Quantum computing has the potential to utterly overturn what it means to compute. At Microsoft, we have been studying quantum computation since the late nineties with an eye towards a scalable universal quantum computer.
Quantum computers compute in a massively parallel fashion with computing power that scales exponentially with the size of the machine. Unlike classical bits, quantum bits, called ‘qubits’, can be in the value 0 and 1 at the same time. Quantum algorithms have been designed to take advantage of this scaling, and in turn can speed up database search and break certain cryptosystems like RSA.
Recently, corporate technology giants like Google and IBM have announced massive efforts towards building a scalable quantum computer—potentially a world-changing task. Their efforts are based on superconducting qubit designs. To achieve a reliable computation, additional resources are required to protect the qubits from becoming too noisy. This protection comes at a cost: large quantities of additional qubits are needed to produce one computational qubit. Running a non-trivial quantum algorithm demands upwards of 100 computational qubits, each of which require 100s to 1000s of additional qubits for protection in the superconducting qubit design.
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To circumvent the large qubit overhead, Microsoft is going in a different direction—focusing on a so-called topological qubit. The qubit design is based on Majorana quasiparticles, exotic physical phenomena successfully created and detected for the first time in 2012. Topological qubits can be formed from these Majorana quasiparticles and computed on by looping or ‘braiding’ Majoranas around each other. These braids are intrinsically stable by their very nature. Just as a braid or rope is robust to tugging and twisting, a topological qubit is extremely immune to perturbations and noise. This natural protection in turn reduces the need for additional qubits for protection, opening a door to a potentially more readily scalable design. The current challenge is to engineer the first topological qubit based on Majorana quasiparticles and to perform a small single-qubit quantum circuit by braiding.
The Microsoft Q Program (or simply ‘Q’) divides its main effort over two locations: Station Q in Santa Barbara focuses on theoretical physics and how we may realize a topological qubit, and the Quantum Architectures and Computation Group (QuArC), or ‘Station Q North’, focuses on computer science and software development, aiming to answer questions around what to do with a quantum computer and how to program it.
Part of Q revolves around experimental and theoretical research funded by Microsoft in universities around the globe. At the backbone of these satellite groups is Charlie Marcus, formerly of Harvard, now at the Niels Bohr Institute in Copenhagen, Denmark, Leo Kouwenhoven at TU Delft in the Netherlands, and David Reilly at the University of Sydney in Australia. Q’s leader and founder is Fields medallist Michael Freedman. Freedman oversees a remarkable cross-disciplinary collaboration between experimental researchers alongside Microsoft’s theoreticians, engineers, and quantum software developers. The collaborations aim to not only realize a topological qubit, but also to identify killer applications for quantum computers and to develop the software platform for programming and controlling them. Applications extend to areas as diverse as machine learning, drug design, and the development of new materials such as high-temperature superconductors.
Recommended Papers
Sankar Das Sarma, Michael Freedman, and Chetan Nayak
Topological quantum computation (opens in new tab)
Physics Today 7, 32 (2006)
Chetan Nayak, Steven H. Simon, Ady Stern, Michael Freedman, and Sankar Das Sarma
Non-Abelian anyons and topological quantum computation (opens in new tab)
Rev. Mod. Phys. 80, 1083 (2008)
Frank Wilczek
Majorana Returns (opens in new tab)
Nature Physics 5, 614 – 618 (2009)
Jason Alicea
New directions in the pursuit of Majorana fermions in solid state systems (opens in new tab)
Rep. Prog. Phys. 75, 076501 (2012)
(opens in new tab)Dr. Krysta Svore is a Senior Researcher at Microsoft Research in Redmond, Washington, where she manages the Quantum Architectures and Computation group. Svore’s research includes the development and implementation of quantum algorithms, including the design of a scalable, fault-tolerant software architecture for translating a high-level quantum program into a low-level, device-specific quantum implementation, and the study of quantum error correction codes and noise thresholds. She has also developed machine-learning methods for web applications, including ranking, classification, and summarization algorithms. Dr. Svore received an ACM Best of 2013 Notable Article award. In 2010, she was a member of the winning team of the Yahoo! Learning to Rank Challenge. She received her Ph.D. in Computer Science with highest distinction from Columbia University in 2006 and her B.A. from Princeton University in Mathematics and French in 2001. She is a Senior Member of the Association for Computing Machinery (ACM), serves as a representative for the Academic Alliance of the National Center for Women and Information Technology (NCWIT), and is an active member of the American Physical Society (APS).
For more information, visit http://research.microsoft.com/stationq (opens in new tab) and http://research.microsoft.com/quarc (opens in new tab)
Watch a 2014 interview with Krysta:
For more computer science research news, visit ResearchNews.com (opens in new tab).