Characterization of Arbitrary-Order Correlations in Quantum Baths by Weak Measurement

Area of Science:

• Quantum physics
• Quantum information science
• Condensed matter theory

Background:

• Quantum bath correlations drive system dynamics and thermodynamics.
• Characterizing high-order correlations in quantum baths is essential for quantum information technology but lacks systematic methods.
• Existing methods are limited to second-order or Gaussian approximations.

Purpose of the Study:

• To present a novel scheme for characterizing quantum bath correlations to arbitrary order.
• To enable a complete understanding of both classical and quantum correlations within quantum baths.
• To provide a foundation for optimizing quantum control and sensing in realistic quantum systems.

Main Methods:

• Utilizing weak measurements on the quantum bath.
• Employing projective measurements on a central system coupled to the bath.
• Reconstructing bath correlations from measurement output correlations.

Main Results:

• A systematic method to characterize many-body correlations in quantum baths to arbitrary order is established.
• Both classical and quantum components of bath correlations can be fully reconstructed.
• The scheme overcomes limitations of previous methods, such as the Gaussian approximation.

Conclusions:

• The developed scheme allows for the full characterization of many-body correlations in quantum baths.
• This capability is foundational for combating decoherence in quantum information processing.
• Applications include optimizing quantum control, studying bath quantum characteristics, and quantum sensing.