Entanglement in systems of oscillators and quantum computations

TL;DR

This paper demonstrates that oscillator-based quantum devices, despite exhibiting entanglement, cannot achieve universal quantum computation, highlighting the limitations of such systems compared to other quantum platforms.

Contribution

It provides a theoretical analysis showing the limitations of oscillator-only quantum systems for universal computation and clarifies the role of entanglement in these systems.

Findings

Oscillator-based quantum devices cannot serve as universal quantum computers.

Entanglement exists in these devices but does not enable universality.

Ground state entanglement is primarily due to quasi-particles, unlike the electromagnetic vacuum.

Abstract

It is shown that quantum devices based only on oscillators cannot serve as the universal quantum computer, despite of entanglement in such devices, which we roughly estimate for the ideal case and for the harmful entanglement with photonic modes. We show that quasi-particles are the native shell for the entanglement already for ground state, in contast to the free electromagnetic field where vacuum state does not produce entanglement at all.