Averaging gate approximation error and performance of Unitary Coupled Cluster ansatz in Pre-FTQC Era

Understand

Fault-tolerant quantum computation (FTQC) is essential to implement quantum algorithms in a noise-resilient way, and thus to enjoy advantages of quantum computers even with presence of noise.

• In FTQC, a quantum circuit is decomposed into universal gates that can be fault-tolerantly implemented, for example, Clifford+T gates.
• Here, T gate is usually regarded as an essential resource for quantum computation because its action cannot be simulated efficiently on classical computers and it is experimentally difficult to implement fault-tolerantly.
• Practically, it is highly likely that only a limited number of T gates are available in the near future.