Multichannel optimal squeezing-displacement feedforward receiver with realistic photon-number-resolving detectors

Area of Science:

• Quantum optics
• Quantum communication

Background:

• Binary phase-shift keying (BPSK) is a fundamental digital modulation scheme.
• Squeezing-based receivers offer advantages but are often limited to low photon numbers.
• Photon-number-resolving detectors are crucial for advanced quantum measurements.

Purpose of the Study:

• To propose and analyze a multichannel optimal squeezing-displacement receiver (MOSDR).
• To improve the performance of BPSK coherent state discrimination beyond the standard quantum limit.
• To enhance the effectiveness of squeezing operations in practical photon number regimes.

Main Methods:

• Partitioning the input signal into multiple channels to reduce mean photon number per channel.
• Employing displacement feedforward between channels.
• Accumulating per-channel discrimination outcomes via a sequential decision process.
• Analyzing receiver performance under ideal and non-ideal detector conditions (quantum efficiency, dark counts, visibility reduction).

Main Results:

• MOSDR outperforms optimized-displacement multichannel displacement feedforward receivers.
• The receiver consistently operates below the standard quantum limit across a broad photon-number range.
• MOSDR demonstrates improved robustness against detection imperfections.

Conclusions:

• The proposed MOSDR effectively enhances BPSK coherent state discrimination.
• Multichannel partitioning and sequential decision-making are key to improving squeezing-based receiver performance.
• MOSDR represents a significant advancement in quantum receiver technology, offering superior performance and robustness.