0.54 {\mu}m resolution two-photon interference with dispersion cancellation for quantum optical coherence tomography

TL;DR

This paper demonstrates a quantum optical coherence tomography technique achieving 0.54 μm resolution with dispersion cancellation, surpassing previous records and maintaining high resolution despite medium dispersion, advancing quantum metrology and biomedical imaging.

Contribution

The authors achieved record resolution in QOCT and demonstrated dispersion-insensitive imaging using a novel lithium tantalate device with nano-electrode-poling.

Findings

Achieved 0.54 μm resolution in two-photon interference.

Demonstrated dispersion cancellation over 1 mm water path.

Surpassed previous OCT resolution record of 0.75 μm.

Abstract

Quantum information technologies harness the intrinsic nature of quantum theory to beat the limitations of the classical methods for information processing and communication. Recently, the application of quantum features to metrology has attracted much attention. Quantum optical coherence tomography (QOCT), which utilizes two-photon interference between entangled photon pairs, is a promising approach to overcome the problem with optical coherence tomography (OCT): As the resolution of OCT becomes higher, degradation of the resolution due to dispersion within the medium becomes more critical. Here we report on the realization of 0.54 $\mu$m resolution two-photon interference, which surpasses the current record resolution 0.75 $\mu$m of low-coherence interference for OCT. In addition, the resolution for QOCT showed almost no change against the dispersion of a 1 mm thickness of water inserted in the optical path, whereas the resolution for OCT dramatically degrades. For this experiment, a highly-efficient chirped quasi-phase-matched lithium tantalate device was developed using a novel $`$nano-electrode-poling$'$ technique. The results presented here represent a breakthrough for the realization of quantum protocols, including QOCT, quantum clock synchronization, and more. Our work will open up possibilities for medical and biological applications.