Universal Protection of Quantum States from Decoherence

TL;DR

This paper presents a universal, measurement-based protocol that protects arbitrary quantum states from decoherence by embedding them into a larger Hilbert space, validated experimentally on a quantum optical platform.

Contribution

It introduces a state- and dynamics-independent protection method that preserves quantum coherence without prior knowledge of the state.

Findings

Successfully preserves coherence and purity of arbitrary polarization qubits

Demonstrates robustness against environmental decoherence

Validates the protocol experimentally on a quantum optical system

Abstract

The fragility of quantum coherence fundamentally limits the scalability of quantum technologies, as unavoidable environmental interactions induce decoherence and rapidly degrade quantum properties. The Quantum Zeno Effect offers a powerful route to suppress quantum evolution and protect coherence through frequent measurements, irrespective of the underlying dynamics. However, existing implementations require prior knowledge of the quantum state, severely restricting their applicability. Here we introduce a state- and dynamics-independent protection protocol embedding the system in a larger Hilbert space, temporarily swapping the quantum information from its original degree of freedom to a decoherence-free ancillary one. We experimentally validate the protocol on a quantum optical platform, demonstrating robust preservation of coherence and purity for arbitrary polarization qubits under decoherence, thereby enabling the universal safeguarding of unknown quantum states.