Reconstructing the quantum state of oscillator networks with a single qubit

TL;DR

This paper presents a resource-efficient method to reconstruct the quantum state of oscillator networks using a single qubit probe, enabling direct state measurement and property extraction without full tomography.

Contribution

The scheme requires only one qubit-oscillator interaction, tuning a single parameter, and provides direct state reconstruction, simplifying quantum state analysis of oscillator networks.

Findings

Reconstruction of arbitrary oscillator network states using minimal resources.

Direct extraction of quantum properties without full state tomography.

Feasibility of implementation with current trapped ion technology.

Abstract

We introduce a scheme to reconstruct arbitrary states of networks composed of quantum oscillators--e.g., the motional state of trapped ions or the radiation state of coupled cavities. The scheme uses minimal resources, in the sense that it i) requires only the interaction between one-qubit probe and one constituent of the network; ii) provides the reconstructed state directly from the data, avoiding any tomographic transformation; iii) involves the tuning of only one coupling parameter. In addition, we show that a number of quantum properties can be extracted without full reconstruction of the state. The scheme can be used for probing quantum simulations of anharmonic many-body systems and quantum computations with continuous variables. Experimental implementation with trapped ions is also discussed and shown to be within reach of current technology.