Quantum-enhanced phase estimation with photon-engineered multi-headed cat states

Area of Science:

• Quantum optics
• Quantum information science
• Quantum metrology

Background:

• Multi-headed Schrödinger cat states (MHCS) are crucial for advanced quantum technologies.
• Engineering these states via multiphoton processes is key to enhancing quantum sensing capabilities.

Purpose of the Study:

• To investigate the impact of multiphoton addition and subtraction sequences on MHCS.
• To determine the optimal sequence for maximizing phase sensitivity in quantum metrology.
• To analyze the performance of different MHCS, including three-headed (3HCS) and four-headed (4HCS) states.

Main Methods:

• Engineered MHCS using sequences of multiphoton addition and subtraction.
• Analyzed phase sensitivity across different sequences (addition, subtraction, addition-then-subtraction, subtraction-then-addition).
• Evaluated performance of even, odd, 3HCS, and 4HCS, considering Wigner negativity and operator noncommutativity.

Main Results:

• The addition-then-subtraction sequence consistently provided the highest phase sensitivity.
• Operator noncommutativity was identified as a critical factor in quantum metrology.
• Four-headed cat states (4HCS) demonstrated the best performance due to enhanced interference, surpassing the shot-noise limit.
• Investigated robustness against photon loss and dephasing, confirming practical advantages.

Conclusions:

• The addition-then-subtraction sequence is optimal for quantum metrology with MHCS.
• 4HCS exhibit superior performance for quantum sensing applications.
• MHCS engineered through specific multiphoton sequences offer practical advantages for quantum sensing.