Low-overhead fault-tolerant quantum computing using long-range connectivity

20 Oct 2021  ·  Lawrence Z. Cohen, Isaac H. Kim, Stephen D. Bartlett, Benjamin J. Brown ·

Vast numbers of qubits will be needed for large-scale quantum computing using today's fault-tolerant architectures due to the overheads associated with quantum error correction. We present a scheme for low-overhead fault-tolerant quantum computation based on quantum low-density parity-check (LDPC) codes, where the capability of performing long-range entangling interactions allows a large number of logical qubits to be encoded with a modest number of physical qubits... In our approach, quantum logic gates operate via logical Pauli measurements that preserve both the protection of the LDPC codes as well as the low overheads in terms of required number of additional ancilla qubits. Compared with the surface code architecture, resource estimates for our scheme indicate order-of-magnitude improvements in the overheads for encoding and processing around one hundred logical qubits, meaning fault-tolerant quantum computation at this scale may be achievable with a few thousand physical qubits at achievable error rates. read more

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Quantum Physics