Any DOF all at once: single photon state tomography in a single measurement setup

Area of Science:

• Quantum Information Science
• Quantum Optics
• Photonic Quantum Technologies

Background:

• Photonic quantum technologies encode quantum information using light's degrees of freedom (DOFs).
• High-dimensional and hyperentangled states are crucial for enhancing quantum communication channel capacity and quantum operations.
• Efficiently measuring these states is challenging due to the extensive measurements required for quantum state tomography (QST).

Purpose of the Study:

• To propose a novel framework for reconstructing the density matrix of single-photon hyperentangled states.
• To simplify the measurement process for high-dimensional quantum states.
• To enable the use of traditional cameras for quantum state analysis.

Main Methods:

• Developed a framework utilizing a single intensity measurement from traditional cameras.
• Leveraged the spatial DOF of photons to encode information from other DOFs (e.g., OAM-spin, OAM-frequency).
• Numerically demonstrated the method using an ideal coupler and multimode fiber for information mixing and spatial encoding.

Main Results:

• Successfully reconstructed the density matrix of single-photon hyperentangled states.
• The proposed method simplifies experimental setups and reduces data acquisition time compared to traditional QST.
• Enabled recovery of DOFs (like polarization) not detectable by conventional cameras, eliminating the need for projection measurements.

Conclusions:

• The new technique offers a simplified and efficient approach to measuring high-dimensional quantum states.
• This advancement has the potential to accelerate the development of quantum communication and computation.
• The framework is extendable to multiphoton hyperentangled states, broadening its applicability.