Methods for Low-Overhead, Fault-Tolerant CNOT Operations.

Methods for Low-Overhead, Fault-Tolerant CNOT Operations between two Non-Nearest Neighboring Logical Qubits

Background:

The term Noisy Intermediate-Scale Quantum (NISQ) has been used to describe the current state of quantum computing technology because (1) qubits are highly error prone; and (2) the number of qubits in a single (monolithic) Quantum Processing Unit (QPU) are limited. In order to build a quantum computer useful for practical scientific and engineering applications, we need to improve the fault-tolerance performance and increase the number of qubits. This has led to an increased interest in quantum error correction (QEC) and distributed quantum computing (DQC).

Technology Overview:

This University at Buffalo technology addresses current limitations in quantum computing resulting from the high rate of error and limited qubit composition of current quantum computing syst0ems. Specifically, this method can act as a backbone for performing fault-tolerant logical operations in a Distributed Quantum computing (DQC) system using only one pair of entangled physical qubits during CNOT operation.

https://buffalo.technologypublisher.com/files/sites/7761_in-part_image.jpg

vchalup, https://stock.adobe.com/uk/234578887, stock.adobe.com

Advantages:

This method can be applied to any CSS code, which makes it more versatile than the specific variants.
The method has constant space overhead as it only requires one ancilla Bell Pair.
On top of requiring only one Bell pair established or routed, the proposed method will reduce the total number of physical CNOT operations on the physical qubits of A and B, respectively, from N down to possibly a very small number n < N

Application: