Low overhead quantum computation using lattice surgery

When calculating the overhead of a quantum algorithm made fault-tolerant using the surface code, many previous works have used defects and braids for logical qubit storage and state distillation. In this work, we show that lattice surgery reduces the storage overhead by over a factor of 4, and the distillation overhead by nearly a factor of 5, making it possible to run algorithms with 10⁸ T gates using only 3. 7 10⁵ physical qubits capable of executing gates with error p 10^-3. These numbers strongly suggest that defects and braids in the surface code should be deprecated in favor of lattice surgery.