Solid-State Quantum Dot Devices for Quantum Computing
Inventors: Mark Eriksson, Mark Friesen, Robert Joynt, Max Lagally, Daniel van der Weide, Paul Rugheimer, Donald Savage
The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a scalable, multilayer semiconductor device that can be used to build a quantum computer.
Over the past 25 years, classical computers have completely transformed the way we live and work. Yet, certain extremely complex tasks, such as sorting very large databases, factoring large numbers (needed for encryption and code-breaking) and modeling quantum mechanical systems (important in drug design) remain unsolvable by today’s computers. Indeed, these problems are so difficult they require a new type of computer altogether – the quantum computer. Quantum computers use quantum particles (e.g., electrons), called qubits, to process information, instead of bits as in classical computing. The key hurdle to overcome with this emerging technology is building a scalable design with enough “memory,” or qubits, for effective computing.
An interdisciplinary team of UW-Madison physicists, engineers and materials scientists has now designed a scalable, multilayer semiconductor device that can be used to build a quantum computer. Fabricated by growing layers of semiconductors and patterning electrostatic gates on the surface, this quantum dot device traps individual electrons in a solid, brings the electrons close to each other, maintains the electrons’ phase coherence and allows manipulation of the electrons’ individual spin states.
- Quantum computing
- Single electron transistors
- Integrated circuits requiring control of individual electrons
- Scalable – design allows formation of a large number of quantum dots in series with appropriate coupling between dots
- Design should provide greater control in manipulating single electrons than previously achieved.
- Quantum dots are optimized to hold single electrons, thus eliminating the need for impurities that bind individual electrons as in some solid-state designs.
- Provides highly sensitive methods for measuring and manipulating individual qubits, thereby meeting the requirements for a successful solid-state computing device
- Detection of individual electron charges may be carried out using low-noise field effect transistors (FETs) – a natural choice for large-scale manufacturing.
- Multiple semiconductor layers can be grown with conventional deposition systems.
- Design should minimize quantum computing errors caused by electron “leakage” from proper orbital states and fluctuations in the number of electrons per dot.