Ghost imaging: from quantum to classical to computational

TLDR

Ghost imaging correlates a high‑resolution detector that sees a field not interacting with the object with a bucket detector that collects the field that has interacted, and has been demonstrated with thermal, biphoton, and classical Gaussian states that closely mimic biphoton behavior. This review presents a unified Gaussian‑state analysis of ghost imaging’s resolution, field of view, contrast, and signal‑to‑noise ratio, and introduces computational ghost imaging, a single‑beam variant requiring only a bucket detector. The analysis considers three illumination classes—thermal, biphoton, and classical phase‑sensitive light—and attributes performance to the coherence properties of Gaussian‑state beam pairs with phase‑insensitive or phase‑sensitive cross‑correlations. Quantitative results confirm the predicted behavior while highlighting the fundamental physics underlying ghost imaging.

Abstract

Ghost-imaging experiments correlate the outputs from two photodetectors: a high-spatial-resolution (scanning pinhole or CCD array) detector that measures a field that has not interacted with the object to be imaged, and a bucket (single-pixel) detector that collects a field that has interacted with the object. We give a comprehensive review of ghost imaging—within a unified Gaussian-state framework—presenting detailed analyses of its resolution, field of view, image contrast, and signal-to-noise ratio behavior. We consider three classes of illumination: thermal-state (classical), biphoton-state (quantum), and classical-state phase-sensitive light. The first two have been employed in a variety of ghost-imaging demonstrations. The third is the classical Gaussian state that produces ghost images that most closely mimic those obtained from biphoton illumination. The insights we develop lead naturally to a new, single-beam approach to ghost imaging, called computational ghost imaging, in which only the bucket detector is required. We provide quantitative results while simultaneously emphasizing the underlying physics of ghost imaging. The key to developing the latter understanding lies in the coherence behavior of a pair of Gaussian-state light beams with either phase-insensitive or phase-sensitive cross correlation.