Requirements for fault-tolerant quantum computation with cavity-QED-based atom-atom gates mediated by a photon with a finite pulse length

TL;DR

This paper investigates how to optimize cavity-QED parameters for atom-atom gates mediated by finite pulse length photons, aiming to minimize errors and relax fault-tolerance requirements in quantum computing.

Contribution

It introduces a new optimization method that balances shape distortion and photon loss, improving fault-tolerance in cavity-QED-based quantum gates.

Findings

Optimized system parameters reduce gate infidelity due to pulse distortion.

Reducing cavity length effectively decreases gate errors with short photon pulses.

The new optimization relaxes fault-tolerance requirements compared to previous methods.

Abstract

We analyze the requirements for fault-tolerant quantum computation with atom-atom gates based on cavity quantum electrodynamics (cQED) mediated by a photon with a finite pulse length. For short photon pulses, the distorted shape of the reflected pulses from the cQED system is a serious error source. We optimize the cQED system parameters to minimize the infidelity due to the shape distortion and the photon losses in a well-balanced manner for the fault-tolerant scheme using probabilistic gates [H. Goto and K. Ichimura, Phys. Rev. A 80, 040303(R) (2009)]. Our optimization greatly relaxes the requirements for fault-tolerant quantum computation in some parameter regions, compared with the conventional optimization method where only the photon loss is minimized without considering the shape distortion [H. Goto and K. Ichimura, Phys. Rev. A 82, 032311 (2010)]. Finally, we show that reducing the cavity length is an effective way to reduce the errors of this type of gate in the case of short photon pulses.