors and discusses new techniques and hardware developed to meet these challenges. In particular new methods of readout are developed that allow the dispersive sensing of single-electrons using integrated sensors and the capability to read out multiple qubits simultaneously. A scalable control scheme is also demonstrated allowing large numbers of qubits to be manipulated with a small number of input signals.