On the Use of Shor States for the [7,1,3] Quantum Error Correcting Code

TL;DR

This paper investigates how different methods of constructing Shor states affect the performance of the [[7,1,3]] quantum error correction code, highlighting optimal verification steps and comparing to non-Shor state approaches.

Contribution

It identifies optimal verification procedures for Shor states and compares their effectiveness to non-Shor state methods in quantum error correction.

Findings

Shor state verification steps can be optimized for better performance.

Error correction with a single syndrome qubit performs comparably to Shor states.

Shor states exhibit sensitivity to bit-flip errors, affecting correction accuracy.

Abstract

We explore the effect of Shor state construction methods on logical state encoding and quantum error correction for the [[7,1,3]] Calderbank-Shor-Steane quantum error correction code in a nonequiprobable error environment. We determine the optimum number of verification steps to be used in Shor state construction and whether Shor states without verification are usable for practical quantum computation. These results are compared to the same processes of encoding and error correction where Shor states are not used. We demonstrate that the construction of logical zero states with no first order error terms may not require the complete edifice of quantum fault tolerance. With respect to error correction, we show for a particular initial state that error correction using a single qubit for syndrome measurement yields a similar output state accuracy to error correction using Shor states as syndrome qubits. In addition, we demonstrate that error correction with Shor states has an inherent sensitivity to bit-flip errors. Finally, we suggest that in this type of error correction scenario one should always repeat a syndrome measurement until attaining an all zero readout (twice in row).