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This paper discusses the techniques of mapping and scheduling multi-level distillation circuits for fault-tolerant quantum architectures, focusing on magic-state distillation and braiding operations. It presents concatenation and force-directed annealing techniques and provides results on fault-tolerant operations and the cost of permutation steps. The paper also explores communication via braiding and techniques for congestion minimization. The force-directed annealing method is evaluated, and the results show a reduction in circuit latency and edge crossings. The paper concludes with the optimization of multi-level circuits using hierarchical stitching.
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Magic-State Functional Units Mapping and Scheduling Multi-Level Distillation Circuits for Fault-Tolerant Quantum Architectures OCT 24, 2018 Ding, Y., Holmes, A., Javadi-Abhari, A., Franklin, D., Martonosi, M., & Chong, F. T. ArXiv: 1809.01302 DOI: 10.1109/MICRO.2018.00072
OUTLINE 1 Background Magic-State Distillation and Braiding Our Techniques 2 Concatenation and Force-directed Annealing 3 Results
FAULT-TOLERANT QC Operations on Error-Corrected Quantum Computers Difficult 2-qubit gate: CNOT gate Easy single-qubit gates: H X Z Expensive to implement: requires braiding Difficult single-qubit gate: T gate T | Useful applications contain a significant number of T gates. Consume: 1 magic state Expensive to implement: requires magic state distillation
MAGIC-STATE DISTILLATION Magic State Distillation is Expensive Quantum Chemistry *Ising Model of spin chain with size 500. Ising Model QFT Operations spent on magic state distillation: 99.4% Operations spent on distillation (percentage) Common Kernel *Quantum Fourier Transform with size 100. Operations spent on magic state distillation: 99.8% T-gate Percentage
MAGIC-STATE DISTILLATION Block Code Distillation Factory T T p2 T p T T “Distillation Factory” T
COMMUNICATION VIA BRAIDING A Distance does not matter.
COMMUNICATION VIA BRAIDING B A C Crossing is prohibited.
COMMUNICATION VIA BRAIDING Fewer crossings?
OBJECTIVE Mapping
TECHNIQUES Mapping
TECHNIQUES Concatenate and Arrange Cost of Permutation Step 78% 66% 48% 48% 28% 4 16 36 64 100
TECHNIQUES Force-Directed Annealing 1 Vertex-Vertex Attraction 2 Edge-Edge Repulsion 3 Magnetic Dipole Source: http://jsfiddle.net/4sq4F/
FORCE-DIRECTED ANNEALING Vertex-Vertex Attraction Calculated with cycle-by-cycle simulation
FORCE-DIRECTED ANNEALING Edge-Edge Repulsion
Magnetic Dipole + + - - - + -
FORCE-DIRECTED ANNEALING Magnetic Dipole Rotation
FORCE-DIRECTED ANNEALING Valiant-Style Routing Intermediate hops
RESULTS Multi-Level Factories 5.6x overhead reduction
Conclusion • Magic-state distillation extremely dominates most applications’ workloads. • Surface code braiding circuits are difficult to execute. • Circuit latency and edge crossings are strongly correlated. • Force-directed annealing heuristics generate low-latency qubit mappings. • Hierarchical stitching optimizes multi-level circuits
Thank you! Magic-State Functional Units: Mapping and Scheduling Multi-Level Distillation Circuits for Fault-Tolerant Quantum Architectures. Ding, Y., Holmes, A., Javadi-Abhari, A., Franklin, D., Martonosi, M., & Chong, F. T. (2018). arXiv preprint arXiv:1809.01302.