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IQIM Postdoctoral and Graduate Student Seminar

Wednesday, February 2, 2022
11:00am to 12:00pm
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Online Event
A circuit-level protocol and analysis for twist-based lattice surgery
Christopher Chamberland, AWS Center for Quantum Computing,

Joint IQIM/AWS Seminar

Abstract: Lattice surgery is a measurement-based technique for performing fault-tolerant quantum computation in two dimensions. When using the surface code, the most general lattice surgery operations require lattice irregularities called twist defects. However, implementing twist-based lattice surgery may require additional resources, such as extra device connectivity, and could lower the threshold and overall performance for the surface code. In this talk I will provide an explicit twist-based lattice surgery protocol and its requisite connectivity layout. I will also describe new stabilizer measurement circuits for measuring twist defects which are compatible with our chosen gate scheduling. After performing a full circuit-level noise analysis. our results indicate a slight decrease in the threshold for timelike logical failures compared to lattice surgery protocols with no twist defects in the bulk. However, comfortably below threshold (i.e. with CNOT infidelities below 5 × 10−3 ), the performance degradation is mild and in fact preferable over proposed alternative twist-free schemes. Lastly, I will discuss an efficient scheme for measuring Y operators along boundaries of surface codes which bypasses certain steps that were required in previous schemes and significantly reduces algorithm runtimes when using twist defects.

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For more information, please contact Marcia Brown by phone at 626-395-4013 or by email at [email protected].