Work

Full Schmidt characterization of spatiotemporally entangled states produced from spontaneous parametric down-conversion

Year: 2026

Type: article

Abstract: The full Schmidt decomposition of spatiotemporally entangled states generated from spontaneous parametric down-conversion (SPDC) has not been carried out until now due to the immense computational complexity arising from the large dimensionalities of the states. In this Letter, we utilize the rotational symmetry of the states to reduce the complexity by at least four orders of magnitude and carry out the decomposition to reveal the precise forms of the spatiotemporal Schmidt modes and the Schmidt spectrum spanning over 10^4 modes. We show that the Schmidt modes have a phase profile with a transverse spatial vortex structure that endows them with orbital angular momentum at all frequencies. In the high-gain regime, these Schmidt modes broaden and the Schmidt spectrum narrows with increasing pump strength. Our work can spur novel applications at the intersection of quantum imaging and spectroscopy that utilize entangled states produced from SPDC.

Source: Physical Review A

DOI: 10.1103/rfgp-kfhb

Authors: Rakesh Pradhan, Girish Kulkarni

Institution: Indian Institute of Technology Ropar

Language: English

Topic: Quantum Information and Cryptography

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: Department of Science and Technology, Ministry of Science and Technology, India, Indian Institute of Technology Ropar

OpenAlex ID: W7167622406

FWCI:

Cites: 68

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Related to: 10