Mathematician and Fields Medal winner Michael Freedman leads Microsoft Station Q, which includes an internal team of theorists coupled to four satellite Station Q experimental groups and two satellite Station Q theory teams working in close collaboration.
Station Q Purdue, directed by professor Michael Manfra, is poised to become a leading element of a grand international collaboration spanning engineering, physics and computer science, whose goal is to establish the foundations for a new quantum technology, Michael Freedman said.
"Microsoft is in the quantum game for the long run; we are investing in the scientific and engineering foundations", he stated. "Mike Manfra comes from the world's finest tradition in materials growth - having early training at Bell Labs - but what really makes him stand out is that he is also a transport physicist and truly understands what will happen downstream to the samples he grows. This gives him a rare insight."
Michael Manfra's team has received multimillion-dollar funding for this fundamental research.
"With literally the entire world of individual talent and institutional partners to pick from, Microsoft chose Purdue and these brilliant researchers", stated Purdue President Mitch Daniels. "Thanks to them, when one day ultra fast quantum computing becomes real, Purdue will be a part of that historic moment."
Quantum computing - an advanced architecture for computing that uses the quantum mechanical behaviour of electrons to store and process information - is thought to be able to solve certain classes of problems much faster than a classical computer and open the door to scientific advances that would impact a range of fields including cyber security and renewable energy.
Michael Manfra, the Bill and Dee O'Brian Professor of Physics and Astronomy, and professor in the School of Materials Engineering, and the School of Electrical and Computer Engineering, focuses on the creation and study of new materials with the potential to be used in quantum computers.
"Professor Manfra is one of our brightest research stars and is leading the charge to bring scientists and engineers together to solve some of humankind's most challenging technical problems", stated Jeffrey T. Roberts, the Frederick L. Hovde Dean of Purdue's College of Science. "He is an extraordinarily effective collaborator within and outside of Purdue, and I am so pleased at his role in making Purdue part of Microsoft's Station Q."
Classical computing carries information in binary code made up of ones and zeroes corresponding to on and off states of silicon transistors. Quantum computing is based on manipulation of information encoded in quantum state variables, for example the spin of an electron. The fundamental unit of information for quantum computing is the quantum bit or qubit.
How a practical quantum computer will ultimately be built is unknown. Possibilities include trapped ions, superconducting devices and isolated spins in semiconductor quantum dots. However, any potential qubit must overcome a large hurdle in order to be practical for quantum computing, Michael Manfra said.
"A big challenge in quantum computing is that qubits interact with their environment and are vulnerable to decoherence, or the loss of quantum information before a computation is complete or a result is stored in memory", he stated. "There are two approaches to this problem: accept it as a fact of life and try to correct for the errors decoherence introduces or, instead, be clever about the physical platform in which you make your qubit and try to use topology to make it insensitive to environmental noise. The latter is the idea behind topological quantum computing and is what Microsoft is pursuing."
Topological quantum computing protects qubits from noise because the quantum information is stored not in a single spin or ion, but rather in the interrelationship of correlated electrons. This type of qubit is less sensitive to the typical sources of noise found in solid-state systems, he said.
"An individual photon or phonon can easily disturb an individual spin or electron, but these and other noise sources do not couple strongly to the distributed nature of a topological qubit", Michael Manfra stated. "This is why topological qubits are expected to be more robust."
Michael Manfra and his collaborators use a technique called molecular beam epitaxy to create special, ultrapure materials to explore physics related to topological quantum computing. Through this technique single-atom-thin layers of different materials are grown in a perfectly aligned crystal lattice. Different combinations of materials and variations in the order of layers yield different electronic properties.
Gallium-arsenide material grown by the group has already been shown to have an electron mobility of 35 million centimeters squared per volt-second, which puts it among the highest levels of purity achieved by any group in the world.
With Microsoft support, Michael Manfra and his team will use molecular beam epitaxy to create new platforms for topological qubits.
For the Station Q at Purdue project Michael Manfra collaborated with research engineer and graduate student Geoff Gardner to design a new MBE system that will be housed in Purdue's Birck Nanotechnology Center in Discovery Park.
The new MBE system will grow hybrid semiconductor and superconductor structures in the hopes of finding valuable exotic electron phases at the intersection of the two different types of materials, Michael Manfra said.
To achieve the rare electronic states where topological qubits could reside, special combinations of materials must be created. One of the most promising potential routes to a topological qubit is based on combining certain semiconductors, like indium antimonide with superconducting materials like niobium, he said.
"This is new territory, and while it will be a challenge to create these hybrid materials, it is very exciting", he stated. "Theorists believe strong spin orbit coupling - which semiconductors produce - paired with a superconductor's ability to create correlations between electrons will lead to the phases we want. Our job is to create a material that has all of these properties and observe the desired properties."
Each of the materials are grown under different conditions that are sometimes at odds, and the new MBE will have a variety of components that will allow for flexibility in the growth process, he said. In addition the Michael Manfra group will develop new processes to enhance the compatibility of the different materials.
"Some of these materials can only be produced at high temperatures and others only at lower temperatures", Michael Manfra stated. "The trick will be to make each happy without undoing an earlier step. We've designed the new system to be adaptable so that as our understanding of the best way to create the materials evolves, the system can adjust. It is not equipment that can be disturbed or easily physically modified, so that ability has to be in the original design. I think our system is special, and we are eager to see what it can do."
Station Q's support and freedom given to study the fundamental physics that must be understood to achieve a topological quantum computer offers a rare opportunity, Michael Manfra said.
"The collaborative nature of the Station Q teams is like a virtual Bell Labs where groups with expertise in theory, measurement and materials come together as one team to explore the potential of new scientific territory", Michael Manfra stated. "One certainty is that along the way valuable insight into engineered quantum systems and coherent behavior will be gained. "