Dynamic Generation of Topologically Protected Self-Correcting Quantum Memory

TL;DR

This paper presents a method to dynamically generate a topologically protected quantum memory using pulse sequences and cavity-mediated interactions, significantly enhancing memory lifetime.

Contribution

It introduces a scheme for creating a self-correcting quantum memory from common two-body interactions without measurements, using periodic pulses and cavity coupling.

Findings

Memory lifetime is significantly increased with cavity-mediated interactions.

Optimal pulse period T_opt maximizes fidelity.

Fidelity depends on pulse errors and period length.

Abstract

We propose a scheme to dynamically realize a quantum memory based on the toric code. The code is generated from qubit systems with typical two-body interactions (Ising, XY, Heisenberg) using periodic, NMR-like, pulse sequences. It allows one to encode the logical qubits without measurements and to protect them dynamically against the time evolution of the physical qubits. A weakly coupled cavity mode mediates a long-range attractive interaction between the stabilizer operators of the toric code, thereby suppressing the creation of thermal anyons. This significantly increases the lifetime of the memory compared to the code with noninteracting stabilizers. We investigate how the fidelity, with which the toric code is realized, depends on the period length T of the pulse sequence and the magnitude of possible pulse errors. We derive an optimal period T_opt that maximizes the fidelity.