Energetic Cost of Measurements Using Quantum, Coherent, and Thermal Light.

Area of Science:

• Quantum Information Science
• Quantum Optics
• Circuit Quantum Electrodynamics

Background:

• Quantum measurements are fundamental to quantum information processing and applications.
• The choice of light states (quantum, coherent, thermal) can influence measurement performance.
• Circuit quantum electrodynamics (cQED) provides a platform for studying quantum phenomena.

Purpose of the Study:

• To investigate the impact of different light states on quantum measurement performance in a cQED system.
• To compare measurement backaction and signal-to-noise ratio (SNR) per photon for various light states.
• To analyze the thermodynamic cost associated with each quantum measurement scheme.

Main Methods:

• Utilizing a circuit quantum electrodynamics setup.
• Comparing quantum, coherent, and classical thermal states of light.
• Analyzing measurement backaction and signal-to-noise ratio per photon.
• Evaluating the thermodynamic cost per information gain.

Main Results:

• In the strong dispersive limit, thermal light achieved quantum measurements with efficiency comparable to coherent light.
• Single-photon light demonstrated superior performance over both coherent and thermal light.
• Single-photon light exhibited the lowest energy cost per information gain, approaching the fundamental thermodynamic limit.

Conclusions:

• Single-photon light is the most efficient for quantum measurements in terms of performance and thermodynamic cost.
• Thermal light can be a viable alternative to coherent light for quantum measurements under specific conditions.
• Understanding these trade-offs is crucial for optimizing quantum information technologies.