Bayesian tomography of high-dimensional on-chip biphoton frequency combs with randomized measurements

Area of Science:

• Quantum optics
• Quantum information science
• Integrated photonics

Background:

• Integrated biphoton frequency combs enable high-dimensional quantum information processing.
• Current quantum state tomography methods are complex and difficult to scale.

Purpose of the Study:

• To develop a scalable and simplified quantum state tomography technique for biphoton frequency combs.
• To verify entanglement and reconstruct the density matrix of high-dimensional biphoton states.

Main Methods:

• Utilized a pulse shaper and electro-optic phase modulator for random quantum operations.
• Employed a Bayesian statistical model for opportunistic quantum state tomography.
• Generated biphoton frequency combs using an on-chip silicon nitride microring resonator.

Main Results:

• Successfully verified entanglement in an 8x8-dimensional two-qudit Hilbert space.
• Reconstructed the full density matrix of biphoton frequency combs.
• Achieved the highest dimension to date for frequency bin entanglement.

Conclusions:

• The proposed method offers a scalable solution for quantum state tomography.
• The Bayesian statistical model is adaptable to various quantum systems with limited measurements.
• This work advances quantum information processing in the frequency domain.